feat: Adds incremental build and build cache support for the `fregeCompile` task

5 files changed, 53 insertions, 7 deletions

diff --git a/README.md b/README.md
index db18bea..e7a9588 100644
--- a/README.md
+++ b/README.md
@@ -30,15 +30,16 @@ Optional configuration parameters inside `build.gradle`:
 - outputDir: defaults to `<projectRoot>/build/classes/main/frege`
 - compilerFlags: defaults to `['-O', '-make']`
 
-
-
-
 ### Added Tasks
 
 - **setupFrege**: Downloads the specified version of the Frege compiler.
 - **compileFrege**: All your `*.fr` files in `mainSourceDir` get compiled to `outputDir`.
 - **runFrege**: Runs the Frege module specified by `mainModule`. Alternatively you can also pass the main module by command line, e.g: `gradle runFrege --mainModule=my.mod.Name`.
 
+### Build Cache
+
+The `compileFrege` task supports incremental builds from build cache. Enable the build cache by setting `org.gradle.caching=true` in your `gradle.properites`.
+
 
 ## How to Contribute
 Try to add another task, e.g. `fregeDoc` to the [FregePluginFunctionalTest.java](src/functionalTest/java/ch/fhnw/thga/gradleplugins/FregePluginFunctionalTest.java) file and try to make the test pass.
\ No newline at end of file
diff --git a/gradle.properties b/gradle.properties
index 8d4b418..ebaac6f 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,2 +1,2 @@
 group = ch.fhnw.thga
-version = 1.2.0-alpha
\ No newline at end of file
+version = 1.3.0-alpha
\ No newline at end of file
diff --git a/src/functionalTest/java/ch/fhnw/thga/gradleplugins/FregePluginFunctionalTest.java b/src/functionalTest/java/ch/fhnw/thga/gradleplugins/FregePluginFunctionalTest.java
index 78076a9..0cd2561 100644
--- a/src/functionalTest/java/ch/fhnw/thga/gradleplugins/FregePluginFunctionalTest.java
+++ b/src/functionalTest/java/ch/fhnw/thga/gradleplugins/FregePluginFunctionalTest.java
@@ -5,6 +5,8 @@ import static ch.fhnw.thga.gradleplugins.FregeExtension.DEFAULT_DOWNLOAD_DIRECTO
 import static ch.fhnw.thga.gradleplugins.FregePlugin.*;
 import static org.gradle.testkit.runner.TaskOutcome.SUCCESS;
 import static org.gradle.testkit.runner.TaskOutcome.FAILED;
+import static org.gradle.testkit.runner.TaskOutcome.UP_TO_DATE;
+import static org.gradle.testkit.runner.TaskOutcome.FROM_CACHE;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -214,6 +216,41 @@ public class FregePluginFunctionalTest {
             assertTrue(
                     new File(testProjectDir.getAbsolutePath() + "/build/frege/ch/fhnw/thga/Completion.class").exists());
         }
+
+        @Test
+        void and_is_up_to_date_given_no_code_changes() throws Exception {
+            String completionFr = "Completion.fr";
+            String minimalBuildFileConfig = createFregeSection(fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
+            setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);
+
+            BuildResult first = runGradleTask(COMPILE_FREGE_TASK_NAME);
+            assertEquals(SUCCESS, first.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
+
+            BuildResult second = runGradleTask(COMPILE_FREGE_TASK_NAME);
+            assertEquals(UP_TO_DATE, second.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
+        }
+
+        @Test
+        void and_is_cached_given_cache_hit() throws Exception {
+            String completionFr = "Completion.fr";
+            String minimalBuildFileConfig = createFregeSection(fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
+            setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);
+
+            BuildResult first = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
+            assertEquals(SUCCESS, first.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
+
+            String codeChange = String.join(NEW_LINE, "module ch.fhnw.thga.Completion where",
+            NEW_LINE, NEW_LINE, "  frob :: Int -> (Int, String)", NEW_LINE, "  frob i = (i, \"Frege rocks\")",
+                    NEW_LINE);
+            setupDefaultFregeProjectStructure(codeChange, completionFr, "");
+
+            BuildResult second = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
+            assertEquals(SUCCESS, second.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
+
+            setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, "");
+            BuildResult third = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
+            assertEquals(FROM_CACHE, third.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
+        }
     }
 
     @Nested
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java b/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
index 020bc7c..9dc148f 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/CompileFregeTask.java
@@ -13,21 +13,27 @@ import org.gradle.api.file.RegularFileProperty;
 import org.gradle.api.model.ObjectFactory;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Provider;
+import org.gradle.api.tasks.CacheableTask;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputDirectory;
 import org.gradle.api.tasks.InputFile;
 import org.gradle.api.tasks.Internal;
 import org.gradle.api.tasks.JavaExec;
 import org.gradle.api.tasks.OutputDirectory;
+import org.gradle.api.tasks.PathSensitive;
+import org.gradle.api.tasks.PathSensitivity;
 import org.gradle.api.tasks.TaskAction;
 
+@CacheableTask
 public abstract class CompileFregeTask extends DefaultTask {
     private final JavaExec javaExec;
 
     @InputFile
+    @PathSensitive(PathSensitivity.RELATIVE)
     public abstract RegularFileProperty getFregeCompilerJar();
 
     @InputDirectory
+    @PathSensitive(PathSensitivity.RELATIVE)
     public abstract DirectoryProperty getFregeMainSourceDir();
 
     @Input
@@ -60,4 +66,4 @@ public abstract class CompileFregeTask extends DefaultTask {
                 .flatMap(Collection::stream).collect(Collectors.toList());
         javaExec.setClasspath(getProject().files(getFregeCompilerJar())).setArgs(compilerArgs).exec();
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java b/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
index f134ec2..ea02493 100644
--- a/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
+++ b/src/main/java/ch/fhnw/thga/gradleplugins/FregeExtension.java
@@ -12,6 +12,8 @@ import org.gradle.api.provider.Property;
 public abstract class FregeExtension {
     public static final String DEFAULT_DOWNLOAD_DIRECTORY = "lib";
     public static final String DEFAULT_RELATIVE_OUTPUT_DIR = "classes/main/frege";
+    public static final String DEFAULT_RELATIVE_SOURCE_DIR = "src/main/frege";
+    public static final List<String> DEFAULT_COMPILER_FLAGS = List.of("-O", "-make");
 
     public abstract Property<String> getVersion();
 
@@ -30,8 +32,8 @@ public abstract class FregeExtension {
     @Inject
     public FregeExtension(ProjectLayout projectLayout) {
         getCompilerDownloadDir().convention(projectLayout.getProjectDirectory().dir(DEFAULT_DOWNLOAD_DIRECTORY));
-        getMainSourceDir().convention(projectLayout.getProjectDirectory());
+        getMainSourceDir().convention(projectLayout.getProjectDirectory().dir(DEFAULT_RELATIVE_SOURCE_DIR));
         getOutputDir().convention(projectLayout.getBuildDirectory().dir(DEFAULT_RELATIVE_OUTPUT_DIR));
-        getCompilerFlags().convention(List.of("-O", "-make"));
+        getCompilerFlags().convention(DEFAULT_COMPILER_FLAGS);
     }
 }