KT-45777: Clean up build cache tests for incremental compilation

- Clean up BuildCacheRelocationIT.testKotlinIncrementalCompilation
 - Delete BuildCacheIT.testKotlinCompileIncrementalBuildWithoutRelocation
   as it is already covered by the test in BuildCacheRelocationIT
 - Add BuildCacheRelocationIT.testKotlinIncrementalCompilation_withClasspathSnapshot
- Updated BuildCacheRelocationIT.testKotlinIncrementalCompilation_withClasspathSnapshot

build-common/src/org/jetbrains/kotlin/build/report/metrics/BuildAttribute.kt

@@ -16,6 +16,7 @@ enum class BuildAttributeKind : Serializable {
 }
 
 enum class BuildAttribute(val kind: BuildAttributeKind, val readableString: String) : Serializable {
+    CACHE_DIRECTORY_NOT_POPULATED(BuildAttributeKind.REBUILD_REASON, "Cache directory not populated"),
     NO_BUILD_HISTORY(BuildAttributeKind.REBUILD_REASON, "Build history file not found"),
     NO_ABI_SNAPSHOT(BuildAttributeKind.REBUILD_REASON, "ABI snapshot not found"),
     CLASSPATH_SNAPSHOT_NOT_FOUND(BuildAttributeKind.REBUILD_REASON, "Classpath snapshot not found"),

build-common/src/org/jetbrains/kotlin/incremental/LookupStorage.kt

@@ -288,13 +288,13 @@ data class LookupSymbol(val name: String, val scope: String) : Comparable<Lookup
 }
 
 /**
- * Wrapper of a [LookupMap] which tracks changes to the map after the initialization of this [TrackedLookupMap] instance, (unless
+ * Wrapper of a [LookupMap] which tracks changes to the map after the initialization of this [TrackedLookupMap] instance (unless
  * [trackChanges] is set to `false`).
  */
 private class TrackedLookupMap(private val lookupMap: LookupMap, private val trackChanges: Boolean) {
 
-    // Note that there may be multiple operations on the same key, and the following sets contain the *latest* differences with the original
+    // Note that there may be multiple operations on the same key, and the following sets contain the *aggregated* differences with the
-    // set of keys in the map. For example, if a key is added then removed, or vice versa, it will not be present in either set.
+    // original set of keys in the map. For example, if a key is added then removed, or vice versa, it will not be present in either set.
     val addedKeys = if (trackChanges) mutableSetOf<LookupSymbolKey>() else null
     val removedKeys = if (trackChanges) mutableSetOf<LookupSymbolKey>() else null
 

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalCompilerRunner.kt

@@ -129,7 +129,15 @@ abstract class IncrementalCompilerRunner<
                 else -> providedChangedFiles
             }
 
-            val compilationMode = sourcesToCompile(caches, changedFiles, args, messageCollector, classpathAbiSnapshot)
+            // Check whether the cache directory is populated (note that it may be deleted upon a Gradle build cache hit if the directory is
+            // marked as @LocalState in the Gradle task).
+            val cacheDirectoryNotPopulated = cacheDirectory.walk().none { it.isFile }
+
+            val compilationMode = if (cacheDirectoryNotPopulated) {
+                CompilationMode.Rebuild(BuildAttribute.CACHE_DIRECTORY_NOT_POPULATED)
+            } else {
+                sourcesToCompile(caches, changedFiles, args, messageCollector, classpathAbiSnapshot)
+            }
 
             val exitCode = when (compilationMode) {
                 is CompilationMode.Incremental -> {

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalJvmCompilerRunner.kt

@@ -256,7 +256,7 @@ class IncrementalJvmCompilerRunner(
             is NotAvailableDueToMissingClasspathSnapshot -> ChangesEither.Unknown(BuildAttribute.CLASSPATH_SNAPSHOT_NOT_FOUND)
             is NotAvailableForNonIncrementalRun -> ChangesEither.Unknown(BuildAttribute.UNKNOWN_CHANGES_IN_GRADLE_INPUTS)
             is ClasspathSnapshotDisabled -> reporter.measure(BuildTime.IC_ANALYZE_CHANGES_IN_DEPENDENCIES) {
-                val lastBuildInfo = BuildInfo.read(lastBuildInfoFile) ?: return CompilationMode.Rebuild(BuildAttribute.IC_IS_NOT_ENABLED)
+                val lastBuildInfo = BuildInfo.read(lastBuildInfoFile) ?: return CompilationMode.Rebuild(BuildAttribute.NO_BUILD_HISTORY)
                 reporter.reportVerbose { "Last Kotlin Build info -- $lastBuildInfo" }
                 val scopes = caches.lookupCache.lookupSymbols.map { it.scope.ifBlank { it.name } }.distinct()
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/AbstractKotlinAndroidGradleTests.kt

@@ -1030,8 +1030,7 @@ fun getSomething() = 10
                 .filter { it.contains("[KOTLIN] compile iteration:") }
                 .drop(1)
                 .joinToString(separator = "/n")
-            val actualSources = getCompiledKotlinSources(filteredOutput).projectRelativePaths(project)
+            assertCompiledKotlinSources(project.relativize(androidModuleKt), output = filteredOutput)
-            assertSameFiles(project.relativize(androidModuleKt), actualSources, "Compiled Kotlin files differ:\n  ")
         }
     }
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/BaseGradleIT.kt

@@ -11,26 +11,19 @@ import org.gradle.api.logging.configuration.WarningMode
 import org.gradle.tooling.GradleConnector
 import org.gradle.util.GradleVersion
 import org.intellij.lang.annotations.Language
+import org.jetbrains.kotlin.cli.common.CompilerSystemProperties.COMPILE_INCREMENTAL_WITH_ARTIFACT_TRANSFORM
 import org.jetbrains.kotlin.gradle.model.ModelContainer
 import org.jetbrains.kotlin.gradle.model.ModelFetcherBuildAction
 import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerType
 import org.jetbrains.kotlin.gradle.report.BuildReportType
-import org.jetbrains.kotlin.gradle.testbase.applyAndroidTestFixes
+import org.jetbrains.kotlin.gradle.testbase.*
-import org.jetbrains.kotlin.gradle.testbase.enableCacheRedirector
-import org.jetbrains.kotlin.gradle.testbase.extractJavaCompiledSources
-import org.jetbrains.kotlin.gradle.testbase.extractKotlinCompiledSources
-import org.jetbrains.kotlin.gradle.testbase.prettyPrintXml
-import org.jetbrains.kotlin.gradle.testbase.readAndCleanupTestResults
-import org.jetbrains.kotlin.gradle.testbase.addPluginManagementToSettings
 import org.jetbrains.kotlin.gradle.util.*
 import org.jetbrains.kotlin.gradle.util.modify
 import org.jetbrains.kotlin.konan.target.HostManager
 import org.jetbrains.kotlin.konan.target.KonanTarget
 import org.jetbrains.kotlin.test.RunnerWithMuteInDatabase
-import org.jetbrains.kotlin.test.util.trimTrailingWhitespaces
 import org.junit.After
 import org.junit.AfterClass
-import org.junit.Assert
 import org.junit.Before
 import org.junit.runner.RunWith
 import java.io.File
@@ -386,14 +379,7 @@ abstract class BaseGradleIT {
         }
     }
 
-    class CompiledProject(val project: Project, val output: String, val resultCode: Int) {
+    class CompiledProject(val project: Project, val output: String, val resultCode: Int)
-        fun getCompiledKotlinSources(output: String) =
-            extractKotlinCompiledSources(project.projectDir.toPath(), output).map { sourcePath -> sourcePath.toFile() }
-
-        val compiledJavaSources: Iterable<File> by lazy {
-            extractJavaCompiledSources(output).map { sourcePath -> sourcePath.toFile() }
-        }
-    }
 
     // Basically the same as `Project.build`, tells gradle to wait for debug on 5005 port
     // Faster to type than `project.build("-Dorg.gradle.debug=true")` or `project.build(options = defaultBuildOptions().copy(debug = true))`
@@ -593,27 +579,6 @@ abstract class BaseGradleIT {
         return map { it.canonicalFile.toRelativeString(project.projectDir) }
     }
 
-    fun CompiledProject.assertSameFiles(expected: Iterable<String>, actual: Iterable<String>, messagePrefix: String): CompiledProject {
-        val expectedSet = expected.map { it.normalizePath() }.toSortedSet().joinToString("\n")
-        val actualSet = actual.map { it.normalizePath() }.toSortedSet().joinToString("\n")
-        Assert.assertEquals(messagePrefix, expectedSet, actualSet)
-        return this
-    }
-
-    fun CompiledProject.assertContainFiles(
-        expected: Iterable<String>,
-        actual: Iterable<String>,
-        messagePrefix: String = ""
-    ): CompiledProject {
-        val expectedNormalized = expected.map(::normalizePath).toSortedSet()
-        val actualNormalized = actual.map(::normalizePath).toSortedSet()
-        assertTrue(
-            actualNormalized.containsAll(expectedNormalized),
-            messagePrefix + "expected files: ${expectedNormalized.joinToString()}\n  !in actual files: ${actualNormalized.joinToString()}"
-        )
-        return this
-    }
-
     fun CompiledProject.findTasksByPattern(pattern: String): Set<String> {
         return "task '($pattern)'".toRegex().findAll(output).mapTo(HashSet()) { it.groupValues[1] }
     }
@@ -778,13 +743,14 @@ Finished executing task ':$taskName'|
         output: String = this.output,
         suffix: String = ""
     ): CompiledProject {
-        val messagePrefix = "Compiled Kotlin files differ${suffix}:\n  "
+        val messagePrefix = "Compiled Kotlin files differ${suffix}:\n"
-        val actualSources = getCompiledKotlinSources(output).projectRelativePaths(this.project)
+        val actualSources = extractCompiledKotlinFiles(output)
-        return if (weakTesting) {
+        if (weakTesting) {
-            assertContainFiles(expectedSourcesRelativePaths, actualSources, messagePrefix)
+            assertContainsFiles(expectedSourcesRelativePaths.toPaths(), actualSources, messagePrefix)
         } else {
-            assertSameFiles(expectedSourcesRelativePaths, actualSources, messagePrefix)
+            assertSameFiles(expectedSourcesRelativePaths.toPaths(), actualSources, messagePrefix)
         }
+        return this
     }
 
     fun CompiledProject.assertCompiledKotlinFiles(expectedFiles: Iterable<File>): CompiledProject =
@@ -799,11 +765,15 @@ Finished executing task ':$taskName'|
     fun CompiledProject.assertCompiledJavaSources(
         sources: Iterable<String>,
         weakTesting: Boolean = false
-    ): CompiledProject =
+    ): CompiledProject {
+        val messagePrefix = "Compiled Java files differ:\n"
+        val actualSources = extractCompiledJavaFiles(project.projectDir, output)
         if (weakTesting)
-            assertContainFiles(sources, compiledJavaSources.projectRelativePaths(this.project), "Compiled Java files differ:\n  ")
+            assertContainsFiles(sources.toPaths(), actualSources, messagePrefix)
         else
-            assertSameFiles(sources, compiledJavaSources.projectRelativePaths(this.project), "Compiled Java files differ:\n  ")
+            assertSameFiles(sources.toPaths(), actualSources, messagePrefix)
+        return this
+    }
 
     fun Project.resourcesDir(subproject: String? = null, sourceSet: String = "main"): String =
         (subproject?.plus("/") ?: "") + "build/resources/$sourceSet/"
@@ -904,7 +874,7 @@ Finished executing task ':$taskName'|
             options.incrementalJsKlib?.let { add("-Pkotlin.incremental.js.klib=$it") }
             options.jsIrBackend?.let { add("-Pkotlin.js.useIrBackend=$it") }
             options.usePreciseJavaTracking?.let { add("-Pkotlin.incremental.usePreciseJavaTracking=$it") }
-            options.useClasspathSnapshot?.let { add("-Pkotlin.incremental.useClasspathSnapshot=$it") }
+            options.useClasspathSnapshot?.let { add("-P${COMPILE_INCREMENTAL_WITH_ARTIFACT_TRANSFORM.property}=$it") }
             options.androidGradlePluginVersion?.let { add("-Pandroid_tools_version=$it") }
             if (options.debug) {
                 add("-Dorg.gradle.debug=true")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/BuildCacheIT.kt

@@ -103,33 +103,6 @@ class BuildCacheIT : KGPBaseTest() {
         }
     }
 
-    @DisplayName("Incremental compilation works with cache")
-    @GradleTest
-    fun testKotlinCompileIncrementalBuildWithoutRelocation(gradleVersion: GradleVersion) {
-        project("buildCacheSimple", gradleVersion) {
-            enableLocalBuildCache(localBuildCacheDir)
-
-            build("assemble") {
-                assertTasksPackedToCache(":compileKotlin")
-            }
-
-            build("clean", "assemble") {
-                assertTasksFromCache(":compileKotlin")
-            }
-
-            val fooKtSourceFile = kotlinSourcesDir().resolve("foo.kt")
-            fooKtSourceFile.modify { it.replace("Int = 1", "String = \"abc\"") }
-            build("assemble") {
-                assertIncrementalCompilation(modifiedFiles = setOf(fooKtSourceFile))
-            }
-
-            fooKtSourceFile.modify { it.replace("String = \"abc\"", "Int = 1") }
-            build("clean", "assemble") {
-                assertTasksFromCache(":compileKotlin")
-            }
-        }
-    }
-
     @DisplayName("Debug log level should not break build cache")
     @GradleTest
     fun testDebugLogLevelCaching(gradleVersion: GradleVersion) {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/BuildCacheRelocationIT.kt

@@ -16,11 +16,13 @@
 
 package org.jetbrains.kotlin.gradle
 
+import org.gradle.api.logging.LogLevel
 import org.gradle.api.logging.configuration.WarningMode
 import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.DisplayName
 import kotlin.io.path.createDirectory
+import kotlin.io.path.pathString
 
 @DisplayName("Build cache relocation")
 @SimpleGradlePluginTests
@@ -260,20 +262,6 @@ class BuildCacheRelocationIT : KGPBaseTest() {
         )
     }
 
-    @DisplayName("Incremental compilation build cache does not break relocated cache")
-    @GradleTest
-    fun testKotlinCompileCachingIncrementalBuildWithRelocation(gradleVersion: GradleVersion) {
-        val firstProject = project("buildCacheSimple", gradleVersion) {
-            enableLocalBuildCache(localBuildCacheDir)
-        }
-
-        val secondProject = project("buildCacheSimple", gradleVersion) {
-            enableLocalBuildCache(localBuildCacheDir)
-        }
-
-        checkKotlinCompileCachingIncrementalBuild(firstProject, secondProject)
-    }
-
     @DisplayName("Kapt incremental compilation works with cache")
     @GradleTest
     fun testKaptCachingIncrementalBuildWithoutRelocation(gradleVersion: GradleVersion) {
@@ -332,10 +320,22 @@ class BuildCacheRelocationIT : KGPBaseTest() {
         }
     }
 
-    private fun checkKotlinCompileCachingIncrementalBuild(
+    @DisplayName("Kotlin incremental compilation should work correctly")
-        firstProject: TestProject,
+    @GradleTest
-        secondProject: TestProject
+    fun testKotlinIncrementalCompilation(gradleVersion: GradleVersion) {
-    ) {
+        checkKotlinIncrementalCompilation(gradleVersion)
+    }
+
+    @DisplayName("Kotlin incremental compilation with `kotlin.incremental.useClasspathSnapshot` feature should work correctly")
+    @GradleTest
+    fun testKotlinIncrementalCompilation_withClasspathSnapshot(gradleVersion: GradleVersion) {
+        checkKotlinIncrementalCompilation(gradleVersion, useClasspathSnapshot = true)
+    }
+
+    private fun checkKotlinIncrementalCompilation(gradleVersion: GradleVersion, useClasspathSnapshot: Boolean? = null) {
+        val buildOptions = defaultBuildOptions.copy(useClasspathSnapshot = useClasspathSnapshot)
+        val (firstProject, secondProject) = prepareTestProjects("buildCacheSimple", gradleVersion, buildOptions)
+
         // First build, should be stored into the build cache:
         firstProject.build("assemble") {
             assertTasksPackedToCache(":compileKotlin")
@@ -348,9 +348,12 @@ class BuildCacheRelocationIT : KGPBaseTest() {
 
         // Change the return type of foo() from Int to String in foo.kt, and check that fooUsage.kt is recompiled as well:
         val fooKtSourceFile = secondProject.kotlinSourcesDir().resolve("foo.kt")
+        val fooUsageKtSourceFile = secondProject.kotlinSourcesDir().resolve("fooUsage.kt")
         fooKtSourceFile.modify { it.replace("Int = 1", "String = \"abc\"") }
-        secondProject.build("assemble") {
+        secondProject.build("assemble", buildOptions = buildOptions.copy(logLevel = LogLevel.DEBUG)) {
-            assertIncrementalCompilation(modifiedFiles = setOf(fooKtSourceFile))
+            assertIncrementalCompilation(
+                listOf(fooKtSourceFile, fooUsageKtSourceFile).relativizeTo(secondProject.projectPath).map { it.pathString }
+            )
         }
 
         // Revert the change to the return type of foo(), and check if we get a cache hit

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/BuildOptions.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.gradle.testbase
 import org.gradle.api.logging.LogLevel
 import org.gradle.api.logging.configuration.WarningMode
 import org.gradle.util.GradleVersion
+import org.jetbrains.kotlin.cli.common.CompilerSystemProperties.COMPILE_INCREMENTAL_WITH_ARTIFACT_TRANSFORM
 import org.jetbrains.kotlin.gradle.BaseGradleIT
 import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerType
 import org.jetbrains.kotlin.gradle.report.BuildReportType
@@ -21,6 +22,7 @@ data class BuildOptions(
     val configurationCacheProblems: BaseGradleIT.ConfigurationCacheProblems = BaseGradleIT.ConfigurationCacheProblems.FAIL,
     val parallel: Boolean = true,
     val incremental: Boolean? = null,
+    val useClasspathSnapshot: Boolean? = null,
     val maxWorkers: Int = (Runtime.getRuntime().availableProcessors() / 4 - 1).coerceAtLeast(2),
     val fileSystemWatchEnabled: Boolean = false,
     val buildCacheEnabled: Boolean = false,
@@ -81,6 +83,8 @@ data class BuildOptions(
             arguments.add("-Pkotlin.incremental=$incremental")
         }
 
+        useClasspathSnapshot?.let { arguments.add("-P${COMPILE_INCREMENTAL_WITH_ARTIFACT_TRANSFORM.property}=$it") }
+
         if (gradleVersion >= GradleVersion.version("6.5")) {
             if (fileSystemWatchEnabled) {
                 arguments.add("--watch-fs")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/compilationAssertions.kt

@@ -5,14 +5,16 @@
 
 package org.jetbrains.kotlin.gradle.testbase
 
-import java.nio.file.Path
-import java.nio.file.Paths
-import kotlin.io.path.relativeTo
 import org.gradle.api.logging.LogLevel
 import org.gradle.testkit.runner.BuildResult
 import org.intellij.lang.annotations.Language
+import java.io.File
+import java.nio.file.Path
+import java.nio.file.Paths
 
-private val kotlinSrcRegex by lazy { Regex("\\[KOTLIN\\] compile iteration: ([^\\r\\n]*)") }
+private val kotlinSrcRegex by lazy { Regex("\\[KOTLIN] compile iteration: ([^\\r\\n]*)") }
+
+private val javaSrcRegex by lazy { Regex("\\[DEBUG] \\[[^]]*JavaCompiler] Compiler arguments: ([^\\r\\n]*)") }
 
 @Language("RegExp")
 private fun taskOutputRegex(
@@ -42,45 +44,56 @@ fun BuildResult.getOutputForTask(taskName: String): String = taskOutputRegex(tas
     ?: error("Could not find output for task $taskName")
 
 /**
- * Extracts list of compiled .kt files from task output
+ * Extracts the list of compiled .kt files from the build output.
  *
- * Note: log level of output should be set to [LogLevel.DEBUG]
+ * The returned paths are relative to the project directory.
+ *
+ * Note: Log level of output must be set to [LogLevel.DEBUG].
  */
-fun extractKotlinCompiledSources(projectDirectory: Path, output: String) =
+fun extractCompiledKotlinFiles(output: String): List<Path> {
-    kotlinSrcRegex.findAll(output)
+    return kotlinSrcRegex.findAll(output).asIterable()
-        .asIterable()
+        .flatMap { matchResult -> matchResult.groups[1]!!.value.split(", ") }
-        .flatMap { result ->
+        .toPaths()
-            result.groups[1]!!.value.split(", ")
+}
-                .map { source -> projectDirectory.resolve(source).normalize() }
-        }
-
-private val javaSrcRegex by lazy { Regex("\\[DEBUG\\] \\[[^\\]]*JavaCompiler\\] Compiler arguments: ([^\\r\\n]*)") }
 
 /**
- * Extracts list of compiled .java files from task output
+ * Extracts the list of compiled .java files from the build output.
  *
- * Note: log level of output should be set to [LogLevel.DEBUG]
+ * The returned paths are relative to the project directory.
+ *
+ * Note: Log level of output must be set to [LogLevel.DEBUG].
  */
-fun extractJavaCompiledSources(output: String): List<Path> =
+fun extractCompiledJavaFiles(projectDir: File, output: String): List<Path> {
-    javaSrcRegex.findAll(output).asIterable().flatMap {
+    return javaSrcRegex.findAll(output).asIterable()
-        it.groups[1]!!.value
+        .flatMap { matchResult -> matchResult.groups[1]!!.value.split(" ") }
-            .split(" ")
+        .filter { filePath -> filePath.endsWith(".java", ignoreCase = true) }
-            .filter { source -> source.endsWith(".java", ignoreCase = true) }
+        .map { javaFilePath -> projectDir.toPath().relativize(Paths.get(javaFilePath)) }
-            .map { source -> Paths.get(source).normalize() }
+}
-    }
 
 /**
  * Asserts all the .kt files from [expectedSources] and only they are compiled
  *
  * Note: log level of output should be set to [LogLevel.DEBUG]
  */
-fun GradleProject.assertCompiledKotlinSources(
+fun assertCompiledKotlinSources(
     expectedSources: Iterable<Path>,
     output: String,
     errorMessageSuffix: String = ""
 ) {
-    val actualSources = extractKotlinCompiledSources(projectPath, output).map {
+    val actualSources = extractCompiledKotlinFiles(output)
-        it.relativeTo(projectPath)
-    }
     assertSameFiles(expectedSources, actualSources, "Compiled Kotlin files differ${errorMessageSuffix}:\n")
 }
+
+/**
+ * Asserts that compilation was incremental and the set of compiled .kt files exactly match [expectedCompiledKotlinFiles].
+ *
+ * [expectedCompiledKotlinFiles] are relative to the project directory.
+ *
+ * Note: Log level of output must be set to [LogLevel.DEBUG].
+ */
+fun BuildResult.assertIncrementalCompilation(expectedCompiledKotlinFiles: Iterable<String>) {
+    assertOutputDoesNotContain("Non-incremental compilation will be performed")
+
+    val actualCompiledKotlinFiles = extractCompiledKotlinFiles(output)
+    assertSameFiles(expectedCompiledKotlinFiles.toPaths(), actualCompiledKotlinFiles, "Compiled Kotlin files differ:\n")
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/configurationCacheHelpers.kt

@@ -55,7 +55,7 @@ fun TestProject.assertSimpleConfigurationCacheScenarioWorks(
  */
 @OptIn(ExperimentalPathApi::class)
 private fun copyReportToTempDir(htmlReportFile: Path): Path =
-    createTempDir("report").let { tempDir ->
+    createTempDirDeleteOnExit("report").let { tempDir ->
         htmlReportFile.parent.toFile().copyRecursively(tempDir.toFile())
         tempDir.resolve(htmlReportFile.name)
     }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/fileAssertions.kt

@@ -10,7 +10,7 @@ import java.nio.file.Path
 import kotlin.io.path.exists
 import kotlin.io.path.isDirectory
 import kotlin.io.path.readText
-import kotlin.test.assertEquals
+import kotlin.test.asserter
 
 /**
  * Asserts file under [file] path exists and is a regular file.
@@ -189,8 +189,24 @@ fun GradleProject.assertFileDoesNotContain(
     }
 }
 
-fun GradleProject.assertSameFiles(expected: Iterable<Path>, actual: Iterable<Path>, messagePrefix: String) {
+fun assertSameFiles(expected: Iterable<Path>, actual: Iterable<Path>, messagePrefix: String) {
-    val expectedSet = expected.map { it.toString().normalizePath() }.toSortedSet().joinToString("\n")
+    val expectedSet = expected.map { it.toString().normalizePath() }.toSet()
-    val actualSet = actual.map { it.toString().normalizePath() }.toSortedSet().joinToString("\n")
+    val actualSet = actual.map { it.toString().normalizePath() }.toSet()
-    assertEquals(expectedSet, actualSet, messagePrefix)
+    asserter.assertTrue(lazyMessage = {
+        messagePrefix +
+                "Actual set does not exactly match expected set.\n" +
+                "Expected set: ${expectedSet.sorted().joinToString(", ")}\n" +
+                "Actual set: ${actualSet.sorted().joinToString(", ")}\n"
+    }, actualSet.size == expectedSet.size && actualSet.containsAll(expectedSet))
+}
+
+fun assertContainsFiles(expected: Iterable<Path>, actual: Iterable<Path>, messagePrefix: String) {
+    val expectedSet = expected.map { it.toString().normalizePath() }.toSet()
+    val actualSet = actual.map { it.toString().normalizePath() }.toSet()
+    asserter.assertTrue(lazyMessage = {
+        messagePrefix +
+                "Actual set does not contain all of expected set.\n" +
+                "Expected set: ${expectedSet.sorted().joinToString(", ")}\n" +
+                "Actual set: ${actualSet.sorted().joinToString(", ")}\n"
+    }, actualSet.containsAll(expectedSet))
 }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/outputAssertions.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.gradle.testbase
 
 import org.gradle.testkit.runner.BuildResult
-import java.nio.file.Path
 
 /**
  * Asserts Gradle output contains [expectedSubString] string.
@@ -127,70 +126,6 @@ fun BuildResult.assertNoBuildWarnings(
     }
 }
 
-fun BuildResult.assertIncrementalCompilation(
-    modifiedFiles: Set<Path> = emptySet(),
-    deletedFiles: Set<Path> = emptySet()
-) {
-    val incrementalCompilationOptions = output
-        .lineSequence()
-        .filter { it.trim().startsWith("Options for KOTLIN DAEMON: IncrementalCompilationOptions(") }
-        .map {
-            it
-                .removePrefix("Options for KOTLIN DAEMON: IncrementalCompilationOptions(")
-                .removeSuffix(")")
-        }
-        .toList()
-
-    assert(incrementalCompilationOptions.isNotEmpty()) {
-        printBuildOutput()
-        "No incremental compilation options were found in the build"
-    }
-
-    val modifiedFilesPath = modifiedFiles.map { it.toAbsolutePath().toString() }
-    val deletedFilesPath = deletedFiles.map { it.toAbsolutePath().toString() }
-    val hasMatch = incrementalCompilationOptions
-        .firstOrNull {
-            val optionModifiedFiles = it
-                .substringAfter("modifiedFiles=[")
-                .substringBefore("]")
-                .split(",")
-                .filter(String::isNotEmpty)
-
-            val modifiedFilesFound = if (modifiedFilesPath.isEmpty()) {
-                optionModifiedFiles.isEmpty()
-            } else {
-                modifiedFilesPath.subtract(optionModifiedFiles).isEmpty()
-            }
-
-            val optionDeletedFiles = it
-                .substringAfter("deletedFiles=[")
-                .substringBefore("]")
-                .split(",")
-                .filter(String::isNotEmpty)
-
-            val deletedFilesFound = if (deletedFilesPath.isEmpty()) {
-                optionDeletedFiles.isEmpty()
-            } else {
-                deletedFilesPath.subtract(optionDeletedFiles).isEmpty()
-            }
-
-            modifiedFilesFound && deletedFilesFound
-        } != null
-
-    assert(hasMatch) {
-        printBuildOutput()
-
-        """
-        |Expected incremental compilation options with:
-        |- modified files: ${modifiedFilesPath.joinToString()}
-        |- deleted files: ${deletedFilesPath.joinToString()}
-        |        
-        |but none of following compilation options match:
-        |${incrementalCompilationOptions.joinToString(separator = "\n")}
-        """.trimMargin()
-    }
-}
-
 /**
  * Asserts compilation is running via Kotlin daemon with given jvm arguments.
  */

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/pathHelpers.kt

@@ -6,10 +6,7 @@
 package org.jetbrains.kotlin.gradle.testbase
 
 import java.io.IOException
-import java.nio.file.FileVisitResult
+import java.nio.file.*
-import java.nio.file.Files
-import java.nio.file.Path
-import java.nio.file.SimpleFileVisitor
 import java.nio.file.attribute.BasicFileAttributes
 import kotlin.io.path.*
 import kotlin.streams.asSequence
@@ -50,7 +47,7 @@ internal val Path.allJavaSources: List<Path>
  *
  * Prefer using JUnit5 `@TempDir` over this method when possible.
  */
-internal fun createTempDir(prefix: String): Path = Files
+internal fun createTempDirDeleteOnExit(prefix: String): Path = Files
     .createTempDirectory(prefix)
     .apply { toFile().deleteOnExit() }
 
@@ -108,3 +105,5 @@ internal fun Path.deleteRecursively() {
         }
     })
 }
+
+internal fun Iterable<String>.toPaths(): List<Path> = map { Paths.get(it) }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/util/fileUtil.kt

@@ -5,10 +5,8 @@
 
 package org.jetbrains.kotlin.gradle.util
 
+import org.jetbrains.kotlin.gradle.testbase.createTempDirDeleteOnExit
 import java.io.File
-import java.nio.file.Files
-import java.nio.file.Path
-import kotlin.io.path.relativeTo
 
 fun File.getFileByName(name: String): File =
     findFileByName(name) ?: throw AssertionError("Could not find file with name '$name' in $this")
@@ -36,10 +34,7 @@ fun File.addNewLine() {
     modify { "$it\n" }
 }
 
-fun createTempDir(prefix: String): File =
+fun createTempDir(prefix: String): File = createTempDirDeleteOnExit(prefix).toFile()
-    Files.createTempDirectory(prefix).toFile().apply {
-        deleteOnExit()
-    }
 
 /**
  * converts back slashes to forward slashes

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/buildCacheSimple/src/main/kotlin/StandAloneClass.kt

@@ -0,0 +1,3 @@
+// This class is used so that the set of compiled source files in an incremental compilation is a proper subset of the set of compiled
+// source files in a non-incremental compilation, so that the two cases are not ambiguous when we check the set of compiled source files.
+class StandAloneClass