KT-34862: Clean up tests for incremental compilation after cache hit

Make sure that:
  - Compilation with -Pkotlin.incremental.useClasspathSnapshot=true or
    -Dkotlin.incremental.classpath.snapshot.enabled=true is incremental
    after cache hit.
  - Default compilation (using build history files) is non-incremental
    after cache hit.

Also unify the related tests into
BuildCacheRelocationIT.testKotlinIncrementalCompilation*. We don't need
corresponding tests in BuildCacheIT because BuildCacheRelocationIT
already covers it.

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

@@ -37,19 +37,15 @@ data class BuildInfo(val startTS: Long, val dependencyToAbiSnapshot: Map<String,
         private fun ObjectOutputStream.writeBuildInfo(buildInfo: BuildInfo) {
             writeLong(buildInfo.startTS)
             writeInt(buildInfo.dependencyToAbiSnapshot.size)
-            for((identifier, abiSnapshot) in buildInfo.dependencyToAbiSnapshot) {
+            for ((identifier, abiSnapshot) in buildInfo.dependencyToAbiSnapshot) {
                 writeUTF(identifier)
                 writeAbiSnapshot(abiSnapshot)
             }
         }
 
-        fun read(file: File): BuildInfo? =
-            try {
-                ObjectInputStream(FileInputStream(file)).use {
-                    it.readBuildInfo()
-                }
-            } catch (e: Exception) {
-                null
+        fun read(file: File): BuildInfo =
+            ObjectInputStream(FileInputStream(file)).use {
+                it.readBuildInfo()
             }
 
         fun write(buildInfo: BuildInfo, file: File) {

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

@@ -46,7 +46,7 @@ abstract class IncrementalCompilerRunner<
     private val workingDir: File,
     cacheDirName: String,
     protected val reporter: BuildReporter,
-    private val buildHistoryFile: File,
+    protected val buildHistoryFile: File,
     // there might be some additional output directories (e.g. for generated java in kapt)
     // to remove them correctly on rebuild, we pass them as additional argument
     private val additionalOutputFiles: Collection<File> = emptyList()
@@ -129,15 +129,8 @@ abstract class IncrementalCompilerRunner<
                 else -> providedChangedFiles
             }
 
-            // 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)
-            }
+            @Suppress("MoveVariableDeclarationIntoWhen")
+            val compilationMode = sourcesToCompile(caches, changedFiles, args, messageCollector, classpathAbiSnapshot)
 
             val exitCode = when (compilationMode) {
                 is CompilationMode.Incremental -> {

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

@@ -118,8 +118,10 @@ class IncrementalJsCompilerRunner(
         messageCollector: MessageCollector,
         classpathAbiSnapshots: Map<String, AbiSnapshot> //Ignore for now
     ): CompilationMode {
+        if (!withSnapshot && !buildHistoryFile.isFile) {
+            return CompilationMode.Rebuild(BuildAttribute.NO_BUILD_HISTORY)
+        }
         val lastBuildInfo = BuildInfo.read(lastBuildInfoFile)
-            ?: return CompilationMode.Rebuild(BuildAttribute.NO_BUILD_HISTORY)
 
         val dirtyFiles = DirtyFilesContainer(caches, reporter, kotlinSourceFilesExtensions)
         initDirtyFiles(dirtyFiles, changedFiles)

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

@@ -256,7 +256,14 @@ 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.NO_BUILD_HISTORY)
+                if (!withSnapshot && !buildHistoryFile.isFile) {
+                    // If the previous build was a Gradle cache hit, the build history file must have been deleted as it is marked as
+                    // @LocalState in the Gradle task. Therefore, this compilation will need to run non-incrementally.
+                    // (Note that buildHistoryFile is outside workingDir. We don't need to perform the same check for files inside
+                    // workingDir as workingDir is an @OutputDirectory, so the files must be present in an incremental build.)
+                    return CompilationMode.Rebuild(BuildAttribute.NO_BUILD_HISTORY)
+                }
+                val lastBuildInfo = BuildInfo.read(lastBuildInfoFile)
                 reporter.reportVerbose { "Last Kotlin Build info -- $lastBuildInfo" }
                 val scopes = caches.lookupCache.lookupSymbols.map { it.scope.ifBlank { it.name } }.distinct()