fix(abigen-plugin): clear previous task outputs if its inputs have ch…

…anged

Old task outputs are not automatically cleared when task inputs change, leading
to corrupted task cache which includes both new and old task outputs. This is
solved by manually removing old inputs - if any - before storing new ouputs

ethers-abigen-plugin/src/main/kotlin/io/ethers/abigen/plugin/task/EthersAbigenTask.kt

@@ -56,6 +56,15 @@ abstract class EthersAbigenTask @Inject constructor(private val executor: Worker
 
     @TaskAction
     fun run() {
+        // Since the task action is being executed, it means that inputs of the task have been changed. In this case
+        // first delete previous outputs if any exist. This prevents a case where user changes inputs without changing
+        // "destinationDir" and does not run the "clean" task before the next build, and the old outputs are still
+        // present. Gradle task will include both new and old task outputs in the new build cache. Now even if we
+        // manually run "clean" task or delete the old output files, they will always get restored from the build cache.
+        //
+        // Solution: https://discuss.gradle.org/t/is-there-a-way-to-delete-prior-runs-output-for-a-task/28834
+        outputs.previousOutputFiles.forEach { it.delete() }
+
         val destDir = destinationDir.get().asFile
 
         var loaderPrefix = project.path.split(":")

ethers-abigen-plugin/src/test/kotlin/io/ethers/abigen/plugin/EthersAbigenPluginTest.kt

@@ -143,12 +143,64 @@ class EthersAbigenPluginTest : FunSpec({
             val result = runner.withArguments("clean", taskName, "--build-cache", "--info").build()
             result.tasks.filter { it.path.endsWith(taskName) }.forEach { it.outcome shouldBe TaskOutcome.SUCCESS }
 
+            val previousGeneratedFiles = project.layout.buildDirectory.dir(customOutputDir).get().asFile
+                .walkTopDown()
+                .filter(File::isFile)
+                .toList()
+
             val generatedFiles = project.layout.buildDirectory.dir(newOutputDir).get().asFile
                 .walkTopDown()
                 .filter(File::isFile)
                 .toList()
 
+            previousGeneratedFiles.size shouldBe 0
+            generatedFiles.size shouldBe 3
+        }
+
+        test("changing task inputs removes previous outputs and generates new ones") {
+            @Language("gradle")
+            val newBuildFile = """
+                plugins {
+                    id 'base'
+                    id 'org.jetbrains.kotlin.jvm'
+                    id 'io.kriptal.ethers.abigen-plugin'
+                }
+                
+                ethersAbigen {
+                    directorySource('$customAbiPath')
+                    outputDir = '$customOutputDir'
+                }
+            """.trimIndent()
+
+            project.layout.projectDirectory.file("build.gradle").asFile.writeText(newBuildFile)
+
+            // old task results are loaded from cache
+            val oldResult = runner.withArguments(taskName, "--build-cache", "--info").build()
+            oldResult.tasks.filter { it.path.endsWith(taskName) }.forEach { it.outcome shouldBe TaskOutcome.FROM_CACHE }
+
+            val oldGeneratedFiles = project.layout.buildDirectory.dir(customOutputDir).get().asFile
+                .walkTopDown()
+                .filter(File::isFile)
+                .toList()
+
+            oldGeneratedFiles.size shouldBe 3
+            oldGeneratedFiles.filter { it.path.contains("io/ethers/contracts") }.size shouldBe 2
+
+            // delete previous ABI files, and copy new ones, keeping the wrappers in build folder
+            abiDir.deleteRecursively()
+            File(EthersAbigenPlugin::class.java.getResource("/abi-alt-package")!!.toURI()).copyRecursively(abiDir, true)
+
+            // new task results are not from cache, and the old output files are deleted because inputs changed
+            val result = runner.withArguments(taskName, "--build-cache", "--info").build()
+            result.tasks.filter { it.path.endsWith(taskName) }.forEach { it.outcome shouldBe TaskOutcome.SUCCESS }
+
+            val generatedFiles = project.layout.buildDirectory.dir(customOutputDir).get().asFile
+                .walkTopDown()
+                .filter(File::isFile)
+                .toList()
+
             generatedFiles.size shouldBe 3
+            generatedFiles.filter { it.path.contains("io/ethers/moved") }.size shouldBe 2
         }
     }
 })