[KPM] kotlin-gradle-plugin-idea: Use special publication for backwards compatibility tests

KT-51386

gradle/verification-metadata.xml

@@ -20,6 +20,7 @@
          <trust group="org.jetbrains.kotlin" name="kotlin-gradle-plugin-api"/>
          <trust group="org.jetbrains.kotlin" name="kotlin-gradle-plugin-model"/>
          <trust group="org.jetbrains.kotlin" name="kotlin-gradle-plugin-idea"/>
+         <trust group="org.jetbrains.kotlin" name="kotlin-gradle-plugin-idea-for-compatibility-tests"/>
          <trust group="org.jetbrains.kotlin" name="kotlin-klib-commonizer-api"/>
          <trust group="org.jetbrains.kotlin" name="kotlin-klib-commonizer-embeddable"/>
          <trust group="org.jetbrains.kotlin" name="kotlin-tooling-metadata"/>

libraries/tools/kotlin-gradle-plugin-idea/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     kotlin("jvm")
     `java-test-fixtures`
+    `maven-publish`
 }
 
 object BackwardsCompatibilityTestConfiguration {
@@ -29,10 +30,28 @@ dependencies {
     testFixturesImplementation(project(":kotlin-test:kotlin-test-junit"))
 }
 
+repositories {
+    mavenLocal()
+}
+
 publish()
 javadocJar()
 sourcesJar()
 
+//region Setup: Backwards compatibility tests
+
+/*
+A special publication is necessary for later downloading such artifact from within this module.
+If we wanted to download a publication with the same coordinates, Gradle would always rewrite
+the dependency to a local project dependency (knowing, that the coodriantes belong to this project)
+ */
+publishing {
+    publications.create<MavenPublication>("for-compatibility-tests") {
+        artifactId = "kotlin-gradle-plugin-idea-for-compatibility-tests"
+        artifact(tasks.named("jar"))
+    }
+}
+
 /* Setup Backwards Compatibility Test */
 run {
     /* When -Pkgp-idea-snapshot is set, then the test runs against a locally installed snapshot version (./gradlew install) */
@@ -48,23 +67,31 @@ run {
     val minimalBackwardsCompatibleVersionTestClasspath by configurations.creating {
         isCanBeResolved = true
         isCanBeConsumed = false
-        attributes {
-            attribute(Usage.USAGE_ATTRIBUTE, objects.named(Usage.JAVA_RUNTIME))
-        }
     }
 
     dependencies {
-        minimalBackwardsCompatibleVersionTestClasspath("org.jetbrains.kotlin:kotlin-gradle-plugin-idea:$version")
+        minimalBackwardsCompatibleVersionTestClasspath(
+            "org.jetbrains.kotlin:kotlin-gradle-plugin-idea-for-compatibility-tests:$version"
+        )
+
+        minimalBackwardsCompatibleVersionTestClasspath(
+            "org.jetbrains.kotlin:kotlin-stdlib:$version"
+        )
     }
 
     tasks.test {
+        dependsOnKotlinGradlePluginInstall()
         inputs.files(minimalBackwardsCompatibleVersionTestClasspath)
         doFirst {
             if (isSnapshotTest) logger.quiet("Running test against snapshot: $version")
             else logger.quiet("Running test against $version")
 
+            /*
+             Perform a check on the resolved classpath to ensure, that indeed the requested version is resolved.
+             This is a last line of defense against some unexpected Gradle resolution (like back resolving to this original project)
+             */
             val resolvedClasspath = minimalBackwardsCompatibleVersionTestClasspath.files
-            if (resolvedClasspath.none { "kotlin-gradle-plugin-idea-$version.jar" in it.path }) {
+            if (resolvedClasspath.none { "kotlin-gradle-plugin-idea-for-compatibility-tests-$version.jar" in it.path }) {
                 throw IllegalStateException(buildString {
                     appendLine("Bad backwardsCompatibilityClasspath: $resolvedClasspath")
                     appendLine("Dependencies:${minimalBackwardsCompatibleVersionTestClasspath.allDependencies.joinToString()}")
@@ -78,3 +105,5 @@ run {
         }
     }
 }
+
+//endregion