Implemented removal .css counterpart for deleted sass source file

plugin/src/main/java/org/kravemir/gradle/sass/AbstractSassCompileTask.java

@@ -8,6 +8,7 @@
 import org.gradle.api.tasks.InputFiles;
 import org.gradle.api.tasks.OutputDirectory;
 import org.gradle.api.tasks.TaskAction;
+import org.gradle.api.tasks.incremental.IncrementalTaskInputs;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -47,15 +48,24 @@ FileCollection getInputFiles() {
     }
 
     @TaskAction
-    void compile() throws Exception {
+    void compile(IncrementalTaskInputs incrementalTaskInputs) throws Exception {
         File outputDir = getOutputDirectory();
         outputDir.mkdirs();
 
         Path srcDirPath = getSrcDir().toPath();
 
+        // only delete removed files
+        if(incrementalTaskInputs.isIncremental()) {
+            incrementalTaskInputs.outOfDate(inputFileDetails -> {});
+            incrementalTaskInputs.removed(inputFileDetails -> {
+                File outputFile = getOutputFile(srcDirPath,outputDir,inputFileDetails.getFile());
+                if(outputFile.exists())
+                    outputFile.delete();
+            });
+        }
+
         for(File f : getSassFiles()) {
-            Path relativePath = srcDirPath.relativize(f.toPath());
-            File outputFile = new File(outputDir,relativePath.toString().replaceAll("\\.scss",".css"));
+            File outputFile = getOutputFile(srcDirPath,outputDir,f);
             outputFile.getParentFile().mkdirs();
 
             try(OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(outputFile))) {
@@ -69,6 +79,11 @@ void compile() throws Exception {
         }
     }
 
+    private File getOutputFile(Path srcDirPath, File outputDir, File f) {
+        Path relativePath = srcDirPath.relativize(f.toPath());
+        return new File(outputDir,relativePath.toString().replaceAll("\\.scss",".css"));
+    }
+
     /**
      * @return directory, where compiled CSS files are written
      */

plugin/src/test/java/org/kravemir/gradle/sass/tests/IncrementalTasksTest.java

@@ -0,0 +1,92 @@
+package org.kravemir.gradle.sass.tests;
+
+
+import org.gradle.testkit.runner.BuildResult;
+import org.gradle.testkit.runner.GradleRunner;
+import org.gradle.testkit.runner.TaskOutcome;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * @author Miroslav Kravec
+ */
+public class IncrementalTasksTest {
+
+    @Rule
+    public final TemporaryFolder testProjectDir = new TemporaryFolder();
+
+    private File fooScss;
+
+
+    @Before
+    public void setup() throws IOException {
+        File buildFile = testProjectDir.newFile("build.gradle");
+        writeFile(buildFile, "plugins {\n id 'org.kravemir.gradle.sass'\n }\nsass{\nmain{}}");
+
+        Path mainSassPath = Paths.get(testProjectDir.getRoot().getPath(),"src","main","sass");
+        Files.createDirectories(mainSassPath);
+
+        File mainScss = mainSassPath.resolve("main.scss").toFile();
+        mainScss.createNewFile();
+
+        fooScss = mainSassPath.resolve("foo.scss").toFile();
+        fooScss.createNewFile();
+
+    }
+
+
+    @Test
+    public void testFooDeletion() {
+        BuildResult result = GradleRunner.create()
+                .withProjectDir(testProjectDir.getRoot())
+                .withArguments("mainSass")
+                .withPluginClasspath()
+                .build();
+
+        assertEquals("check that ':mainSass' task succeeded", result.task(":mainSass").getOutcome(), TaskOutcome.SUCCESS);
+
+        Path mainSassBuildRoot = Paths.get(testProjectDir.getRoot().getPath(), "build", "sass", "main");
+        assertTrue(mainSassBuildRoot.resolve(Paths.get("main.css")).toFile().exists());
+        assertTrue(mainSassBuildRoot.resolve(Paths.get("foo.css")).toFile().exists());
+
+        fooScss.delete();
+
+        BuildResult result2 = GradleRunner.create()
+                .withProjectDir(testProjectDir.getRoot())
+                .withArguments("mainSass")
+                .withPluginClasspath()
+                .build();
+
+        assertEquals("check that ':mainSass' task succeeded", result2.task(":mainSass").getOutcome(), TaskOutcome.SUCCESS);
+
+        assertTrue(mainSassBuildRoot.resolve(Paths.get("main.css")).toFile().exists());
+        assertFalse(mainSassBuildRoot.resolve(Paths.get("foo.css")).toFile().exists());
+    }
+
+
+    private void writeFile(File destination, String content) throws IOException {
+        BufferedWriter output = null;
+        try {
+            output = new BufferedWriter(new FileWriter(destination));
+            output.write(content);
+        } finally {
+            if (output != null) {
+                output.close();
+            }
+        }
+    }
+}