Add version file to each module resources (Kotlin#2950)

* Add version file to each module resources
* The approach with "Specification-Version" in Manifest doesn't work because Android merges all JARs into a single resource, trimming all the manifests

Fixes Kotlin#2941

build.gradle

@@ -233,6 +233,40 @@ configure(subprojects.findAll { !unpublished.contains(it.name) }) {
             }
         }
     }
+
+    def thisProject = it
+    if (thisProject.name in sourceless) {
+        return
+    }
+
+    def versionFileTask = thisProject.tasks.register("versionFileTask") {
+        def name = thisProject.name.replace("-", "_")
+        def versionFile = thisProject.layout.buildDirectory.file("${name}.version")
+        it.outputs.file(versionFile)
+
+        it.doLast {
+            versionFile.get().asFile.text = version.toString()
+        }
+    }
+
+    List<String> jarTasks
+    if (it.name == "kotlinx-coroutines-core") {
+        jarTasks = ["jvmJar", "metadataJar"]
+    } else if (it.name == "kotlinx-coroutines-debug") {
+        // We shadow debug module instead of just packaging it
+        jarTasks = ["shadowJar"]
+    } else {
+        jarTasks = ["jar"]
+    }
+
+    for (name in jarTasks) {
+        thisProject.tasks.named(name, Jar) {
+            it.dependsOn versionFileTask
+            it.from(versionFileTask) {
+                into("META-INF")
+            }
+        }
+    }
 }
 
 // Report Kotlin compiler version when building project

integration-testing/build.gradle

@@ -58,6 +58,7 @@ task npmTest(type: Test) {
 }
 
 task mavenTest(type: Test) {
+    environment "version", version
     def sourceSet = sourceSets.mavenTest
     dependsOn(project(':').getTasksByName("publishToMavenLocal", true))
     testClassesDirs = sourceSet.output.classesDirs

integration-testing/src/mavenTest/kotlin/MavenPublicationValidator.kt → integration-testing/src/mavenTest/kotlin/MavenPublicationAtomicfuValidator.kt

@@ -8,7 +8,7 @@ import org.junit.*
 import org.junit.Assert.assertTrue
 import java.util.jar.*
 
-class MavenPublicationValidator {
+class MavenPublicationAtomicfuValidator {
     private val ATOMIC_FU_REF = "Lkotlinx/atomicfu/".toByteArray()
 
     @Test

integration-testing/src/mavenTest/kotlin/MavenPublicationVersionValidator.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.coroutines.validator
+
+import org.junit.*
+import org.junit.Test
+import java.util.jar.*
+import kotlin.test.*
+
+class MavenPublicationVersionValidator {
+
+    @Test
+    fun testMppJar() {
+        val clazz = Class.forName("kotlinx.coroutines.Job")
+        JarFile(clazz.protectionDomain.codeSource.location.file).checkForVersion("kotlinx_coroutines_core.version")
+    }
+
+    @Test
+    fun testAndroidJar() {
+        val clazz = Class.forName("kotlinx.coroutines.android.HandlerDispatcher")
+        JarFile(clazz.protectionDomain.codeSource.location.file).checkForVersion("kotlinx_coroutines_android.version")
+    }
+
+    private fun JarFile.checkForVersion(file: String) {
+        val actualFile = "META-INF/$file"
+        val version = System.getenv("version")
+        use {
+            for (e in entries()) {
+                if (e.name == actualFile) {
+                    val string = getInputStream(e).readAllBytes().decodeToString()
+                    assertEquals(version, string)
+                    return
+                }
+            }
+            error("File $file not found")
+        }
+    }
+}