reorganise repo structure

8 files changed, 1581 insertions, 0 deletions

diff --git a/src/SMAPI.Tests/Core/ModResolverTests.cs b/src/SMAPI.Tests/Core/ModResolverTests.cs
new file mode 100644
index 00000000..051ffe99
--- /dev/null
+++ b/src/SMAPI.Tests/Core/ModResolverTests.cs
@@ -0,0 +1,556 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Moq;
+using Newtonsoft.Json;
+using NUnit.Framework;
+using StardewModdingAPI.Framework;
+using StardewModdingAPI.Framework.Models;
+using StardewModdingAPI.Framework.ModLoading;
+using StardewModdingAPI.Framework.Serialisation;
+
+namespace StardewModdingAPI.Tests.Core
+{
+    /// <summary>Unit tests for <see cref="ModResolver"/>.</summary>
+    [TestFixture]
+    public class ModResolverTests
+    {
+        /*********
+        ** Unit tests
+        *********/
+        /****
+        ** ReadManifests
+        ****/
+        [Test(Description = "Assert that the resolver correctly returns an empty list if there are no mods installed.")]
+        public void ReadBasicManifest_NoMods_ReturnsEmptyList()
+        {
+            // arrange
+            string rootFolder = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
+            Directory.CreateDirectory(rootFolder);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ReadManifests(rootFolder, new JsonHelper(), new ModDataRecord[0]).ToArray();
+
+            // assert
+            Assert.AreEqual(0, mods.Length, 0, $"Expected to find zero manifests, found {mods.Length} instead.");
+        }
+
+        [Test(Description = "Assert that the resolver correctly returns a failed metadata if there's an empty mod folder.")]
+        public void ReadBasicManifest_EmptyModFolder_ReturnsFailedManifest()
+        {
+            // arrange
+            string rootFolder = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
+            string modFolder = Path.Combine(rootFolder, Guid.NewGuid().ToString("N"));
+            Directory.CreateDirectory(modFolder);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ReadManifests(rootFolder, new JsonHelper(), new ModDataRecord[0]).ToArray();
+            IModMetadata mod = mods.FirstOrDefault();
+
+            // assert
+            Assert.AreEqual(1, mods.Length, 0, $"Expected to find one manifest, found {mods.Length} instead.");
+            Assert.AreEqual(ModMetadataStatus.Failed, mod.Status, "The mod metadata was not marked failed.");
+            Assert.IsNotNull(mod.Error, "The mod metadata did not have an error message set.");
+        }
+
+        [Test(Description = "Assert that the resolver correctly reads manifest data from a randomised file.")]
+        public void ReadBasicManifest_CanReadFile()
+        {
+            // create manifest data
+            IDictionary<string, object> originalDependency = new Dictionary<string, object>
+            {
+                [nameof(IManifestDependency.UniqueID)] = Sample.String()
+            };
+            IDictionary<string, object> original = new Dictionary<string, object>
+            {
+                [nameof(IManifest.Name)] = Sample.String(),
+                [nameof(IManifest.Author)] = Sample.String(),
+                [nameof(IManifest.Version)] = new SemanticVersion(Sample.Int(), Sample.Int(), Sample.Int(), Sample.String()),
+                [nameof(IManifest.Description)] = Sample.String(),
+                [nameof(IManifest.UniqueID)] = $"{Sample.String()}.{Sample.String()}",
+                [nameof(IManifest.EntryDll)] = $"{Sample.String()}.dll",
+                [nameof(IManifest.MinimumApiVersion)] = $"{Sample.Int()}.{Sample.Int()}-{Sample.String()}",
+                [nameof(IManifest.Dependencies)] = new[] { originalDependency },
+                ["ExtraString"] = Sample.String(),
+                ["ExtraInt"] = Sample.Int()
+            };
+
+            // write to filesystem
+            string rootFolder = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
+            string modFolder = Path.Combine(rootFolder, Guid.NewGuid().ToString("N"));
+            string filename = Path.Combine(modFolder, "manifest.json");
+            Directory.CreateDirectory(modFolder);
+            File.WriteAllText(filename, JsonConvert.SerializeObject(original));
+
+            // act
+            IModMetadata[] mods = new ModResolver().ReadManifests(rootFolder, new JsonHelper(), new ModDataRecord[0]).ToArray();
+            IModMetadata mod = mods.FirstOrDefault();
+
+            // assert
+            Assert.AreEqual(1, mods.Length, 0, "Expected to find one manifest.");
+            Assert.IsNotNull(mod, "The loaded manifest shouldn't be null.");
+            Assert.AreEqual(null, mod.DataRecord, "The data record should be null since we didn't provide one.");
+            Assert.AreEqual(modFolder, mod.DirectoryPath, "The directory path doesn't match.");
+            Assert.AreEqual(ModMetadataStatus.Found, mod.Status, "The status doesn't match.");
+            Assert.AreEqual(null, mod.Error, "The error should be null since parsing should have succeeded.");
+
+            Assert.AreEqual(original[nameof(IManifest.Name)], mod.DisplayName, "The display name should use the manifest name.");
+            Assert.AreEqual(original[nameof(IManifest.Name)], mod.Manifest.Name, "The manifest's name doesn't match.");
+            Assert.AreEqual(original[nameof(IManifest.Author)], mod.Manifest.Author, "The manifest's author doesn't match.");
+            Assert.AreEqual(original[nameof(IManifest.Description)], mod.Manifest.Description, "The manifest's description doesn't match.");
+            Assert.AreEqual(original[nameof(IManifest.EntryDll)], mod.Manifest.EntryDll, "The manifest's entry DLL doesn't match.");
+            Assert.AreEqual(original[nameof(IManifest.MinimumApiVersion)], mod.Manifest.MinimumApiVersion?.ToString(), "The manifest's minimum API version doesn't match.");
+            Assert.AreEqual(original[nameof(IManifest.Version)]?.ToString(), mod.Manifest.Version?.ToString(), "The manifest's version doesn't match.");
+
+            Assert.IsNotNull(mod.Manifest.ExtraFields, "The extra fields should not be null.");
+            Assert.AreEqual(2, mod.Manifest.ExtraFields.Count, "The extra fields should contain two values.");
+            Assert.AreEqual(original["ExtraString"], mod.Manifest.ExtraFields["ExtraString"], "The manifest's extra fields should contain an 'ExtraString' value.");
+            Assert.AreEqual(original["ExtraInt"], mod.Manifest.ExtraFields["ExtraInt"], "The manifest's extra fields should contain an 'ExtraInt' value.");
+
+            Assert.IsNotNull(mod.Manifest.Dependencies, "The dependencies field should not be null.");
+            Assert.AreEqual(1, mod.Manifest.Dependencies.Length, "The dependencies field should contain one value.");
+            Assert.AreEqual(originalDependency[nameof(IManifestDependency.UniqueID)], mod.Manifest.Dependencies[0].UniqueID, "The first dependency's unique ID doesn't match.");
+        }
+
+        /****
+        ** ValidateManifests
+        ****/
+        [Test(Description = "Assert that validation doesn't fail if there are no mods installed.")]
+        public void ValidateManifests_NoMods_DoesNothing()
+        {
+            new ModResolver().ValidateManifests(new ModMetadata[0], apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+        }
+
+        [Test(Description = "Assert that validation skips manifests that have already failed without calling any other properties.")]
+        public void ValidateManifests_Skips_Failed()
+        {
+            // arrange
+            Mock<IModMetadata> mock = this.GetMetadata("Mod A");
+            mock.Setup(p => p.Status).Returns(ModMetadataStatus.Failed);
+
+            // act
+            new ModResolver().ValidateManifests(new[] { mock.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            mock.VerifyGet(p => p.Status, Times.Once, "The validation did not check the manifest status.");
+        }
+
+        [Test(Description = "Assert that validation fails if the mod has 'assume broken' status.")]
+        public void ValidateManifests_ModStatus_AssumeBroken_Fails()
+        {
+            // arrange
+            Mock<IModMetadata> mock = this.GetMetadata("Mod A", new string[0], allowStatusChange: true);
+            this.SetupMetadataForValidation(mock, new ModDataRecord
+            {
+                Compatibility = new[] { new ModCompatibility("~1.0", ModStatus.AssumeBroken, null) },
+                AlternativeUrl = "http://example.org"
+            });
+
+            // act
+            new ModResolver().ValidateManifests(new[] { mock.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            mock.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "The validation did not fail the metadata.");
+        }
+
+        [Test(Description = "Assert that validation fails when the minimum API version is higher than the current SMAPI version.")]
+        public void ValidateManifests_MinimumApiVersion_Fails()
+        {
+            // arrange
+            Mock<IModMetadata> mock = this.GetMetadata("Mod A", new string[0], allowStatusChange: true);
+            mock.Setup(p => p.Manifest).Returns(this.GetManifest(m => m.MinimumApiVersion = new SemanticVersion("1.1")));
+            this.SetupMetadataForValidation(mock);
+
+            // act
+            new ModResolver().ValidateManifests(new[] { mock.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            mock.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "The validation did not fail the metadata.");
+        }
+
+        [Test(Description = "Assert that validation fails when the manifest references a DLL that does not exist.")]
+        public void ValidateManifests_MissingEntryDLL_Fails()
+        {
+            // arrange
+            Mock<IModMetadata> mock = this.GetMetadata(this.GetManifest("Mod A", "1.0", manifest => manifest.EntryDll = "Missing.dll"), allowStatusChange: true);
+            this.SetupMetadataForValidation(mock);
+
+            // act
+            new ModResolver().ValidateManifests(new[] { mock.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            mock.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "The validation did not fail the metadata.");
+        }
+
+        [Test(Description = "Assert that validation fails when multiple mods have the same unique ID.")]
+        public void ValidateManifests_DuplicateUniqueID_Fails()
+        {
+            // arrange
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A", new string[0], allowStatusChange: true);
+            Mock<IModMetadata> modB = this.GetMetadata(this.GetManifest("Mod A", "1.0", manifest => manifest.Name = "Mod B"), allowStatusChange: true);
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", new string[0], allowStatusChange: false);
+            foreach (Mock<IModMetadata> mod in new[] { modA, modB, modC })
+                this.SetupMetadataForValidation(mod);
+
+            // act
+            new ModResolver().ValidateManifests(new[] { modA.Object, modB.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            modA.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "The validation did not fail the first mod with a unique ID.");
+            modB.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "The validation did not fail the second mod with a unique ID.");
+        }
+
+        [Test(Description = "Assert that validation fails when the manifest references a DLL that does not exist.")]
+        public void ValidateManifests_Valid_Passes()
+        {
+            // set up manifest
+            IManifest manifest = this.GetManifest();
+
+            // create DLL
+            string modFolder = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
+            Directory.CreateDirectory(modFolder);
+            File.WriteAllText(Path.Combine(modFolder, manifest.EntryDll), "");
+
+            // arrange
+            Mock<IModMetadata> mock = new Mock<IModMetadata>(MockBehavior.Strict);
+            mock.Setup(p => p.Status).Returns(ModMetadataStatus.Found);
+            mock.Setup(p => p.DataRecord).Returns(() => null);
+            mock.Setup(p => p.Manifest).Returns(manifest);
+            mock.Setup(p => p.DirectoryPath).Returns(modFolder);
+
+            // act
+            new ModResolver().ValidateManifests(new[] { mock.Object }, apiVersion: new SemanticVersion("1.0"), vendorModUrls: new Dictionary<string, string>());
+
+            // assert
+            // if Moq doesn't throw a method-not-setup exception, the validation didn't override the status.
+        }
+
+        /****
+        ** ProcessDependencies
+        ****/
+        [Test(Description = "Assert that processing dependencies doesn't fail if there are no mods installed.")]
+        public void ProcessDependencies_NoMods_DoesNothing()
+        {
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new IModMetadata[0]).ToArray();
+
+            // assert
+            Assert.AreEqual(0, mods.Length, 0, "Expected to get an empty list of mods.");
+        }
+
+        [Test(Description = "Assert that processing dependencies doesn't change the order if there are no mod dependencies.")]
+        public void ProcessDependencies_NoDependencies_DoesNothing()
+        {
+            // arrange
+            // A B C
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B");
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C");
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modA.Object, modB.Object, modC.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(3, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order unexpectedly changed with no dependencies.");
+            Assert.AreSame(modB.Object, mods[1], "The load order unexpectedly changed with no dependencies.");
+            Assert.AreSame(modC.Object, mods[2], "The load order unexpectedly changed with no dependencies.");
+        }
+
+        [Test(Description = "Assert that processing dependencies skips mods that have already failed without calling any other properties.")]
+        public void ProcessDependencies_Skips_Failed()
+        {
+            // arrange
+            Mock<IModMetadata> mock = new Mock<IModMetadata>(MockBehavior.Strict);
+            mock.Setup(p => p.Status).Returns(ModMetadataStatus.Failed);
+
+            // act
+            new ModResolver().ProcessDependencies(new[] { mock.Object });
+
+            // assert
+            mock.VerifyGet(p => p.Status, Times.Once, "The validation did not check the manifest status.");
+        }
+
+        [Test(Description = "Assert that simple dependencies are reordered correctly.")]
+        public void ProcessDependencies_Reorders_SimpleDependencies()
+        {
+            // arrange
+            // A ◀── B
+            // ▲     ▲
+            // │     │
+            // └─ C ─┘
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B", dependencies: new[] { "Mod A" });
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", dependencies: new[] { "Mod A", "Mod B" });
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modC.Object, modA.Object, modB.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(3, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since the other mods depend on it.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A, and is needed by mod C.");
+            Assert.AreSame(modC.Object, mods[2], "The load order is incorrect: mod C should be third since it needs both mod A and mod B.");
+        }
+
+        [Test(Description = "Assert that simple dependency chains are reordered correctly.")]
+        public void ProcessDependencies_Reorders_DependencyChain()
+        {
+            // arrange
+            // A ◀── B ◀── C ◀── D
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B", dependencies: new[] { "Mod A" });
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", dependencies: new[] { "Mod B" });
+            Mock<IModMetadata> modD = this.GetMetadata("Mod D", dependencies: new[] { "Mod C" });
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modC.Object, modA.Object, modB.Object, modD.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(4, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A, and is needed by mod C.");
+            Assert.AreSame(modC.Object, mods[2], "The load order is incorrect: mod C should be third since it needs mod B, and is needed by mod D.");
+            Assert.AreSame(modD.Object, mods[3], "The load order is incorrect: mod D should be fourth since it needs mod C.");
+        }
+
+        [Test(Description = "Assert that overlapping dependency chains are reordered correctly.")]
+        public void ProcessDependencies_Reorders_OverlappingDependencyChain()
+        {
+            // arrange
+            // A ◀── B ◀── C ◀── D
+            //       ▲     ▲
+            //       │     │
+            //       E ◀── F
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B", dependencies: new[] { "Mod A" });
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", dependencies: new[] { "Mod B" });
+            Mock<IModMetadata> modD = this.GetMetadata("Mod D", dependencies: new[] { "Mod C" });
+            Mock<IModMetadata> modE = this.GetMetadata("Mod E", dependencies: new[] { "Mod B" });
+            Mock<IModMetadata> modF = this.GetMetadata("Mod F", dependencies: new[] { "Mod C", "Mod E" });
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modC.Object, modA.Object, modB.Object, modD.Object, modF.Object, modE.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(6, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A, and is needed by mod C.");
+            Assert.AreSame(modC.Object, mods[2], "The load order is incorrect: mod C should be third since it needs mod B, and is needed by mod D.");
+            Assert.AreSame(modD.Object, mods[3], "The load order is incorrect: mod D should be fourth since it needs mod C.");
+            Assert.AreSame(modE.Object, mods[4], "The load order is incorrect: mod E should be fifth since it needs mod B, but is specified after C which also needs mod B.");
+            Assert.AreSame(modF.Object, mods[5], "The load order is incorrect: mod F should be last since it needs mods E and C.");
+        }
+
+        [Test(Description = "Assert that mods with circular dependency chains are skipped, but any other mods are loaded in the correct order.")]
+        public void ProcessDependencies_Skips_CircularDependentMods()
+        {
+            // arrange
+            // A ◀── B ◀── C ──▶ D
+            //             ▲     │
+            //             │     ▼
+            //             └──── E
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B", dependencies: new[] { "Mod A" });
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", dependencies: new[] { "Mod B", "Mod D" }, allowStatusChange: true);
+            Mock<IModMetadata> modD = this.GetMetadata("Mod D", dependencies: new[] { "Mod E" }, allowStatusChange: true);
+            Mock<IModMetadata> modE = this.GetMetadata("Mod E", dependencies: new[] { "Mod C" }, allowStatusChange: true);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modC.Object, modA.Object, modB.Object, modD.Object, modE.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(5, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A.");
+            modC.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "Mod C was expected to fail since it's part of a dependency loop.");
+            modD.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "Mod D was expected to fail since it's part of a dependency loop.");
+            modE.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "Mod E was expected to fail since it's part of a dependency loop.");
+        }
+
+        [Test(Description = "Assert that dependencies are sorted correctly even if some of the mods failed during metadata loading.")]
+        public void ProcessDependencies_WithSomeFailedMods_Succeeds()
+        {
+            // arrange
+            // A ◀── B ◀── C   D (failed)
+            Mock<IModMetadata> modA = this.GetMetadata("Mod A");
+            Mock<IModMetadata> modB = this.GetMetadata("Mod B", dependencies: new[] { "Mod A" });
+            Mock<IModMetadata> modC = this.GetMetadata("Mod C", dependencies: new[] { "Mod B" }, allowStatusChange: true);
+            Mock<IModMetadata> modD = new Mock<IModMetadata>(MockBehavior.Strict);
+            modD.Setup(p => p.Manifest).Returns<IManifest>(null);
+            modD.Setup(p => p.Status).Returns(ModMetadataStatus.Failed);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modC.Object, modA.Object, modB.Object, modD.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(4, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modD.Object, mods[0], "The load order is incorrect: mod D should be first since it was already failed.");
+            Assert.AreSame(modA.Object, mods[1], "The load order is incorrect: mod A should be second since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[2], "The load order is incorrect: mod B should be third since it needs mod A, and is needed by mod C.");
+            Assert.AreSame(modC.Object, mods[3], "The load order is incorrect: mod C should be fourth since it needs mod B, and is needed by mod D.");
+        }
+
+        [Test(Description = "Assert that dependencies are failed if they don't meet the minimum version.")]
+        public void ProcessDependencies_WithMinVersions_FailsIfNotMet()
+        {
+            // arrange
+            // A 1.0 ◀── B (need A 1.1)
+            Mock<IModMetadata> modA = this.GetMetadata(this.GetManifest("Mod A", "1.0"));
+            Mock<IModMetadata> modB = this.GetMetadata(this.GetManifest("Mod B", "1.0", new ManifestDependency("Mod A", "1.1")), allowStatusChange: true);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modA.Object, modB.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(2, mods.Length, 0, "Expected to get the same number of mods input.");
+            modB.Verify(p => p.SetStatus(ModMetadataStatus.Failed, It.IsAny<string>()), Times.Once, "Mod B unexpectedly didn't fail even though it needs a newer version of Mod A.");
+        }
+
+        [Test(Description = "Assert that dependencies are accepted if they meet the minimum version.")]
+        public void ProcessDependencies_WithMinVersions_SucceedsIfMet()
+        {
+            // arrange
+            // A 1.0 ◀── B (need A 1.0-beta)
+            Mock<IModMetadata> modA = this.GetMetadata(this.GetManifest("Mod A", "1.0"));
+            Mock<IModMetadata> modB = this.GetMetadata(this.GetManifest("Mod B", "1.0", new ManifestDependency("Mod A", "1.0-beta")), allowStatusChange: false);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modA.Object, modB.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(2, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A.");
+        }
+
+        [Test(Description = "Assert that optional dependencies are sorted correctly if present.")]
+        public void ProcessDependencies_IfOptional()
+        {
+            // arrange
+            // A ◀── B
+            Mock<IModMetadata> modA = this.GetMetadata(this.GetManifest("Mod A", "1.0"));
+            Mock<IModMetadata> modB = this.GetMetadata(this.GetManifest("Mod B", "1.0", new ManifestDependency("Mod A", "1.0", required: false)), allowStatusChange: false);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modB.Object, modA.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(2, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modA.Object, mods[0], "The load order is incorrect: mod A should be first since it's needed by mod B.");
+            Assert.AreSame(modB.Object, mods[1], "The load order is incorrect: mod B should be second since it needs mod A.");
+        }
+
+        [Test(Description = "Assert that optional dependencies are accepted if they're missing.")]
+        public void ProcessDependencies_IfOptional_SucceedsIfMissing()
+        {
+            // arrange
+            // A ◀── B where A doesn't exist
+            Mock<IModMetadata> modB = this.GetMetadata(this.GetManifest("Mod B", "1.0", new ManifestDependency("Mod A", "1.0", required: false)), allowStatusChange: false);
+
+            // act
+            IModMetadata[] mods = new ModResolver().ProcessDependencies(new[] { modB.Object }).ToArray();
+
+            // assert
+            Assert.AreEqual(1, mods.Length, 0, "Expected to get the same number of mods input.");
+            Assert.AreSame(modB.Object, mods[0], "The load order is incorrect: mod B should be first since it's the only mod.");
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="adjust">Adjust the generated manifest.</param>
+        private Manifest GetManifest(Action<Manifest> adjust = null)
+        {
+            Manifest manifest = new Manifest
+            {
+                Name = Sample.String(),
+                Author = Sample.String(),
+                Version = new SemanticVersion(Sample.Int(), Sample.Int(), Sample.Int(), Sample.String()),
+                Description = Sample.String(),
+                UniqueID = $"{Sample.String()}.{Sample.String()}",
+                EntryDll = $"{Sample.String()}.dll"
+            };
+            adjust?.Invoke(manifest);
+            return manifest;
+        }
+
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="uniqueID">The mod's name and unique ID.</param>
+        /// <param name="version">The mod version.</param>
+        /// <param name="adjust">Adjust the generated manifest.</param>
+        /// <param name="dependencies">The dependencies this mod requires.</param>
+        private IManifest GetManifest(string uniqueID, string version, Action<Manifest> adjust, params IManifestDependency[] dependencies)
+        {
+            return this.GetManifest(manifest =>
+            {
+                manifest.Name = uniqueID;
+                manifest.UniqueID = uniqueID;
+                manifest.Version = new SemanticVersion(version);
+                manifest.Dependencies = dependencies;
+                adjust?.Invoke(manifest);
+            });
+        }
+
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="uniqueID">The mod's name and unique ID.</param>
+        /// <param name="version">The mod version.</param>
+        /// <param name="dependencies">The dependencies this mod requires.</param>
+        private IManifest GetManifest(string uniqueID, string version, params IManifestDependency[] dependencies)
+        {
+            return this.GetManifest(uniqueID, version, null, dependencies);
+        }
+
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="uniqueID">The mod's name and unique ID.</param>
+        private Mock<IModMetadata> GetMetadata(string uniqueID)
+        {
+            return this.GetMetadata(this.GetManifest(uniqueID, "1.0"));
+        }
+
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="uniqueID">The mod's name and unique ID.</param>
+        /// <param name="dependencies">The dependencies this mod requires.</param>
+        /// <param name="allowStatusChange">Whether the code being tested is allowed to change the mod status.</param>
+        private Mock<IModMetadata> GetMetadata(string uniqueID, string[] dependencies, bool allowStatusChange = false)
+        {
+            IManifest manifest = this.GetManifest(uniqueID, "1.0", dependencies?.Select(dependencyID => (IManifestDependency)new ManifestDependency(dependencyID, null)).ToArray());
+            return this.GetMetadata(manifest, allowStatusChange);
+        }
+
+        /// <summary>Get a randomised basic manifest.</summary>
+        /// <param name="manifest">The mod manifest.</param>
+        /// <param name="allowStatusChange">Whether the code being tested is allowed to change the mod status.</param>
+        private Mock<IModMetadata> GetMetadata(IManifest manifest, bool allowStatusChange = false)
+        {
+            Mock<IModMetadata> mod = new Mock<IModMetadata>(MockBehavior.Strict);
+            mod.Setup(p => p.DataRecord).Returns(() => null);
+            mod.Setup(p => p.Status).Returns(ModMetadataStatus.Found);
+            mod.Setup(p => p.DisplayName).Returns(manifest.UniqueID);
+            mod.Setup(p => p.Manifest).Returns(manifest);
+            if (allowStatusChange)
+            {
+                mod
+                    .Setup(p => p.SetStatus(It.IsAny<ModMetadataStatus>(), It.IsAny<string>()))
+                    .Callback<ModMetadataStatus, string>((status, message) => Console.WriteLine($"<{manifest.UniqueID} changed status: [{status}] {message}"))
+                    .Returns(mod.Object);
+            }
+            return mod;
+        }
+
+        /// <summary>Set up a mock mod metadata for <see cref="ModResolver.ValidateManifests"/>.</summary>
+        /// <param name="mod">The mock mod metadata.</param>
+        /// <param name="modRecord">The extra metadata about the mod from SMAPI's internal data (if any).</param>
+        private void SetupMetadataForValidation(Mock<IModMetadata> mod, ModDataRecord modRecord = null)
+        {
+            mod.Setup(p => p.Status).Returns(ModMetadataStatus.Found);
+            mod.Setup(p => p.DataRecord).Returns(() => null);
+            mod.Setup(p => p.Manifest).Returns(this.GetManifest());
+            mod.Setup(p => p.DirectoryPath).Returns(Path.GetTempPath());
+            mod.Setup(p => p.DataRecord).Returns(modRecord);
+        }
+    }
+}
diff --git a/src/SMAPI.Tests/Core/TranslationTests.cs b/src/SMAPI.Tests/Core/TranslationTests.cs
new file mode 100644
index 00000000..63404a41
--- /dev/null
+++ b/src/SMAPI.Tests/Core/TranslationTests.cs
@@ -0,0 +1,356 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using StardewModdingAPI.Framework.ModHelpers;
+using StardewValley;
+
+namespace StardewModdingAPI.Tests.Core
+{
+    /// <summary>Unit tests for <see cref="TranslationHelper"/> and <see cref="Translation"/>.</summary>
+    [TestFixture]
+    public class TranslationTests
+    {
+        /*********
+        ** Data
+        *********/
+        /// <summary>Sample translation text for unit tests.</summary>
+        public static string[] Samples = { null, "", "  ", "boop", "  boop  " };
+
+
+        /*********
+        ** Unit tests
+        *********/
+        /****
+        ** Translation helper
+        ****/
+        [Test(Description = "Assert that the translation helper correctly handles no translations.")]
+        public void Helper_HandlesNoTranslations()
+        {
+            // arrange
+            var data = new Dictionary<string, IDictionary<string, string>>();
+
+            // act
+            ITranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
+            Translation translation = helper.Get("key");
+            Translation[] translationList = helper.GetTranslations()?.ToArray();
+
+            // assert
+            Assert.AreEqual("en", helper.Locale, "The locale doesn't match the input value.");
+            Assert.AreEqual(LocalizedContentManager.LanguageCode.en, helper.LocaleEnum, "The locale enum doesn't match the input value.");
+            Assert.IsNotNull(translationList, "The full list of translations is unexpectedly null.");
+            Assert.AreEqual(0, translationList.Length, "The full list of translations is unexpectedly not empty.");
+
+            Assert.IsNotNull(translation, "The translation helper unexpectedly returned a null translation.");
+            Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value.");
+        }
+
+        [Test(Description = "Assert that the translation helper returns the expected translations correctly.")]
+        public void Helper_GetTranslations_ReturnsExpectedText()
+        {
+            // arrange
+            var data = this.GetSampleData();
+            var expected = this.GetExpectedTranslations();
+
+            // act
+            var actual = new Dictionary<string, Translation[]>();
+            TranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
+            foreach (string locale in expected.Keys)
+            {
+                this.AssertSetLocale(helper, locale, LocalizedContentManager.LanguageCode.en);
+                actual[locale] = helper.GetTranslations()?.ToArray();
+            }
+
+            // assert
+            foreach (string locale in expected.Keys)
+            {
+                Assert.IsNotNull(actual[locale], $"The translations for {locale} is unexpectedly null.");
+                Assert.That(actual[locale], Is.EquivalentTo(expected[locale]).Using<Translation, Translation>(this.CompareEquality), $"The translations for {locale} don't match the expected values.");
+            }
+        }
+
+        [Test(Description = "Assert that the translations returned by the helper has the expected text.")]
+        public void Helper_Get_ReturnsExpectedText()
+        {
+            // arrange
+            var data = this.GetSampleData();
+            var expected = this.GetExpectedTranslations();
+
+            // act
+            var actual = new Dictionary<string, Translation[]>();
+            TranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
+            foreach (string locale in expected.Keys)
+            {
+                this.AssertSetLocale(helper, locale, LocalizedContentManager.LanguageCode.en);
+
+                List<Translation> translations = new List<Translation>();
+                foreach (Translation translation in expected[locale])
+                    translations.Add(helper.Get(translation.Key));
+                actual[locale] = translations.ToArray();
+            }
+
+            // assert
+            foreach (string locale in expected.Keys)
+            {
+                Assert.IsNotNull(actual[locale], $"The translations for {locale} is unexpectedly null.");
+                Assert.That(actual[locale], Is.EquivalentTo(expected[locale]).Using<Translation, Translation>(this.CompareEquality), $"The translations for {locale} don't match the expected values.");
+            }
+        }
+
+        /****
+        ** Translation
+        ****/
+        [Test(Description = "Assert that HasValue returns the expected result for various inputs.")]
+        [TestCase(null, ExpectedResult = false)]
+        [TestCase("", ExpectedResult = false)]
+        [TestCase("  ", ExpectedResult = true)]
+        [TestCase("boop", ExpectedResult = true)]
+        [TestCase("  boop  ", ExpectedResult = true)]
+        public bool Translation_HasValue(string text)
+        {
+            return new Translation("ModName", "pt-BR", "key", text).HasValue();
+        }
+
+        [Test(Description = "Assert that the translation's ToString method returns the expected text for various inputs.")]
+        public void Translation_ToString([ValueSource(nameof(TranslationTests.Samples))] string text)
+        {
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text);
+
+            // assert
+            if (translation.HasValue())
+                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid input.");
+            else
+                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty input.");
+        }
+
+        [Test(Description = "Assert that the translation's implicit string conversion returns the expected text for various inputs.")]
+        public void Translation_ImplicitStringConversion([ValueSource(nameof(TranslationTests.Samples))] string text)
+        {
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text);
+
+            // assert
+            if (translation.HasValue())
+                Assert.AreEqual(text, (string)translation, "The translation returned an unexpected value given a valid input.");
+            else
+                Assert.AreEqual(this.GetPlaceholderText("key"), (string)translation, "The translation returned an unexpected value given a null or empty input.");
+        }
+
+        [Test(Description = "Assert that the translation returns the expected text given a use-placeholder setting.")]
+        public void Translation_UsePlaceholder([Values(true, false)] bool value, [ValueSource(nameof(TranslationTests.Samples))] string text)
+        {
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text).UsePlaceholder(value);
+
+            // assert
+            if (translation.HasValue())
+                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid input.");
+            else if (!value)
+                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a null or empty input with the placeholder disabled.");
+            else
+                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty input with the placeholder enabled.");
+        }
+
+        [Test(Description = "Assert that the translation's Assert method throws the expected exception.")]
+        public void Translation_Assert([ValueSource(nameof(TranslationTests.Samples))] string text)
+        {
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text);
+
+            // assert
+            if (translation.HasValue())
+                Assert.That(() => translation.Assert(), Throws.Nothing, "The assert unexpected threw an exception for a valid input.");
+            else
+                Assert.That(() => translation.Assert(), Throws.Exception.TypeOf<KeyNotFoundException>(), "The assert didn't throw an exception for invalid input.");
+        }
+
+        [Test(Description = "Assert that the translation returns the expected text after setting the default.")]
+        public void Translation_Default([ValueSource(nameof(TranslationTests.Samples))] string text, [ValueSource(nameof(TranslationTests.Samples))] string @default)
+        {
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text).Default(@default);
+
+            // assert
+            if (!string.IsNullOrEmpty(text))
+                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
+            else if (!string.IsNullOrEmpty(@default))
+                Assert.AreEqual(@default, translation.ToString(), "The translation returned an unexpected value given a null or empty base text, but valid default.");
+            else
+                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty base and default text.");
+        }
+
+        /****
+        ** Translation tokens
+        ****/
+        [Test(Description = "Assert that multiple translation tokens are replaced correctly regardless of the token structure.")]
+        public void Translation_Tokens([Values("anonymous object", "class", "IDictionary<string, object>", "IDictionary<string, string>")] string structure)
+        {
+            // arrange
+            string start = Guid.NewGuid().ToString("N");
+            string middle = Guid.NewGuid().ToString("N");
+            string end = Guid.NewGuid().ToString("N");
+            const string input = "{{start}} tokens are properly replaced (including {{middle}} {{  MIDdlE}}) {{end}}";
+            string expected = $"{start} tokens are properly replaced (including {middle} {middle}) {end}";
+
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", input);
+            switch (structure)
+            {
+                case "anonymous object":
+                    translation = translation.Tokens(new { start, middle, end });
+                    break;
+
+                case "class":
+                    translation = translation.Tokens(new TokenModel { Start = start, Middle = middle, End = end });
+                    break;
+
+                case "IDictionary<string, object>":
+                    translation = translation.Tokens(new Dictionary<string, object> { ["start"] = start, ["middle"] = middle, ["end"] = end });
+                    break;
+
+                case "IDictionary<string, string>":
+                    translation = translation.Tokens(new Dictionary<string, string> { ["start"] = start, ["middle"] = middle, ["end"] = end });
+                    break;
+
+                default:
+                    throw new NotSupportedException($"Unknown structure '{structure}'.");
+            }
+
+            // assert
+            Assert.AreEqual(expected, translation.ToString(), "The translation returned an unexpected text.");
+        }
+
+        [Test(Description = "Assert that the translation can replace tokens in all valid formats.")]
+        [TestCase("{{value}}", "value")]
+        [TestCase("{{ value }}", "value")]
+        [TestCase("{{value       }}", "value")]
+        [TestCase("{{ the_value }}", "the_value")]
+        [TestCase("{{ the.value_here }}", "the.value_here")]
+        [TestCase("{{ the_value-here.... }}", "the_value-here....")]
+        [TestCase("{{ tHe_vALuE-HEre.... }}", "tHe_vALuE-HEre....")]
+        public void Translation_Tokens_ValidFormats(string text, string key)
+        {
+            // arrange
+            string value = Guid.NewGuid().ToString("N");
+
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text).Tokens(new Dictionary<string, object> { [key] = value });
+
+            // assert
+            Assert.AreEqual(value, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
+        }
+
+        [Test(Description = "Assert that translation tokens are case-insensitive and surrounding-whitespace-insensitive.")]
+        [TestCase("{{value}}", "value")]
+        [TestCase("{{VaLuE}}", "vAlUe")]
+        [TestCase("{{VaLuE   }}", "   vAlUe")]
+        public void Translation_Tokens_KeysAreNormalised(string text, string key)
+        {
+            // arrange
+            string value = Guid.NewGuid().ToString("N");
+
+            // act
+            Translation translation = new Translation("ModName", "pt-BR", "key", text).Tokens(new Dictionary<string, object> { [key] = value });
+
+            // assert
+            Assert.AreEqual(value, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Set a translation helper's locale and assert that it was set correctly.</summary>
+        /// <param name="helper">The translation helper to change.</param>
+        /// <param name="locale">The expected locale.</param>
+        /// <param name="localeEnum">The expected game language code.</param>
+        private void AssertSetLocale(TranslationHelper helper, string locale, LocalizedContentManager.LanguageCode localeEnum)
+        {
+            helper.SetLocale(locale, localeEnum);
+            Assert.AreEqual(locale, helper.Locale, "The locale doesn't match the input value.");
+            Assert.AreEqual(localeEnum, helper.LocaleEnum, "The locale enum doesn't match the input value.");
+        }
+
+        /// <summary>Get sample raw translations to input.</summary>
+        private IDictionary<string, IDictionary<string, string>> GetSampleData()
+        {
+            return new Dictionary<string, IDictionary<string, string>>
+            {
+                ["default"] = new Dictionary<string, string>
+                {
+                    ["key A"] = "default A",
+                    ["key C"] = "default C"
+                },
+                ["en"] = new Dictionary<string, string>
+                {
+                    ["key A"] = "en A",
+                    ["key B"] = "en B"
+                },
+                ["en-US"] = new Dictionary<string, string>(),
+                ["zzz"] = new Dictionary<string, string>
+                {
+                    ["key A"] = "zzz A"
+                }
+            };
+        }
+
+        /// <summary>Get the expected translation output given <see cref="TranslationTests.GetSampleData"/>, based on the expected locale fallback.</summary>
+        private IDictionary<string, Translation[]> GetExpectedTranslations()
+        {
+            var expected = new Dictionary<string, Translation[]>
+            {
+                ["default"] = new[]
+                {
+                    new Translation(string.Empty, "default", "key A", "default A"),
+                    new Translation(string.Empty, "default", "key C", "default C")
+                },
+                ["en"] = new[]
+                {
+                    new Translation(string.Empty, "en", "key A", "en A"),
+                    new Translation(string.Empty, "en", "key B", "en B"),
+                    new Translation(string.Empty, "en", "key C", "default C")
+                },
+                ["zzz"] = new[]
+                {
+                    new Translation(string.Empty, "zzz", "key A", "zzz A"),
+                    new Translation(string.Empty, "zzz", "key C", "default C")
+                }
+            };
+            expected["en-us"] = expected["en"].ToArray();
+            return expected;
+        }
+
+        /// <summary>Get whether two translations have the same public values.</summary>
+        /// <param name="a">The first translation to compare.</param>
+        /// <param name="b">The second translation to compare.</param>
+        private bool CompareEquality(Translation a, Translation b)
+        {
+            return a.Key == b.Key && a.ToString() == b.ToString();
+        }
+
+        /// <summary>Get the default placeholder text when a translation is missing.</summary>
+        /// <param name="key">The translation key.</param>
+        private string GetPlaceholderText(string key)
+        {
+            return string.Format(Translation.PlaceholderText, key);
+        }
+
+
+        /*********
+        ** Test models
+        *********/
+        /// <summary>A model used to test token support.</summary>
+        private class TokenModel
+        {
+            /// <summary>A sample token property.</summary>
+            public string Start { get; set; }
+
+            /// <summary>A sample token property.</summary>
+            public string Middle { get; set; }
+
+            /// <summary>A sample token field.</summary>
+            public string End;
+        }
+    }
+}
diff --git a/src/SMAPI.Tests/Properties/AssemblyInfo.cs b/src/SMAPI.Tests/Properties/AssemblyInfo.cs
new file mode 100644
index 00000000..ee09145b
--- /dev/null
+++ b/src/SMAPI.Tests/Properties/AssemblyInfo.cs
@@ -0,0 +1,6 @@
+using System.Reflection;
+using System.Runtime.InteropServices;
+
+[assembly: AssemblyTitle("StardewModdingAPI.Tests")]
+[assembly: AssemblyDescription("")]
+[assembly: Guid("36ccb19e-92eb-48c7-9615-98eefd45109b")]
diff --git a/src/SMAPI.Tests/Sample.cs b/src/SMAPI.Tests/Sample.cs
new file mode 100644
index 00000000..99835d92
--- /dev/null
+++ b/src/SMAPI.Tests/Sample.cs
@@ -0,0 +1,30 @@
+using System;
+
+namespace StardewModdingAPI.Tests
+{
+    /// <summary>Provides sample values for unit testing.</summary>
+    internal static class Sample
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>A random number generator.</summary>
+        private static readonly Random Random = new Random();
+
+
+        /*********
+        ** Properties
+        *********/
+        /// <summary>Get a sample string.</summary>
+        public static string String()
+        {
+            return Guid.NewGuid().ToString("N");
+        }
+
+        /// <summary>Get a sample integer.</summary>
+        public static int Int()
+        {
+            return Sample.Random.Next();
+        }
+    }
+}
diff --git a/src/SMAPI.Tests/StardewModdingAPI.Tests.csproj b/src/SMAPI.Tests/StardewModdingAPI.Tests.csproj
new file mode 100644
index 00000000..42c3318f
--- /dev/null
+++ b/src/SMAPI.Tests/StardewModdingAPI.Tests.csproj
@@ -0,0 +1,69 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <ProjectGuid>{36CCB19E-92EB-48C7-9615-98EEFD45109B}</ProjectGuid>
+    <OutputType>Library</OutputType>
+    <AppDesignerFolder>Properties</AppDesignerFolder>
+    <RootNamespace>StardewModdingAPI.Tests</RootNamespace>
+    <AssemblyName>StardewModdingAPI.Tests</AssemblyName>
+    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <FileAlignment>512</FileAlignment>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug\</OutputPath>
+    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
+    <DebugType>pdbonly</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release\</OutputPath>
+    <DefineConstants>TRACE</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="Castle.Core, Version=4.1.1.0, Culture=neutral, PublicKeyToken=407dd0808d44fbdc, processorArchitecture=MSIL">
+      <HintPath>..\packages\Castle.Core.4.1.1\lib\net45\Castle.Core.dll</HintPath>
+    </Reference>
+    <Reference Include="Moq, Version=4.7.99.0, Culture=neutral, PublicKeyToken=69f491c39445e920, processorArchitecture=MSIL">
+      <HintPath>..\packages\Moq.4.7.99\lib\net45\Moq.dll</HintPath>
+    </Reference>
+    <Reference Include="Newtonsoft.Json, Version=8.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
+      <HintPath>..\packages\Newtonsoft.Json.8.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
+    </Reference>
+    <Reference Include="nunit.framework, Version=3.8.1.0, Culture=neutral, PublicKeyToken=2638cd05610744eb, processorArchitecture=MSIL">
+      <HintPath>..\packages\NUnit.3.8.1\lib\net45\nunit.framework.dll</HintPath>
+    </Reference>
+    <Reference Include="System" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="..\..\build\GlobalAssemblyInfo.cs">
+      <Link>Properties\GlobalAssemblyInfo.cs</Link>
+    </Compile>
+    <Compile Include="Utilities\SemanticVersionTests.cs" />
+    <Compile Include="Utilities\SDateTests.cs" />
+    <Compile Include="Core\TranslationTests.cs" />
+    <Compile Include="Core\ModResolverTests.cs" />
+    <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Sample.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="packages.config" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\SMAPI\StardewModdingAPI.csproj">
+      <Project>{f1a573b0-f436-472c-ae29-0b91ea6b9f8f}</Project>
+      <Name>StardewModdingAPI</Name>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <Import Project="..\..\build\common.targets" />
+</Project>
\ No newline at end of file
diff --git a/src/SMAPI.Tests/Utilities/SDateTests.cs b/src/SMAPI.Tests/Utilities/SDateTests.cs
new file mode 100644
index 00000000..25acbaf3
--- /dev/null
+++ b/src/SMAPI.Tests/Utilities/SDateTests.cs
@@ -0,0 +1,255 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Text.RegularExpressions;
+using NUnit.Framework;
+using StardewModdingAPI.Utilities;
+
+namespace StardewModdingAPI.Tests.Utilities
+{
+    /// <summary>Unit tests for <see cref="SDate"/>.</summary>
+    [TestFixture]
+    internal class SDateTests
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>All valid seasons.</summary>
+        private static readonly string[] ValidSeasons = { "spring", "summer", "fall", "winter" };
+
+        /// <summary>All valid days of a month.</summary>
+        private static readonly int[] ValidDays = Enumerable.Range(1, 28).ToArray();
+
+        /// <summary>Sample relative dates for test cases.</summary>
+        private static class Dates
+        {
+            /// <summary>The base date to which other dates are relative.</summary>
+            public const string Now = "02 summer Y2";
+
+            /// <summary>The day before <see cref="Now"/>.</summary>
+            public const string PrevDay = "01 summer Y2";
+
+            /// <summary>The month before <see cref="Now"/>.</summary>
+            public const string PrevMonth = "02 spring Y2";
+
+            /// <summary>The year before <see cref="Now"/>.</summary>
+            public const string PrevYear = "02 summer Y1";
+
+            /// <summary>The day after <see cref="Now"/>.</summary>
+            public const string NextDay = "03 summer Y2";
+
+            /// <summary>The month after <see cref="Now"/>.</summary>
+            public const string NextMonth = "02 fall Y2";
+
+            /// <summary>The year after <see cref="Now"/>.</summary>
+            public const string NextYear = "02 summer Y3";
+        }
+
+
+        /*********
+        ** Unit tests
+        *********/
+        /****
+        ** Constructor
+        ****/
+        [Test(Description = "Assert that the constructor sets the expected values for all valid dates.")]
+        public void Constructor_SetsExpectedValues([ValueSource(nameof(SDateTests.ValidSeasons))] string season, [ValueSource(nameof(SDateTests.ValidDays))] int day, [Values(1, 2, 100)] int year)
+        {
+            // act
+            SDate date = new SDate(day, season, year);
+
+            // assert
+            Assert.AreEqual(day, date.Day);
+            Assert.AreEqual(season, date.Season);
+            Assert.AreEqual(year, date.Year);
+        }
+
+        [Test(Description = "Assert that the constructor throws an exception if the values are invalid.")]
+        [TestCase(01, "Spring", 1)] // seasons are case-sensitive
+        [TestCase(01, "springs", 1)] // invalid season name
+        [TestCase(-1, "spring", 1)] // day < 0
+        [TestCase(29, "spring", 1)] // day > 28
+        [TestCase(01, "spring", -1)] // year < 1
+        [TestCase(01, "spring", 0)] // year < 1
+        [SuppressMessage("ReSharper", "AssignmentIsFullyDiscarded", Justification = "Deliberate for unit test.")]
+        public void Constructor_RejectsInvalidValues(int day, string season, int year)
+        {
+            // act & assert
+            Assert.Throws<ArgumentException>(() => _ = new SDate(day, season, year), "Constructing the invalid date didn't throw the expected exception.");
+        }
+
+        /****
+        ** ToString
+        ****/
+        [Test(Description = "Assert that ToString returns the expected string.")]
+        [TestCase("14 spring Y1", ExpectedResult = "14 spring Y1")]
+        [TestCase("01 summer Y16", ExpectedResult = "01 summer Y16")]
+        [TestCase("28 fall Y10", ExpectedResult = "28 fall Y10")]
+        [TestCase("01 winter Y1", ExpectedResult = "01 winter Y1")]
+        public string ToString(string dateStr)
+        {
+            return this.GetDate(dateStr).ToString();
+        }
+
+        /****
+        ** AddDays
+        ****/
+        [Test(Description = "Assert that AddDays returns the expected date.")]
+        [TestCase("01 spring Y1", 15, ExpectedResult = "16 spring Y1")] // day transition
+        [TestCase("01 spring Y1", 28, ExpectedResult = "01 summer Y1")] // season transition
+        [TestCase("01 spring Y1", 28 * 4, ExpectedResult = "01 spring Y2")] // year transition
+        [TestCase("01 spring Y1", 28 * 7 + 17, ExpectedResult = "18 winter Y2")] // year transition
+        [TestCase("15 spring Y1", -14, ExpectedResult = "01 spring Y1")] // negative day transition
+        [TestCase("15 summer Y1", -28, ExpectedResult = "15 spring Y1")] // negative season transition
+        [TestCase("15 summer Y2", -28 * 4, ExpectedResult = "15 summer Y1")] // negative year transition
+        [TestCase("01 spring Y3", -(28 * 7 + 17), ExpectedResult = "12 spring Y1")] // negative year transition
+        [TestCase("06 fall Y2", 50, ExpectedResult = "28 winter Y3")] // test for zero-index errors
+        [TestCase("06 fall Y2", 51, ExpectedResult = "01 spring Y3")] // test for zero-index errors
+        public string AddDays(string dateStr, int addDays)
+        {
+            return this.GetDate(dateStr).AddDays(addDays).ToString();
+        }
+
+        /****
+        ** GetHashCode
+        ****/
+        [Test(Description = "Assert that GetHashCode returns a unique ordered value for every date.")]
+        public void GetHashCode_ReturnsUniqueOrderedValue()
+        {
+            IDictionary<int, SDate> hashes = new Dictionary<int, SDate>();
+            int lastHash = int.MinValue;
+            for (int year = 1; year <= 4; year++)
+            {
+                foreach (string season in SDateTests.ValidSeasons)
+                {
+                    foreach (int day in SDateTests.ValidDays)
+                    {
+                        SDate date = new SDate(day, season, year);
+                        int hash = date.GetHashCode();
+                        if (hashes.TryGetValue(hash, out SDate otherDate))
+                            Assert.Fail($"Received identical hash code {hash} for dates {otherDate} and {date}.");
+                        if (hash < lastHash)
+                            Assert.Fail($"Received smaller hash code for date {date} ({hash}) relative to {hashes[lastHash]} ({lastHash}).");
+
+                        lastHash = hash;
+                        hashes[hash] = date;
+                    }
+                }
+            }
+        }
+
+        [Test(Description = "Assert that the == operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = false)]
+        public bool Operators_Equals(string now, string other)
+        {
+            return this.GetDate(now) == this.GetDate(other);
+        }
+
+        [Test(Description = "Assert that the != operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = true)]
+        public bool Operators_NotEquals(string now, string other)
+        {
+            return this.GetDate(now) != this.GetDate(other);
+        }
+
+        [Test(Description = "Assert that the < operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = true)]
+        public bool Operators_LessThan(string now, string other)
+        {
+            return this.GetDate(now) < this.GetDate(other);
+        }
+
+        [Test(Description = "Assert that the <= operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = true)]
+        public bool Operators_LessThanOrEqual(string now, string other)
+        {
+            return this.GetDate(now) <= this.GetDate(other);
+        }
+
+        [Test(Description = "Assert that the > operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = false)]
+        public bool Operators_MoreThan(string now, string other)
+        {
+            return this.GetDate(now) > this.GetDate(other);
+        }
+
+        [Test(Description = "Assert that the > operator returns the expected values. We only need a few test cases, since it's based on GetHashCode which is tested more thoroughly.")]
+        [TestCase(Dates.Now, null, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.PrevDay, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevMonth, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.PrevYear, ExpectedResult = true)]
+        [TestCase(Dates.Now, Dates.Now, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextDay, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextMonth, ExpectedResult = false)]
+        [TestCase(Dates.Now, Dates.NextYear, ExpectedResult = false)]
+        public bool Operators_MoreThanOrEqual(string now, string other)
+        {
+            return this.GetDate(now) > this.GetDate(other);
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Convert a string date into a game date, to make unit tests easier to read.</summary>
+        /// <param name="dateStr">The date string like "dd MMMM yy".</param>
+        private SDate GetDate(string dateStr)
+        {
+            if (dateStr == null)
+                return null;
+
+            void Fail(string reason) => throw new AssertionException($"Couldn't parse date '{dateStr}' because {reason}.");
+
+            // parse
+            Match match = Regex.Match(dateStr, @"^(?<day>\d+) (?<season>\w+) Y(?<year>\d+)$");
+            if (!match.Success)
+                Fail("it doesn't match expected pattern (should be like 28 spring Y1)");
+
+            // extract parts
+            string season = match.Groups["season"].Value;
+            if (!int.TryParse(match.Groups["day"].Value, out int day))
+                Fail($"'{match.Groups["day"].Value}' couldn't be parsed as a day.");
+            if (!int.TryParse(match.Groups["year"].Value, out int year))
+                Fail($"'{match.Groups["year"].Value}' couldn't be parsed as a year.");
+
+            // build date
+            return new SDate(day, season, year);
+        }
+    }
+}
diff --git a/src/SMAPI.Tests/Utilities/SemanticVersionTests.cs b/src/SMAPI.Tests/Utilities/SemanticVersionTests.cs
new file mode 100644
index 00000000..03cd26c9
--- /dev/null
+++ b/src/SMAPI.Tests/Utilities/SemanticVersionTests.cs
@@ -0,0 +1,302 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Newtonsoft.Json;
+using NUnit.Framework;
+using StardewModdingAPI.Framework;
+
+namespace StardewModdingAPI.Tests.Utilities
+{
+    /// <summary>Unit tests for <see cref="SemanticVersion"/>.</summary>
+    [TestFixture]
+    internal class SemanticVersionTests
+    {
+        /*********
+        ** Unit tests
+        *********/
+        /****
+        ** Constructor
+        ****/
+        [Test(Description = "Assert that the constructor sets the expected values for all valid versions.")]
+        [TestCase("1.0", ExpectedResult = "1.0")]
+        [TestCase("1.0.0", ExpectedResult = "1.0")]
+        [TestCase("3000.4000.5000", ExpectedResult = "3000.4000.5000")]
+        [TestCase("1.2-some-tag.4", ExpectedResult = "1.2-some-tag.4")]
+        [TestCase("1.2.3-some-tag.4", ExpectedResult = "1.2.3-some-tag.4")]
+        [TestCase("1.2.3-some-tag.4      ", ExpectedResult = "1.2.3-some-tag.4")]
+        public string Constructor_FromString(string input)
+        {
+            return new SemanticVersion(input).ToString();
+        }
+
+        [Test(Description = "Assert that the constructor sets the expected values for all valid versions.")]
+        [TestCase(1, 0, 0, null, ExpectedResult = "1.0")]
+        [TestCase(3000, 4000, 5000, null, ExpectedResult = "3000.4000.5000")]
+        [TestCase(1, 2, 3, "", ExpectedResult = "1.2.3")]
+        [TestCase(1, 2, 3, "    ", ExpectedResult = "1.2.3")]
+        [TestCase(1, 2, 3, "some-tag.4", ExpectedResult = "1.2.3-some-tag.4")]
+        [TestCase(1, 2, 3, "some-tag.4   ", ExpectedResult = "1.2.3-some-tag.4")]
+        public string Constructor_FromParts(int major, int minor, int patch, string tag)
+        {
+            // act
+            ISemanticVersion version = new SemanticVersion(major, minor, patch, tag);
+
+            // assert
+            Assert.AreEqual(major, version.MajorVersion, "The major version doesn't match the given value.");
+            Assert.AreEqual(minor, version.MinorVersion, "The minor version doesn't match the given value.");
+            Assert.AreEqual(patch, version.PatchVersion, "The patch version doesn't match the given value.");
+            Assert.AreEqual(string.IsNullOrWhiteSpace(tag) ? null : tag.Trim(), version.Build, "The tag doesn't match the given value.");
+            return version.ToString();
+        }
+
+        [Test(Description = "Assert that the constructor throws the expected exception for invalid versions.")]
+        [TestCase(null)]
+        [TestCase("")]
+        [TestCase("   ")]
+        [TestCase("1")]
+        [TestCase("01.0")]
+        [TestCase("1.05")]
+        [TestCase("1.5.06")] // leading zeros specifically prohibited by spec
+        [TestCase("1.2.3.4")]
+        [TestCase("1.apple")]
+        [TestCase("1.2.apple")]
+        [TestCase("1.2.3.apple")]
+        [TestCase("1..2..3")]
+        [TestCase("1.2.3-")]
+        [TestCase("1.2.3-some-tag...")]
+        [TestCase("1.2.3-some-tag...4")]
+        [TestCase("apple")]
+        [TestCase("-apple")]
+        [TestCase("-5")]
+        public void Constructor_FromString_WithInvalidValues(string input)
+        {
+            if (input == null)
+                this.AssertAndLogException<ArgumentNullException>(() => new SemanticVersion(input));
+            else
+                this.AssertAndLogException<FormatException>(() => new SemanticVersion(input));
+        }
+
+        /****
+        ** CompareTo
+        ****/
+        [Test(Description = "Assert that version.CompareTo returns the expected value.")]
+        // equal
+        [TestCase("0.5.7", "0.5.7", ExpectedResult = 0)]
+        [TestCase("1.0", "1.0", ExpectedResult = 0)]
+        [TestCase("1.0-beta", "1.0-beta", ExpectedResult = 0)]
+        [TestCase("1.0-beta.10", "1.0-beta.10", ExpectedResult = 0)]
+        [TestCase("1.0-beta", "1.0-beta   ", ExpectedResult = 0)]
+
+        // less than
+        [TestCase("0.5.7", "0.5.8", ExpectedResult = -1)]
+        [TestCase("1.0", "1.1", ExpectedResult = -1)]
+        [TestCase("1.0-beta", "1.0", ExpectedResult = -1)]
+        [TestCase("1.0-beta", "1.0-beta.2", ExpectedResult = -1)]
+        [TestCase("1.0-beta.1", "1.0-beta.2", ExpectedResult = -1)]
+        [TestCase("1.0-beta.2", "1.0-beta.10", ExpectedResult = -1)]
+        [TestCase("1.0-beta-2", "1.0-beta-10", ExpectedResult = -1)]
+
+        // more than
+        [TestCase("0.5.8", "0.5.7", ExpectedResult = 1)]
+        [TestCase("1.1", "1.0", ExpectedResult = 1)]
+        [TestCase("1.0", "1.0-beta", ExpectedResult = 1)]
+        [TestCase("1.0-beta.2", "1.0-beta", ExpectedResult = 1)]
+        [TestCase("1.0-beta.2", "1.0-beta.1", ExpectedResult = 1)]
+        [TestCase("1.0-beta.10", "1.0-beta.2", ExpectedResult = 1)]
+        [TestCase("1.0-beta-10", "1.0-beta-2", ExpectedResult = 1)]
+        public int CompareTo(string versionStrA, string versionStrB)
+        {
+            ISemanticVersion versionA = new SemanticVersion(versionStrA);
+            ISemanticVersion versionB = new SemanticVersion(versionStrB);
+            return versionA.CompareTo(versionB);
+        }
+
+        /****
+        ** IsOlderThan
+        ****/
+        [Test(Description = "Assert that version.IsOlderThan returns the expected value.")]
+        // keep test cases in sync with CompareTo for simplicity.
+        // equal
+        [TestCase("0.5.7", "0.5.7", ExpectedResult = false)]
+        [TestCase("1.0", "1.0", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0-beta", ExpectedResult = false)]
+        [TestCase("1.0-beta.10", "1.0-beta.10", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0-beta   ", ExpectedResult = false)]
+
+        // less than
+        [TestCase("0.5.7", "0.5.8", ExpectedResult = true)]
+        [TestCase("1.0", "1.1", ExpectedResult = true)]
+        [TestCase("1.0-beta", "1.0", ExpectedResult = true)]
+        [TestCase("1.0-beta", "1.0-beta.2", ExpectedResult = true)]
+        [TestCase("1.0-beta.1", "1.0-beta.2", ExpectedResult = true)]
+        [TestCase("1.0-beta.2", "1.0-beta.10", ExpectedResult = true)]
+        [TestCase("1.0-beta-2", "1.0-beta-10", ExpectedResult = true)]
+
+        // more than
+        [TestCase("0.5.8", "0.5.7", ExpectedResult = false)]
+        [TestCase("1.1", "1.0", ExpectedResult = false)]
+        [TestCase("1.0", "1.0-beta", ExpectedResult = false)]
+        [TestCase("1.0-beta.2", "1.0-beta", ExpectedResult = false)]
+        [TestCase("1.0-beta.2", "1.0-beta.1", ExpectedResult = false)]
+        [TestCase("1.0-beta.10", "1.0-beta.2", ExpectedResult = false)]
+        [TestCase("1.0-beta-10", "1.0-beta-2", ExpectedResult = false)]
+        public bool IsOlderThan(string versionStrA, string versionStrB)
+        {
+            ISemanticVersion versionA = new SemanticVersion(versionStrA);
+            ISemanticVersion versionB = new SemanticVersion(versionStrB);
+            return versionA.IsOlderThan(versionB);
+        }
+
+        /****
+        ** IsNewerThan
+        ****/
+        [Test(Description = "Assert that version.IsNewerThan returns the expected value.")]
+        // keep test cases in sync with CompareTo for simplicity.
+        // equal
+        [TestCase("0.5.7", "0.5.7", ExpectedResult = false)]
+        [TestCase("1.0", "1.0", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0-beta", ExpectedResult = false)]
+        [TestCase("1.0-beta.10", "1.0-beta.10", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0-beta   ", ExpectedResult = false)]
+
+        // less than
+        [TestCase("0.5.7", "0.5.8", ExpectedResult = false)]
+        [TestCase("1.0", "1.1", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0", ExpectedResult = false)]
+        [TestCase("1.0-beta", "1.0-beta.2", ExpectedResult = false)]
+        [TestCase("1.0-beta.1", "1.0-beta.2", ExpectedResult = false)]
+        [TestCase("1.0-beta.2", "1.0-beta.10", ExpectedResult = false)]
+        [TestCase("1.0-beta-2", "1.0-beta-10", ExpectedResult = false)]
+
+        // more than
+        [TestCase("0.5.8", "0.5.7", ExpectedResult = true)]
+        [TestCase("1.1", "1.0", ExpectedResult = true)]
+        [TestCase("1.0", "1.0-beta", ExpectedResult = true)]
+        [TestCase("1.0-beta.2", "1.0-beta", ExpectedResult = true)]
+        [TestCase("1.0-beta.2", "1.0-beta.1", ExpectedResult = true)]
+        [TestCase("1.0-beta.10", "1.0-beta.2", ExpectedResult = true)]
+        [TestCase("1.0-beta-10", "1.0-beta-2", ExpectedResult = true)]
+        public bool IsNewerThan(string versionStrA, string versionStrB)
+        {
+            ISemanticVersion versionA = new SemanticVersion(versionStrA);
+            ISemanticVersion versionB = new SemanticVersion(versionStrB);
+            return versionA.IsNewerThan(versionB);
+        }
+
+        /****
+        ** IsBetween
+        ****/
+        [Test(Description = "Assert that version.IsNewerThan returns the expected value.")]
+        // is between
+        [TestCase("0.5.7-beta.3", "0.5.7-beta.3", "0.5.7-beta.3", ExpectedResult = true)]
+        [TestCase("1.0", "1.0", "1.1", ExpectedResult = true)]
+        [TestCase("1.0", "1.0-beta", "1.1", ExpectedResult = true)]
+        [TestCase("1.0", "0.5", "1.1", ExpectedResult = true)]
+        [TestCase("1.0-beta.2", "1.0-beta.1", "1.0-beta.3", ExpectedResult = true)]
+        [TestCase("1.0-beta-2", "1.0-beta-1", "1.0-beta-3", ExpectedResult = true)]
+
+        // is not between
+        [TestCase("1.0-beta", "1.0", "1.1", ExpectedResult = false)]
+        [TestCase("1.0", "1.1", "1.0", ExpectedResult = false)]
+        [TestCase("1.0-beta.2", "1.1", "1.0", ExpectedResult = false)]
+        [TestCase("1.0-beta.2", "1.0-beta.10", "1.0-beta.3", ExpectedResult = false)]
+        [TestCase("1.0-beta-2", "1.0-beta-10", "1.0-beta-3", ExpectedResult = false)]
+        public bool IsBetween(string versionStr, string lowerStr, string upperStr)
+        {
+            ISemanticVersion lower = new SemanticVersion(lowerStr);
+            ISemanticVersion upper = new SemanticVersion(upperStr);
+            ISemanticVersion version = new SemanticVersion(versionStr);
+            return version.IsBetween(lower, upper);
+        }
+
+        /****
+        ** Serialisable
+        ****/
+        [Test(Description = "Assert that SemanticVersion can be round-tripped through JSON with no special configuration.")]
+        [TestCase("1.0")]
+        public void Serialisable(string versionStr)
+        {
+            // act
+            string json = JsonConvert.SerializeObject(new SemanticVersion(versionStr));
+            SemanticVersion after = JsonConvert.DeserializeObject<SemanticVersion>(json);
+
+            // assert
+            Assert.IsNotNull(after, "The semantic version after deserialisation is unexpectedly null.");
+            Assert.AreEqual(versionStr, after.ToString(), "The semantic version after deserialisation doesn't match the input version.");
+        }
+
+        /****
+        ** GameVersion
+        ****/
+        [Test(Description = "Assert that the GameVersion subclass correctly parses legacy game versions.")]
+        [TestCase("1.0")]
+        [TestCase("1.01")]
+        [TestCase("1.02")]
+        [TestCase("1.03")]
+        [TestCase("1.04")]
+        [TestCase("1.05")]
+        [TestCase("1.051")]
+        [TestCase("1.051b")]
+        [TestCase("1.06")]
+        [TestCase("1.07")]
+        [TestCase("1.07a")]
+        [TestCase("1.1")]
+        [TestCase("1.11")]
+        [TestCase("1.2")]
+        [TestCase("1.2.15")]
+        public void GameVersion(string versionStr)
+        {
+            // act
+            GameVersion version = new GameVersion(versionStr);
+
+            // assert
+            Assert.AreEqual(versionStr, version.ToString(), "The game version did not round-trip to the same value.");
+            Assert.IsTrue(version.IsOlderThan(new SemanticVersion("1.2.30")), "The game version should be considered older than the later semantic versions.");
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>Assert that the expected exception type is thrown, and log the action output and thrown exception.</summary>
+        /// <typeparam name="T">The expected exception type.</typeparam>
+        /// <param name="action">The action which may throw the exception.</param>
+        /// <param name="message">The message to log if the expected exception isn't thrown.</param>
+        [SuppressMessage("ReSharper", "UnusedParameter.Local", Justification = "The message argument is deliberately only used in precondition checks since this is an assertion method.")]
+        private void AssertAndLogException<T>(Func<object> action, string message = null)
+            where T : Exception
+        {
+            this.AssertAndLogException<T>(() =>
+            {
+                object result = action();
+                TestContext.WriteLine($"Func result: {result}");
+            });
+        }
+
+        /// <summary>Assert that the expected exception type is thrown, and log the thrown exception.</summary>
+        /// <typeparam name="T">The expected exception type.</typeparam>
+        /// <param name="action">The action which may throw the exception.</param>
+        /// <param name="message">The message to log if the expected exception isn't thrown.</param>
+        [SuppressMessage("ReSharper", "UnusedParameter.Local", Justification = "The message argument is deliberately only used in precondition checks since this is an assertion method.")]
+        private void AssertAndLogException<T>(Action action, string message = null)
+            where T : Exception
+        {
+            try
+            {
+                action();
+            }
+            catch (T ex)
+            {
+                TestContext.WriteLine($"Exception thrown:\n{ex}");
+                return;
+            }
+            catch (Exception ex) when (!(ex is AssertionException))
+            {
+                TestContext.WriteLine($"Exception thrown:\n{ex}");
+                Assert.Fail(message ?? $"Didn't throw the expected exception; expected {typeof(T).FullName}, got {ex.GetType().FullName}.");
+            }
+
+            // no exception thrown
+            Assert.Fail(message ?? "Didn't throw an exception.");
+        }
+    }
+}
diff --git a/src/SMAPI.Tests/packages.config b/src/SMAPI.Tests/packages.config
new file mode 100644
index 00000000..5fdfebdb
--- /dev/null
+++ b/src/SMAPI.Tests/packages.config
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Castle.Core" version="4.1.1" targetFramework="net45" />
+  <package id="Moq" version="4.7.99" targetFramework="net45" />
+  <package id="Newtonsoft.Json" version="8.0.3" targetFramework="net45" />
+  <package id="NUnit" version="3.8.1" targetFramework="net45" />
+</packages>