Support java-test-fixtures plugin

Applying 'java-test-fixtures' plugin caused 'No mutations found'
from Pitest.

The plugin changes test runtime classpath:
tested code is included as a JAR instead of as a directory
(see gradle/gradle#11696). It seems that Pitest ignores correct
directories being passed using --mutableCodePaths and insists on
having those directories also passed in --classPath.

Also change functional tests: runTasksSuccessfully() fails the test
without giving any context, so it should be avoided.

src/funcTest/groovy/info/solidsoft/gradle/pitest/functional/Junit5FunctionalSpec.groovy

@@ -11,8 +11,10 @@ class Junit5FunctionalSpec extends AbstractPitestFunctionalSpec {
         given:
             copyResources("testProjects/junit5kotlin", "")
         when:
-            ExecutionResult result = runTasksSuccessfully('pitest')
+            ExecutionResult result = runTasks('pitest')
         then:
+            !result.standardError.contains("Build failed with an exception")
+            !result.failure
             result.wasExecuted('pitest')
             result.standardOutput.contains('Generated 2 mutations Killed 2 (100%)')
     }
@@ -21,8 +23,10 @@ class Junit5FunctionalSpec extends AbstractPitestFunctionalSpec {
         given:
             copyResources("testProjects/junit5kotlin", "")
         when:
-            ExecutionResult result = runTasksSuccessfully('pitest', '-b', 'build.gradle.kts')
+            ExecutionResult result = runTasks('pitest')
         then:
+            !result.standardError.contains("Build failed with an exception")
+            !result.failure
             result.wasExecuted('pitest')
             result.standardOutput.contains('Generated 2 mutations Killed 2 (100%)')
     }
@@ -32,8 +36,10 @@ class Junit5FunctionalSpec extends AbstractPitestFunctionalSpec {
         given:
             copyResources("testProjects/junit5simple", "")
         when:
-            ExecutionResult result = runTasksSuccessfully('pitest')
+            ExecutionResult result = runTasks('pitest')
         then:
+            !result.standardError.contains("Build failed with an exception")
+            !result.failure
             result.wasExecuted('pitest')
         and:
             result.standardOutput.contains('--testPlugin=junit5')

src/funcTest/groovy/info/solidsoft/gradle/pitest/functional/TestFixturesFunctionalSpec.groovy

@@ -0,0 +1,21 @@
+package info.solidsoft.gradle.pitest.functional
+
+import groovy.transform.CompileDynamic
+import nebula.test.functional.ExecutionResult
+
+@CompileDynamic
+class TestFixturesFunctionalSpec extends AbstractPitestFunctionalSpec {
+
+    void "should work with kotlin and test fixtures"() {
+        given:
+            copyResources("testProjects/testFixtures", "")
+        when:
+            ExecutionResult result = runTasks('pitest')
+        then:
+            !result.standardError.contains("Build failed with an exception")
+            !result.failure
+            result.wasExecuted('pitest')
+            result.standardOutput.contains('Generated 1 mutations Killed 1 (100%)')
+    }
+
+}

src/funcTest/resources/testProjects/testFixtures/build.gradle

@@ -0,0 +1,24 @@
+apply plugin: 'java-library'
+apply plugin: 'java-test-fixtures'
+apply plugin: 'info.solidsoft.pitest'
+
+buildscript {
+    repositories {
+        mavenCentral()
+        mavenLocal()
+    }
+    dependencies {
+        //Local/current version of the plugin should be put on a classpath earlier to override that plugin version
+//        classpath 'info.solidsoft.gradle.pitest:gradle-pitest-plugin:1.1.7-SNAPSHOT'
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+group = "pitest.test"
+
+dependencies {
+    testImplementation 'junit:junit:4.12'
+}

src/funcTest/resources/testProjects/testFixtures/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'testFixtures'

src/funcTest/resources/testProjects/testFixtures/src/main/java/pitest/test/Library.java

@@ -0,0 +1,7 @@
+package pitest.test;
+
+public class Library {
+    public boolean someLibraryMethod() {
+        return true;
+    }
+}

src/funcTest/resources/testProjects/testFixtures/src/test/java/pitest/test/LibraryTest.java

@@ -0,0 +1,13 @@
+package pitest.test;
+
+import org.junit.Test;
+import pitest.test.Library;
+
+import static org.junit.Assert.*;
+
+public class LibraryTest {
+    @Test public void testSomeLibraryMethod() {
+        Library classUnderTest = new Library();
+        assertTrue("someLibraryMethod should return 'true'", classUnderTest.someLibraryMethod());
+    }
+}

src/main/groovy/info/solidsoft/gradle/pitest/PitestPlugin.groovy

@@ -170,19 +170,20 @@ class PitestPlugin implements Plugin<Project> {
         task.sourceDirs.setFrom(extension.mainSourceSets.map { mainSourceSet -> mainSourceSet*.allSource*.srcDirs })
         task.detectInlinedCode.set(extension.detectInlinedCode)
         task.timestampedReports.set(extension.timestampedReports)
+        Callable<Set<File>> allMutableCodePaths = {
+            calculateBaseMutableCodePaths() + (extension.additionalMutableCodePaths.getOrElse([] as Set) as Set<File>)
+        }
         task.additionalClasspath.setFrom({
             List<FileCollection> testRuntimeClasspath = (extension.testSourceSets.get() as Set<SourceSet>)*.runtimeClasspath
             FileCollection combinedTaskClasspath = project.objects.fileCollection().from(testRuntimeClasspath)
             FileCollection filteredCombinedTaskClasspath = combinedTaskClasspath.filter { File file ->
-                !extension.fileExtensionsToFilter.getOrElse([]).find { extension -> file.name.endsWith(".$extension") }
-            }
+                !extension.fileExtensionsToFilter.getOrElse([]).find { extension -> file.name.endsWith(".$extension") || file == "core.jar" }
+            } + project.files(allMutableCodePaths)
             return filteredCombinedTaskClasspath
         } as Callable<FileCollection>)
         task.useAdditionalClasspathFile.set(extension.useClasspathFile)
         //additionalClasspathFile - separate method
-        task.mutableCodePaths.setFrom({
-            calculateBaseMutableCodePaths() + (extension.additionalMutableCodePaths.getOrElse([] as Set) as Set<File>)
-        } as Callable<Set<File>>)
+        task.mutableCodePaths.setFrom(allMutableCodePaths)
         task.historyInputLocation.set(extension.historyInputLocation)
         task.historyOutputLocation.set(extension.historyOutputLocation)
         task.enableDefaultIncrementalAnalysis.set(extension.enableDefaultIncrementalAnalysis)

src/test/groovy/info/solidsoft/gradle/pitest/PitestTaskConfigurationSpec.groovy

@@ -244,7 +244,11 @@ class PitestTaskConfigurationSpec extends BasicProjectBuilderSpec implements Wit
             project.sourceSets { intTest }
             project.pitest.testSourceSets = [project.sourceSets.intTest]
         expect:
-            task.taskArgumentMap()['classPath'] == assembleSourceSetsClasspathByNameAsStringSet("intTest").join(",")
+            task.taskArgumentMap()['classPath'] ==
+                (
+                    assembleSourceSetsClasspathByNameAsStringSet("intTest") +
+                    ["${project.buildDir}/classes/java/main"]
+                ).join(",")
     }
 
     private Set<String> assembleSourceSetsClasspathByNameAsStringSet(List<String> sourceSetNames) {
@@ -254,8 +258,8 @@ class PitestTaskConfigurationSpec extends BasicProjectBuilderSpec implements Wit
     }
 
     private Set<String> assembleSourceSetsClasspathByNameAsStringSet(String sourceSetName) {
-        return [new File(project.buildDir, "classes//java//${sourceSetName}"),
-                new File(project.buildDir, "resources//${sourceSetName}")
+        return [new File(project.buildDir, "classes/java/${sourceSetName}"),
+                new File(project.buildDir, "resources/${sourceSetName}")
         ]*.absolutePath
     }