`NoClassDefFoundError` on test running after new class creation

[Undin]

Describe the bug
After updating to gradle-intellij-plugin 1.6.0, I constantly faced with NoClassDefFoundError exception on test running after new class creation (including creation new lambda since it creates new anonymous class from JVM point of view).
1.7.0-SNAPSHOT version doesn't help so master doesn't contain the corresponding fix.

Using 1.5.3 version helps, but it breaks launching plugin with 2022.2 IDEs.
Test running after clean task helps as well, but it's too slow since it recompiles everything from scratch

I assume it's because of using com.intellij.util.lang.PathClassLoader as system classloader added to 1.6.0

Stacktrace example

com/jetbrains/edu/learning/EduDocumentListenerTest$test type in placeholder$r$1
java.lang.NoClassDefFoundError: com/jetbrains/edu/learning/EduDocumentListenerTest$test type in placeholder$r$1
	at com.jetbrains.edu.learning.EduDocumentListenerTest.test type in placeholder(EduDocumentListenerTest.kt:23)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at junit.framework.TestCase.runTest(TestCase.java:176)
	at com.intellij.testFramework.UsefulTestCase.lambda$runBare$11(UsefulTestCase.java:533)
	at com.intellij.testFramework.UsefulTestCase.lambda$wrapTestRunnable$13(UsefulTestCase.java:554)
	at com.intellij.testFramework.UsefulTestCase.runTestRunnable(UsefulTestCase.java:454)
	at com.intellij.testFramework.fixtures.BasePlatformTestCase.runTestRunnable(BasePlatformTestCase.java:106)
	at com.intellij.testFramework.UsefulTestCase.defaultRunBare(UsefulTestCase.java:470)
	at com.intellij.testFramework.UsefulTestCase.lambda$runBare$12(UsefulTestCase.java:541)
	at com.intellij.testFramework.EdtTestUtil.lambda$runInEdtAndWait$1(EdtTestUtil.java:40)
	at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:303)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:770)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:740)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:393)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Caused by: java.lang.ClassNotFoundException: com.jetbrains.edu.learning.EduDocumentListenerTest$test type in placeholder$r$1
	at com.intellij.util.lang.UrlClassLoader.findClass(UrlClassLoader.java:215)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
	... 27 more

To Reproduce

• checkout arseniy/classloading-problem branch of EduTools plugin
• run gradle clean
• run com.jetbrains.edu.learning.EduDocumentListenerTest#test type in placeholder test. It should pass
• uncomment these lines
• run com.jetbrains.edu.learning.EduDocumentListenerTest#test type in placeholder test again

Expected behavior
Test passes without NoClassDefFoundError

Environment:

• OS: macOS 12.3.1
• Gradle IntelliJ Plugin Version: 1.7.0-SNAPSHOT
• Gradle Version: 7.4

[nico-loeber]

I've got the same issue. I wasn't aware this is caused by the gradle-intellij-plugin.

[hsz]

The problem is caused because of the new PathClassLoader introduced for 221+.
When running the instrumentation, by default the classpath.index file is created next to the instrumented classes, however, it doesn't get updated with an incremental run. The previous classloader provided an option for disabling the creation of this file entirely, but now it's not possible.
As a workaround, I'm removing such a file every time the instrumentation task runs, so it gets recreated.

[hsz]

Fix is available in the latest snapshot.