Fix missing PsiTreeChangeListener

Author: tschuchortdev

build.gradle

@@ -1,9 +1,8 @@
 buildscript {
-    ext.kotlin_version = '1.5.10'
+    ext.kotlin_version = '1.5.21'
 
     repositories {
         mavenCentral()
-        jcenter()
         maven { url "https://plugins.gradle.org/m2/" }
         maven { url 'https://dl.bintray.com/kotlin/kotlin-eap' }
         google()
@@ -41,7 +40,6 @@ allprojects {
     buildscript {
         repositories {
             mavenCentral()
-            jcenter()
             maven { url 'https://dl.bintray.com/kotlin/kotlin-eap' }
             maven { url "https://plugins.gradle.org/m2/" }
             google()

ksp/src/main/kotlin/com/tschuchort/compiletesting/Ksp.kt

@@ -12,7 +12,10 @@ import org.jetbrains.kotlin.cli.common.CLIConfigurationKeys
 import org.jetbrains.kotlin.cli.common.messages.MessageRenderer
 import org.jetbrains.kotlin.cli.common.messages.PrintingMessageCollector
 import org.jetbrains.kotlin.cli.jvm.config.JavaSourceRoot
+import org.jetbrains.kotlin.com.intellij.core.CoreApplicationEnvironment
 import org.jetbrains.kotlin.com.intellij.mock.MockProject
+import org.jetbrains.kotlin.com.intellij.psi.PsiTreeChangeAdapter
+import org.jetbrains.kotlin.com.intellij.psi.PsiTreeChangeListener
 import org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.resolve.jvm.extensions.AnalysisHandlerExtension
@@ -182,6 +185,8 @@ private class KspCompileTestingComponentRegistrar(
         )
         val registrar = KspTestExtension(options, providers, messageCollectorBasedKSPLogger)
         AnalysisHandlerExtension.registerExtension(project, registrar)
+        // Dummy extension point; Required by dropPsiCaches().
+        CoreApplicationEnvironment.registerExtensionPoint(project.extensionArea, PsiTreeChangeListener.EP.name, PsiTreeChangeAdapter::class.java)
     }
 }