Allow partly parallel Maven execution (#557)

Author: nedtwigg

jvm/CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [2.5.4] - 2025-09-12
 ### Fixed
 - Unsupported test sources (such as `FieldSource`) no longer cause the JUnit5 runner to crash. ([#550](https://github.com/diffplug/selfie/pull/550) fixes [#549](https://github.com/diffplug/selfie/issues/549))
+- Partly allow parallel Maven execution with surefire and failsafe plugins with `forkCount` greater than one by making evaluation of few properties lazy. This postpones evaluation into the forks. Still, due to internal Selfie state tracking, this needs to be run with `reuseForks` set to `false`. ([#557](https://github.com/diffplug/selfie/pull/557) partly fixes [#551](https://github.com/diffplug/selfie/issues/551))
 ### Changed
 - Bump minimum required Kotest from `5.4.0` to `5.6.0` ([#535](https://github.com/diffplug/selfie/pull/535))
   - required to fix `java.lang.NoSuchMethodError: 'long kotlin.time.Duration$Companion.milliseconds-UwyO8pc(long)'`

jvm/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/junit5/SnapshotFileLayoutJUnit5.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023-2024 DiffPlug
+ * Copyright (C) 2023-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,13 +27,16 @@ class SnapshotFileLayoutJUnit5(settings: SelfieSettingsAPI, override val fs: FS)
   internal val smuggledError =
       AtomicReference<Throwable?>(
           if (settings is SelfieSettingsSmuggleError) settings.error else null)
-  override val rootFolder = TypedPath.ofFolder(settings.rootFolder.absolutePath)
-  private val otherSourceRoots = settings.otherSourceRoots
+  internal val settings = settings
+  override val rootFolder: TypedPath by lazy {
+    TypedPath.ofFolder(settings.rootFolder.absolutePath)
+  }
+  private val otherSourceRoots: List<java.io.File> by lazy { settings.otherSourceRoots }
   override val allowMultipleEquivalentWritesToOneLocation =
       settings.allowMultipleEquivalentWritesToOneLocation
   override val javaDontUseTripleQuoteLiterals = settings.javaDontUseTripleQuoteLiterals
   val snapshotFolderName = settings.snapshotFolderName
-  internal val unixNewlines = inferDefaultLineEndingIsUnix(rootFolder, fs)
+  internal val unixNewlines: Boolean by lazy { inferDefaultLineEndingIsUnix(rootFolder, fs) }
   val extension: String = ".ss"
   private val cache =
       SourcePathCache(this::computePathForCall, Runtime.getRuntime().availableProcessors() * 4)

jvm/selfie-runner-kotest/src/commonMain/kotlin/com/diffplug/selfie/kotest/SnapshotFileLayoutKotest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 DiffPlug
+ * Copyright (C) 2024-2025 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.