Introduce GradleProject class.

This allows to split concepts of TestProject(whole build and options)
and actual Gradle project, which could be one of the main project
subprojects.

^KT-45745 In Progress

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

@@ -77,7 +77,7 @@ class BuildCacheIT : KGPBaseTest() {
                 assertTasksPackedToCache(":compileKotlin")
             }
 
-            val sourceFile = projectPath.resolve("src/main/kotlin/helloWorld.kt")
+            val sourceFile = kotlinSourcesDir().resolve("helloWorld.kt")
             val originalSource: String = sourceFile.readText()
             val modifiedSource: String = originalSource.replace(" and ", " + ")
             sourceFile.writeText(modifiedSource)
@@ -187,7 +187,7 @@ class BuildCacheIT : 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.projectPath.resolve("src/main/kotlin/foo.kt")
+        val fooKtSourceFile = secondProject.kotlinSourcesDir().resolve("foo.kt")
         fooKtSourceFile.modify { it.replace("Int = 1", "String = \"abc\"") }
         secondProject.build("assemble") {
             assertIncrementalCompilation(modifiedFiles = setOf(fooKtSourceFile))
@@ -224,7 +224,7 @@ class BuildCacheIT : KGPBaseTest() {
         }
 
         // Make changes to annotated class and check kapt tasks are re-executed
-        val appClassKtSourceFile = secondProject.projectPath.resolve("app/src/main/kotlin/AppClass.kt")
+        val appClassKtSourceFile = secondProject.subProject("app").kotlinSourcesDir().resolve("AppClass.kt")
         appClassKtSourceFile.modify {
             it.replace("val testVal: String = \"text\"", "val testVal: Int = 1")
         }

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

@@ -8,12 +8,9 @@ package org.jetbrains.kotlin.gradle
 import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.DisplayName
-import kotlin.io.path.ExperimentalPathApi
-import kotlin.io.path.appendText
 
 @DisplayName("Tasks configuration avoidance")
 @SimpleGradlePluginTests
-@OptIn(ExperimentalPathApi::class)
 class ConfigurationAvoidanceIT : KGPBaseTest() {
 
     @DisplayName("Unrelated tasks are not configured")
@@ -24,7 +21,7 @@ class ConfigurationAvoidanceIT : KGPBaseTest() {
             val expensivelyConfiguredTaskName = "expensivelyConfiguredTask"
 
             @Suppress("GroovyAssignabilityCheck")
-            rootBuildGradle.appendText(
+            buildGradle.append(
                 //language=Groovy
                 """
                     
@@ -48,10 +45,9 @@ class ConfigurationAvoidanceIT : KGPBaseTest() {
         ) {
 
             listOf("Android", "Test").forEach { subproject ->
-                projectPath
+                subProject(subproject)
-                    .resolve(subproject)
+                    .buildGradle
-                    .resolve("build.gradle")
+                    .append(
-                    .appendText(
                         //language=Groovy
                         """
                         
@@ -66,10 +62,9 @@ class ConfigurationAvoidanceIT : KGPBaseTest() {
                     )
             }
 
-            projectPath
+            subProject("Lib")
-                .resolve("Lib")
+                .buildGradle
-                .resolve("build.gradle")
+                .append(
-                .appendText(
                     //language=Groovy
                     """
                     

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

@@ -25,7 +25,7 @@ class JavaUpToDateIT : KGPBaseTest() {
                 )
             }
 
-            projectPath.resolve("src/main/kotlin/foo/MainKotlinClass.kt").modify {
+            kotlinSourcesDir().resolve("foo/MainKotlinClass.kt").modify {
                 it.replace(
                     "fun number(): Int = 0",
                     "fun number(): Int = 1"
@@ -52,7 +52,7 @@ class JavaUpToDateIT : KGPBaseTest() {
                 )
             }
 
-            projectPath.resolve("src/main/kotlin/foo/MainKotlinClass.kt").modify { "\n$it" }
+            kotlinSourcesDir().resolve("foo/MainKotlinClass.kt").modify { "\n$it" }
 
             build("build") {
                 assertTasksExecuted(":compileKotlin", ":compileTestKotlin")
@@ -74,7 +74,7 @@ class JavaUpToDateIT : KGPBaseTest() {
                 )
             }
 
-            projectPath.resolve("src/main/kotlin/foo/MainKotlinClass.kt").modify {
+            kotlinSourcesDir().resolve("foo/MainKotlinClass.kt").modify {
                 it.replace(
                     "private fun privateMethod() = 0",
                     "private fun privateMethod() = \"0\""

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

@@ -131,7 +131,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
 
             JavaVersion.VERSION_1_8
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 tasks
@@ -168,7 +168,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
             gradleVersion = gradleVersion
         ) {
             //language=groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 java {
@@ -208,7 +208,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
                 kotlin.jvm.target.validation.mode = error
                 """.trimIndent()
             )
-            projectPath.resolve("src/main/kotlin").toFile().deleteRecursively()
+            kotlinSourcesDir().toFile().deleteRecursively()
 
             buildAndFail("assemble") {
                 assertOutputContains(
@@ -269,7 +269,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
                 )
             }
 
-            projectPath.resolve("src/main/java/demo").run {
+            javaSourcesDir().resolve("demo").run {
                 createDirectories()
                 resolve("HelloWorld.java").writeText(
                     //language=Java
@@ -297,7 +297,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
         target: JavaVersion
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
 
             tasks.withType(JavaCompile.class).configureEach {
@@ -313,7 +313,7 @@ class JvmTargetValidationTest : KGPBaseTest() {
         jdkVersion: Int
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
             import org.jetbrains.kotlin.gradle.tasks.UsesKotlinJavaToolchain
             

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

@@ -12,7 +12,6 @@ import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.AfterEach
 import org.junit.jupiter.api.DisplayName
-import org.junit.jupiter.api.Test
 
 @DaemonsGradlePluginTests
 @DisplayName("Kotlin daemon JVM args")
@@ -92,7 +91,7 @@ class KotlinDaemonJvmArgsTest : KGPBaseTest() {
             )
 
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 kotlin {
@@ -125,7 +124,7 @@ class KotlinDaemonJvmArgsTest : KGPBaseTest() {
             )
 
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 import org.jetbrains.kotlin.gradle.tasks.CompileUsingKotlinDaemon
@@ -162,7 +161,7 @@ class KotlinDaemonJvmArgsTest : KGPBaseTest() {
             )
 
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 kotlin {

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

@@ -312,7 +312,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             gradleVersion = gradleVersion
         ) {
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 import org.jetbrains.kotlin.gradle.dsl.KotlinCompile
                 
@@ -464,7 +464,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             gradleVersion = gradleVersion
         ) {
             //language=groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 java {
@@ -498,7 +498,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             useToolchainToCompile(11)
 
             //language=groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 
                 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
@@ -568,7 +568,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
             buildJdk = getJdk11().javaHome
         ) {
             //language=Groovy
-            rootBuildGradle.append(
+            buildGradle.append(
                 """
                 tasks.named("compileKotlin") {
                     doLast {
@@ -659,7 +659,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         jvmTarget: String
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
             import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
             
@@ -676,7 +676,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         target: JavaVersion
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
 
             tasks.withType(JavaCompile.class).configureEach {
@@ -693,7 +693,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         jdkVersion: JavaVersion
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
             import org.gradle.api.JavaVersion
             import org.jetbrains.kotlin.gradle.tasks.UsesKotlinJavaToolchain
@@ -714,7 +714,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         jdkVersion: Int
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
             import org.jetbrains.kotlin.gradle.tasks.UsesKotlinJavaToolchain
             
@@ -742,7 +742,7 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         jdkVersion: Int
     ) {
         //language=Groovy
-        rootBuildGradle.append(
+        buildGradle.append(
             """
             import org.gradle.api.plugins.JavaPluginExtension
             import org.gradle.jvm.toolchain.JavaLanguageVersion

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

@@ -121,7 +121,7 @@ class SimpleKotlinGradleIT : KGPBaseTest() {
         project("kotlinProject", gradleVersion) {
             // Change the build directory in the end of the build script:
             val customBuildDirName = "customBuild"
-            appendToBuildFile(
+            buildGradle.append(
                 "buildDir = '$customBuildDirName'"
             )
 

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

@@ -65,7 +65,7 @@ class SourceFileIsModifiedIT : KGPBaseTest() {
                 assertTasksNoSource(":compileTestKotlin")
             }
 
-            val dummyFile = projectPath.resolve("src/main/java/kotlinPackage/Dummy.kt")
+            val dummyFile = javaSourcesDir().resolve("kotlinPackage/Dummy.kt")
             transformDummy(dummyFile)
 
             build("build", buildOptions = buildOptions) {

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

@@ -11,7 +11,7 @@ import java.nio.file.Path
 /**
  * Asserts file under [file] path exists and is a regular file.
  */
-fun TestProject.assertFileExists(
+fun GradleProject.assertFileExists(
     file: Path
 ) {
     assert(Files.exists(file)) {
@@ -26,7 +26,7 @@ fun TestProject.assertFileExists(
 /**
  * Asserts file under [pathToFile] relative to the test project exists and is a regular file.
  */
-fun TestProject.assertFileInProjectExists(
+fun GradleProject.assertFileInProjectExists(
     pathToFile: String
 ) {
     assertFileExists(projectPath.resolve(pathToFile))
@@ -35,7 +35,7 @@ fun TestProject.assertFileInProjectExists(
 /**
  * Asserts file under [pathToFile] relative to the test project does not exist.
  */
-fun TestProject.assertFileNotExists(
+fun GradleProject.assertFileNotExists(
     pathToFile: String
 ) {
     val filePath = projectPath.resolve(pathToFile)
@@ -47,7 +47,7 @@ fun TestProject.assertFileNotExists(
 /**
  * Asserts directory under [pathToDir] relative to the test project exists and is a directory.
  */
-fun TestProject.assertDirectoryExists(
+fun GradleProject.assertDirectoryExists(
     pathToDir: String
 ) {
     val dirPath = projectPath.resolve(pathToDir)

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

@@ -57,8 +57,8 @@ fun KGPBaseTest.project(
     val testProject = TestProject(
         gradleRunner,
         projectName,
-        buildOptions,
         projectPath,
+        buildOptions,
         gradleVersion,
         enableGradleDebug,
         forceOutput,
@@ -151,20 +151,15 @@ fun TestProject.enableLocalBuildCache(
     )
 }
 
-class TestProject(
+open class GradleProject(
-    val gradleRunner: GradleRunner,
     val projectName: String,
-    val buildOptions: KGPBaseTest.BuildOptions,
+    val projectPath: Path
-    val projectPath: Path,
-    val gradleVersion: GradleVersion,
-    val enableGradleDebug: Boolean,
-    val forceOutput: Boolean,
-    val enableBuildScan: Boolean
 ) {
-    val rootBuildGradle: Path get() = projectPath.resolve("build.gradle")
+    val buildGradle: Path get() = projectPath.resolve("build.gradle")
+    val buildGradleKts: Path get() = projectPath.resolve("build.gradle.kts")
     val settingsGradle: Path get() = projectPath.resolve("settings.gradle")
+    val settingsGradleKts: Path get() = projectPath.resolve("settings.gradle.kts")
     val gradleProperties: Path get() = projectPath.resolve("gradle.properties")
-    val localProperties: Path get() = projectPath.resolve("local.properties")
 
     fun classesDir(
         sourceSet: String = "main",
@@ -174,6 +169,27 @@ class TestProject(
     fun kotlinClassesDir(
         sourceSet: String = "main"
     ): Path = classesDir(sourceSet, language = "kotlin")
+
+    fun kotlinSourcesDir(
+        sourceSet: String = "main"
+    ): Path = projectPath.resolve("src/$sourceSet/kotlin")
+
+    fun javaSourcesDir(
+        sourceSet: String = "main"
+    ): Path = projectPath.resolve("src/$sourceSet/java")
+}
+
+class TestProject(
+    val gradleRunner: GradleRunner,
+    projectName: String,
+    projectPath: Path,
+    val buildOptions: KGPBaseTest.BuildOptions,
+    val gradleVersion: GradleVersion,
+    val enableGradleDebug: Boolean,
+    val forceOutput: Boolean,
+    val enableBuildScan: Boolean
+) : GradleProject(projectName, projectPath) {
+    fun subProject(name: String) = GradleProject(name, projectPath.resolve(name))
 }
 
 private fun commonBuildSetup(
@@ -264,9 +280,8 @@ private fun Path.addDefaultBuildFiles() {
     }
 }
 
-@OptIn(ExperimentalPathApi::class)
 private fun TestProject.agreeToBuildScanService() {
-    settingsGradle.appendText(
+    settingsGradle.append(
         """
             
         gradleEnterprise {

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

@@ -34,12 +34,3 @@ fun Path.append(
         """.trimIndent()
     }
 }
-
-/**
- * Append [textToAppend] to the current [TestProject] 'build.gradle' file.
- */
-fun TestProject.appendToBuildFile(
-    textToAppend: String
-) {
-    projectPath.resolve("build.gradle").append(textToAppend)
-}