fix(bgp): package local jars of embedded libraries into the AAR

.changeset/aar-local-jars.md

@@ -0,0 +1,5 @@
+---
+'@callstack/react-native-brownfield': patch
+---
+
+fix: package classes from libraries' local jars (`libs/*.jar`) into the Android AAR; previously host apps crashed with NoClassDefFoundError. If your app also has those classes, because it added the jar itself as a workaround or depends on a library that the jar bundles, the build now fails with duplicate classes: remove the app's copy

apps/RNApp/android/build.gradle

@@ -16,7 +16,7 @@ buildscript {
         classpath("com.android.tools.build:gradle")
         classpath("com.facebook.react:react-native-gradle-plugin")
         classpath("org.jetbrains.kotlin:kotlin-gradle-plugin")
-        classpath("com.callstack.react:brownfield-gradle-plugin:2.0.0-alpha11-SNAPSHOT")
+        classpath("com.callstack.react:brownfield-gradle-plugin:2.0.0-alpha12-SNAPSHOT")
     }
 }
 

apps/scripts/prepare-android-build-gradle-for-ci.ts

@@ -9,7 +9,7 @@ if (!projectDirName) {
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
-const SNAPSHOT_VERSION = '2.0.0-alpha11-SNAPSHOT';
+const SNAPSHOT_VERSION = '2.0.0-alpha12-SNAPSHOT';
 // Accepts a repo-relative app dir (e.g. "ExpoApp58") or an absolute path (e.g.
 // the scaffold-smoke app created outside the repo).
 const projectDir = path.isAbsolute(projectDirName)

gradle-plugins/react/brownfield/gradle.properties

@@ -1,6 +1,6 @@
 PROJECT_ID=com.callstack.react.brownfield
 ARTIFACT_ID=brownfield-gradle-plugin
-VERSION=2.0.0-alpha11
+VERSION=2.0.0-alpha12
 GROUP=com.callstack.react
 IMPLEMENTATION_CLASS=com.callstack.react.brownfield.plugin.RNBrownfieldPlugin
 

gradle-plugins/react/brownfield/src/main/kotlin/com/callstack/react/brownfield/processors/VariantTaskProvider.kt

@@ -66,6 +66,10 @@ class VariantTaskProvider(val project: Project) {
             it.dependsOn(VariantHelper.getJavaCompileTask(project, capitalizedVariantName))
             it.variantName.set(variantName)
             it.inputClassesJars.from(aarLibraries.map { aarLibrary -> aarLibrary.getClassesJarFile() })
+            // libs/*.jar of each library (#489)
+            it.inputClassesJars.from(
+                aarLibraries.map { aarLibrary -> project.fileTree(aarLibrary.getLibsDir()) { tree -> tree.include("*.jar") } },
+            )
             it.outputDir.set(DirectoryManager.getMergeClassDirectory(variantName))
         }
     }

gradle-plugins/react/brownfield/src/main/kotlin/com/callstack/react/brownfield/shared/MergeClassesTask.kt

@@ -54,6 +54,8 @@ abstract class MergeClassesTask : DefaultTask() {
             copyTask.from(mergedOutputDir)
             copyTask.into(javacDir)
             copyTask.exclude("META-INF/")
+            // Root module descriptor of a library's local jar, not a class of the AAR.
+            copyTask.exclude("module-info.class")
         }
 
         project.copy { copyTask ->

gradle-plugins/react/brownfield/src/test/kotlin/com/callstack/react/brownfield/processors/MergeClassesLocalJarsTest.kt

@@ -0,0 +1,73 @@
+package com.callstack.react.brownfield.processors
+
+import com.callstack.react.brownfield.shared.ExplodeAarTask
+import com.callstack.react.brownfield.shared.UnresolvedArtifactInfo
+import com.callstack.react.brownfield.utils.AndroidArchiveLibrary
+import com.callstack.react.brownfield.utils.DirectoryManager
+import org.gradle.testfixtures.ProjectBuilder
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.io.TempDir
+import java.io.File
+import java.util.zip.ZipEntry
+import java.util.zip.ZipOutputStream
+import kotlin.test.assertTrue
+
+/**
+ * A library that ships `implementation files("libs/some.jar")` has that jar in its exploded AAR's
+ * `libs/`. Its classes must be merged with the library's own `classes.jar` (#489).
+ */
+class MergeClassesLocalJarsTest {
+    @TempDir
+    lateinit var tempDir: File
+
+    @Test
+    fun `merges classes from a library's local jars`() {
+        val project = ProjectBuilder.builder().withProjectDir(tempDir).build()
+        DirectoryManager.project = project
+
+        val variantName = "release"
+        val library =
+            AndroidArchiveLibrary(
+                project,
+                UnresolvedArtifactInfo("RNApp", "react-native-aar-repro", "unspecified", null, false),
+                variantName,
+            )
+        val explodeTask = project.tasks.register("explodeTest", ExplodeAarTask::class.java)
+        val mergeTask = VariantTaskProvider(project).mergeClasses(listOf(library), explodeTask, variantName).get()
+
+        // Exploded after the task is configured, as on a clean build.
+        library.getExplodedAarRootDir().mkdirs()
+        writeJar(library.getClassesJarFile(), "com/aarrepro/AarReproPackage.class")
+        writeJar(
+            File(library.getLibsDir(), "aar-repro.jar"),
+            "com/aarrepro/jar/AarReproJarClass.class",
+            "module-info.class",
+        )
+
+        mergeTask.run()
+
+        val merged = mergeTask.outputDir.get().asFile
+        assertTrue(File(merged, "com/aarrepro/AarReproPackage.class").exists(), "classes.jar was not merged")
+        assertTrue(
+            File(merged, "com/aarrepro/jar/AarReproJarClass.class").exists(),
+            "classes from libs/aar-repro.jar were not merged",
+        )
+        val javacDir = File(tempDir, "build/intermediates/javac/release/compileReleaseJavaWithJavac/classes")
+        assertTrue(File(javacDir, "com/aarrepro/jar/AarReproJarClass.class").exists(), "jar classes are not compiled into the AAR")
+        assertTrue(!File(javacDir, "module-info.class").exists(), "a jar's module-info.class ended up in the AAR")
+    }
+
+    private fun writeJar(
+        jar: File,
+        vararg entries: String,
+    ) {
+        jar.parentFile.mkdirs()
+        ZipOutputStream(jar.outputStream()).use { zip ->
+            entries.forEach { entry ->
+                zip.putNextEntry(ZipEntry(entry))
+                zip.write(byteArrayOf(0xCA.toByte(), 0xFE.toByte(), 0xBA.toByte(), 0xBE.toByte()))
+                zip.closeEntry()
+            }
+        }
+    }
+}

packages/react-native-brownfield/src/expo-config-plugin/android/__tests__/gradleHelpers.test.ts

@@ -16,7 +16,7 @@ describe('gradleHelpers', () => {
 }`;
 
     expect(modifyRootBuildGradle(contents)).toContain(
-      'classpath("com.callstack.react:brownfield-gradle-plugin:2.0.0-alpha11")'
+      'classpath("com.callstack.react:brownfield-gradle-plugin:2.0.0-alpha12")'
     );
   });
 

packages/react-native-brownfield/src/expo-config-plugin/android/utils/constants.ts

@@ -1,2 +1,2 @@
-export const BROWNFIELD_PLUGIN_VERSION = '2.0.0-alpha11';
+export const BROWNFIELD_PLUGIN_VERSION = '2.0.0-alpha12';
 export const brownfieldGradlePluginDependency = `classpath("com.callstack.react:brownfield-gradle-plugin:${BROWNFIELD_PLUGIN_VERSION}")`;