AndroidLibrarySupport: Add Java Android library support

Fixes: #94

src/functionalTest/kotlin/kotlinx/validation/api/TestDsl.kt

@@ -47,6 +47,18 @@ internal fun FileContainer.kotlin(classFileName: String, sourceSet:String = "mai
     file(fileName, fn)
 }
 
+/**
+ * same as [file][FileContainer.file], but prepends "src/${sourceSet}/java" before given `classFileName`
+ */
+internal fun FileContainer.java(classFileName: String, sourceSet:String = "main", fn: AppendableScope.() -> Unit) {
+    require(classFileName.endsWith(".java")) {
+        "ClassFileName must end with '.java'"
+    }
+
+    val fileName = "src/${sourceSet}/java/$classFileName"
+    file(fileName, fn)
+}
+
 /**
  * Shortcut for creating a `build.gradle.kts` by using [file][FileContainer.file]
  */

src/functionalTest/kotlin/kotlinx/validation/test/AndroidLibraryTest.kt

@@ -44,7 +44,32 @@ internal class AndroidLibraryTest : BaseKotlinGradleTest() {
 
     //region Java Android Library
 
-    // TODO #94 Java Android Library functional test cases
+    @Test
+    fun `Given a Java Android Library, when api is dumped, then task should be successful`() {
+        val runner = test {
+            createProjectWithSubModules()
+            runner {
+                arguments.add(":java-library:apiDump")
+                arguments.add("--full-stacktrace")
+            }
+        }
+
+        runner.build().apply {
+            assertTaskSuccess(":java-library:apiDump")
+        }
+    }
+
+    @Test
+    fun `Given a Java Android Library, when api is checked, then it should match the expected`() {
+        test {
+            createProjectWithSubModules()
+            runner {
+                arguments.add(":java-library:apiCheck")
+            }
+        }.build().apply {
+            assertTaskSuccess(":java-library:apiCheck")
+        }
+    }
 
     //endregion
 
@@ -76,7 +101,12 @@ internal class AndroidLibraryTest : BaseKotlinGradleTest() {
             buildGradleKts {
                 resolve("examples/gradle/base/androidJavaLibrary.gradle.kts")
             }
-            // TODO #94 Add sample Java class and expected api dump file
+            java("JavaLib.java") {
+                resolve("examples/classes/JavaLib.java")
+            }
+            apiFile(projectName = "java-library") {
+                resolve("examples/classes/JavaLib.dump")
+            }
         }
     }
 

src/functionalTest/resources/examples/classes/JavaLib.dump

@@ -0,0 +1,12 @@
+public final class examples/classes/JavaLib {
+	public fun <init> ()V
+	public fun foo ()Ljava/lang/String;
+}
+
+public final class org/jetbrains/kotlinx/android/java/library/BuildConfig {
+	public static final field BUILD_TYPE Ljava/lang/String;
+	public static final field DEBUG Z
+	public static final field LIBRARY_PACKAGE_NAME Ljava/lang/String;
+	public fun <init> ()V
+}
+

src/functionalTest/resources/examples/classes/JavaLib.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2016-2022 JetBrains s.r.o.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package examples.classes;
+
+public final class JavaLib {
+
+  public String foo() {
+    return "foo";
+  }
+
+  private String bar() {
+    return "bar";
+  }
+
+}

src/main/kotlin/BinaryCompatibilityValidatorPlugin.kt

@@ -5,10 +5,12 @@
 
 package kotlinx.validation
 
+import com.android.build.gradle.LibraryExtension
 import org.gradle.api.*
 import org.gradle.api.plugins.*
 import org.gradle.api.provider.*
 import org.gradle.api.tasks.*
+import org.gradle.api.tasks.compile.JavaCompile
 import org.jetbrains.kotlin.gradle.dsl.*
 import org.jetbrains.kotlin.gradle.plugin.*
 import java.io.*
@@ -108,15 +110,43 @@ class BinaryCompatibilityValidatorPlugin : Plugin<Project> {
     private fun configureAndroidPlugin(
         project: Project,
         extension: ApiValidationExtension
+    ) {
+        val kotlinPluginPresent = project.plugins
+            .withType(KotlinAndroidPluginWrapper::class.java)
+            .isEmpty().not()
+
+        if (kotlinPluginPresent) {
+            configureAndroidPluginForKotlinLibrary(project, extension)
+        } else {
+            configureAndroidPluginForJavaLibrary(project, extension)
+        }
+    }
+
+    private fun configureAndroidPluginForKotlinLibrary(
+        project: Project,
+        extension: ApiValidationExtension
     ) = configurePlugin("kotlin-android", project, extension) {
-        val androidExtension = project.extensions.getByName("kotlin") as KotlinAndroidProjectExtension
+        val androidExtension = project.extensions
+            .getByName("kotlin") as KotlinAndroidProjectExtension
         androidExtension.target.compilations.matching {
             it.compilationName == "release"
         }.all {
             project.configureKotlinCompilation(it, extension, useOutput = true)
         }
     }
 
+    private fun configureAndroidPluginForJavaLibrary(
+        project: Project,
+        extension: ApiValidationExtension
+    ) = configurePlugin("com.android.library", project, extension) {
+        val androidExtension = project.extensions.getByType(LibraryExtension::class.java)
+        androidExtension.libraryVariants.matching {
+            it.name == "release"
+        }.all {
+            project.configureJavaCompilation(it.javaCompileProvider, extension)
+        }
+    }
+
     private fun configureKotlinPlugin(
         project: Project,
         extension: ApiValidationExtension
@@ -212,6 +242,39 @@ internal val Project.apiValidationExtensionOrNull: ApiValidationExtension?
             .map { it.extensions.findByType(ApiValidationExtension::class.java) }
             .firstOrNull { it != null }
 
+private fun Project.configureJavaCompilation(
+    configurableFileCollection: TaskProvider<JavaCompile>,
+    extension: ApiValidationExtension,
+    targetConfig: TargetConfig = TargetConfig(this),
+) {
+    val projectName = project.name
+    val apiDirProvider = targetConfig.apiDir
+    val apiBuildDir = apiDirProvider.map { buildDir.resolve(it) }
+
+    val apiBuild = task<KotlinApiBuildTask>(targetConfig.apiTaskName("Build"), extension) {
+        isEnabled = apiCheckEnabled(projectName, extension)
+        // 'group' is not specified deliberately, so it will be hidden from ./gradlew tasks
+        description = "Builds Java API for 'main' compilations of $projectName. " +
+                "Complementary task and shouldn't be called manually"
+        inputClassesDirs = files(provider<Any> {
+            if (isEnabled) configurableFileCollection.get().outputs.files
+            else emptyList<Any>()
+        })
+        inputDependencies = files(provider<Any> {
+            if (isEnabled) configurableFileCollection.get().outputs.files
+            else emptyList<Any>()
+        })
+        outputApiDir = apiBuildDir.get()
+    }
+
+    configureCheckTasks(
+        apiBuildDir,
+        apiBuild,
+        extension,
+        targetConfig
+    )
+}
+
 fun apiCheckEnabled(projectName: String, extension: ApiValidationExtension): Boolean =
     projectName !in extension.ignoredProjects && !extension.validationDisabled