Minimize and centralize assumptions about build output

Closes gh-15471

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/BuildOutput.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2012-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.testsupport;
+
+import java.io.File;
+import java.net.URISyntaxException;
+
+/**
+ * Provides access to build output locations in a build system and IDE agnostic manner.
+ *
+ * @author Andy Wilkinson
+ */
+public class BuildOutput {
+
+	private final Class<?> testClass;
+
+	public BuildOutput(Class<?> testClass) {
+		this.testClass = testClass;
+	}
+
+	/**
+	 * Returns the location into which test classes have been built.
+	 * @return test classes location
+	 */
+	public File getTestClassesLocation() {
+		try {
+			File location = new File(this.testClass.getProtectionDomain().getCodeSource()
+					.getLocation().toURI());
+			if (location.getPath().endsWith(path("target", "test-classes"))) {
+				return location;
+			}
+			throw new IllegalStateException(
+					"Unexpected test classes location '" + location + "'");
+		}
+		catch (URISyntaxException ex) {
+			throw new IllegalStateException("Invalid test class code source location",
+					ex);
+		}
+	}
+
+	/**
+	 * Returns the location into which test resources have been built.
+	 * @return test resources location
+	 */
+	public File getTestResourcesLocation() {
+		File testClassesLocation = getTestClassesLocation();
+		if (testClassesLocation.getPath().endsWith(path("target", "test-classes"))) {
+			return testClassesLocation;
+		}
+		throw new IllegalStateException(
+				"Cannot determine test resources location from classes location '"
+						+ testClassesLocation + "'");
+	}
+
+	/**
+	 * Returns the root location into which build output is written.
+	 * @return root location
+	 */
+	public File getRootLocation() {
+		return getTestClassesLocation().getParentFile();
+	}
+
+	private String path(String... components) {
+		return File.separator + String.join(File.separator, components);
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/context/AbstractConfigurationClassTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,6 @@
 
 package org.springframework.boot.testsupport.context;
 
-import java.io.File;
 import java.io.IOException;
 import java.util.HashSet;
 import java.util.Set;
@@ -25,6 +24,7 @@ import org.junit.Test;
 
 import org.springframework.asm.Opcodes;
 import org.springframework.beans.DirectFieldAccessor;
+import org.springframework.boot.testsupport.BuildOutput;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.io.Resource;
@@ -44,6 +44,8 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 public abstract class AbstractConfigurationClassTests {
 
+	private final BuildOutput buildOutput = new BuildOutput(getClass());
+
 	private ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
 
 	@Test
@@ -83,7 +85,7 @@ public abstract class AbstractConfigurationClassTests {
 
 	private boolean isTestClass(Resource resource) throws IOException {
 		return resource.getFile().getAbsolutePath()
-				.contains("target" + File.separator + "test-classes");
+				.startsWith(this.buildOutput.getTestClassesLocation().getAbsolutePath());
 	}
 
 	private boolean isPublic(MethodMetadata methodMetadata) {