use stable temp dir for test projects

Author: aSemy

modules/bcv-gradle-plugin-functional-tests/build.gradle.kts

@@ -59,13 +59,13 @@ testing.suites {
           "devMavenRepoDir",
           devPublish.devMavenRepo.asFile.get().invariantSeparatorsPath,
         )
-        val tmpDir = layout.buildDirectory.dir("test-temp").get().asFile
+        val testTempDir = layout.buildDirectory.dir("test-temp").get().asFile
         systemProperty(
-          "java.io.tmpdir",
-          tmpDir.absoluteFile.invariantSeparatorsPath
+          "testTempDir",
+          testTempDir.invariantSeparatorsPath
         )
         doFirst {
-          tmpDir.mkdirs()
+          testTempDir.mkdirs()
         }
       }
     }

modules/bcv-gradle-plugin-functional-tests/src/testFixtures/kotlin/TempDirFactory.kt

@@ -0,0 +1,52 @@
+package dev.adamko.kotlin.binary_compatibility_validator.test.utils
+
+import java.nio.file.Path
+import kotlin.io.path.ExperimentalPathApi
+import kotlin.io.path.Path
+import kotlin.io.path.createDirectories
+import kotlin.io.path.deleteRecursively
+import kotlin.jvm.optionals.getOrNull
+import org.junit.jupiter.api.extension.AnnotatedElementContext
+import org.junit.jupiter.api.extension.ExtensionContext
+import org.junit.jupiter.api.io.TempDirFactory
+
+/**
+ * Create temp dir with a stable name based on the current test name.
+ *
+ * @see TempDirFactory.Standard
+ */
+class TempTestNameDirFactory : TempDirFactory {
+
+  @OptIn(ExperimentalPathApi::class)
+  override fun createTempDirectory(
+    elementContext: AnnotatedElementContext,
+    extensionContext: ExtensionContext,
+  ): Path {
+
+    // convert `${TestClass.fqn}.${testDisplayName}`
+    // to file path, e.g. `f/q/n/TestClass/test-display-name`
+    val path = listOfNotNull(
+      extensionContext.testClass.getOrNull()?.canonicalName,
+      extensionContext.displayName,
+    ).joinToString("/") { segment ->
+      segment
+        .split(".")
+        .joinToString(separator = "/") {
+          it
+            .map { c -> if (c.isLetterOrDigit()) c else '-' }
+            .dropLastWhile(Char::isLetterOrDigit)
+            .dropWhile(Char::isLetterOrDigit)
+            .joinToString("")
+        }
+    }
+
+    val dir = testTempDir.resolve(path)
+    dir.deleteRecursively()
+    dir.createDirectories()
+    return dir
+  }
+
+  companion object {
+    private val testTempDir: Path by systemProperty(::Path)
+  }
+}

modules/bcv-gradle-plugin-functional-tests/src/testFixtures/kotlin/api/BaseKotlinGradleTest.kt

@@ -1,11 +1,15 @@
 package dev.adamko.kotlin.binary_compatibility_validator.test.utils.api
 
+import dev.adamko.kotlin.binary_compatibility_validator.test.utils.TempTestNameDirFactory
 import java.io.File
 import org.junit.jupiter.api.io.CleanupMode.ON_SUCCESS
 import org.junit.jupiter.api.io.TempDir
 
 open class BaseKotlinGradleTest {
-  @TempDir(cleanup = ON_SUCCESS)
+  @TempDir(
+    factory = TempTestNameDirFactory::class,
+    cleanup = ON_SUCCESS,
+  )
   lateinit var testTempDir: File
 
   val rootProjectDir: File get() = testTempDir.resolve("bcv-test-project")

modules/bcv-gradle-plugin-functional-tests/src/testFixtures/kotlin/systemProperties.kt

@@ -0,0 +1,14 @@
+package dev.adamko.kotlin.binary_compatibility_validator.test.utils
+
+import kotlin.properties.ReadOnlyProperty
+
+
+internal fun <T> systemProperty(
+  convert: (String) -> T
+): ReadOnlyProperty<Any, T> =
+  ReadOnlyProperty { _, property ->
+    val value = requireNotNull(System.getProperty(property.name)) {
+      "system property ${property.name} is unavailable"
+    }
+    convert(value)
+  }