1 files changed, 31 insertions, 26 deletions

diff --git a/src/SMAPI.Toolkit/Framework/ManifestValidator.cs b/src/SMAPI.Toolkit/Framework/ManifestValidator.cs
index 62cfd8e9..461dc325 100644
--- a/src/SMAPI.Toolkit/Framework/ManifestValidator.cs
+++ b/src/SMAPI.Toolkit/Framework/ManifestValidator.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using StardewModdingAPI.Toolkit.Utilities;
@@ -8,40 +9,47 @@ namespace StardewModdingAPI.Toolkit.Framework
     /// <summary>Validates manifest fields.</summary>
     public static class ManifestValidator
     {
-        /// <summary>Try to validate a manifest's fields. Fails if any invalid field is found.</summary>
+        /// <summary>Validate a manifest's fields.</summary>
         /// <param name="manifest">The manifest to validate.</param>
-        /// <param name="error">The error message to display to the user.</param>
-        /// <returns>Returns whether the manifest was validated successfully.</returns>
-        public static bool TryValidate(IManifest manifest, out string error)
+        /// <param name="error">The error message indicating why validation failed, if applicable.</param>
+        /// <returns>Returns whether all manifest fields validated successfully.</returns>
+        [SuppressMessage("ReSharper", "ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract", Justification = "This is the method that ensures those annotations are respected.")]
+        public static bool TryValidateFields(IManifest manifest, out string error)
         {
-            // validate DLL / content pack fields
+            //
+            // Note: SMAPI assumes that it can grammatically append the returned sentence in the
+            // form "failed loading <mod> because its <error>". Any errors returned should be valid
+            // in that format, unless the SMAPI call is adjusted accordingly.
+            //
+
             bool hasDll = !string.IsNullOrWhiteSpace(manifest.EntryDll);
             bool isContentPack = manifest.ContentPackFor != null;
 
-            // validate field presence
-            if (!hasDll && !isContentPack)
-            {
-                error = $"manifest has no {nameof(IManifest.EntryDll)} or {nameof(IManifest.ContentPackFor)} field; must specify one.";
-                return false;
-            }
-            if (hasDll && isContentPack)
+            // validate use of EntryDll vs ContentPackFor fields
+            if (hasDll == isContentPack)
             {
-                error = $"manifest sets both {nameof(IManifest.EntryDll)} and {nameof(IManifest.ContentPackFor)}, which are mutually exclusive.";
+                error = hasDll
+                    ? $"manifest sets both {nameof(IManifest.EntryDll)} and {nameof(IManifest.ContentPackFor)}, which are mutually exclusive."
+                    : $"manifest has no {nameof(IManifest.EntryDll)} or {nameof(IManifest.ContentPackFor)} field; must specify one.";
                 return false;
             }
 
-            // validate DLL filename format
-            if (hasDll && manifest.EntryDll!.Intersect(Path.GetInvalidFileNameChars()).Any())
+            // validate EntryDll/ContentPackFor format
+            if (hasDll)
             {
-                error = $"manifest has invalid filename '{manifest.EntryDll}' for the EntryDLL field.";
-                return false;
+                if (manifest.EntryDll!.Intersect(Path.GetInvalidFileNameChars()).Any())
+                {
+                    error = $"manifest has invalid filename '{manifest.EntryDll}' for the {nameof(IManifest.EntryDll)} field.";
+                    return false;
+                }
             }
-
-            // validate content pack ID
-            else if (isContentPack && string.IsNullOrWhiteSpace(manifest.ContentPackFor!.UniqueID))
+            else
             {
-                error = $"manifest declares {nameof(IManifest.ContentPackFor)} without its required {nameof(IManifestContentPackFor.UniqueID)} field.";
-                return false;
+                if (string.IsNullOrWhiteSpace(manifest.ContentPackFor!.UniqueID))
+                {
+                    error = $"manifest declares {nameof(IManifest.ContentPackFor)} without its required {nameof(IManifestContentPackFor.UniqueID)} field.";
+                    return false;
+                }
             }
 
             // validate required fields
@@ -69,24 +77,21 @@ namespace StardewModdingAPI.Toolkit.Framework
                 return false;
             }
 
-            // validate dependencies
+            // validate dependency format
             foreach (IManifestDependency? dependency in manifest.Dependencies)
             {
-                // null dependency
                 if (dependency == null)
                 {
                     error = $"manifest has a null entry under {nameof(IManifest.Dependencies)}.";
                     return false;
                 }
 
-                // missing ID
                 if (string.IsNullOrWhiteSpace(dependency.UniqueID))
                 {
                     error = $"manifest has a {nameof(IManifest.Dependencies)} entry with no {nameof(IManifestDependency.UniqueID)} field.";
                     return false;
                 }
 
-                // invalid ID
                 if (!PathUtilities.IsSlug(dependency.UniqueID))
                 {
                     error = $"manifest has a {nameof(IManifest.Dependencies)} entry with an invalid {nameof(IManifestDependency.UniqueID)} field (IDs must only contain letters, numbers, underscores, periods, or hyphens).";