Add tests to verify starter dependencies when used with Gradle

We've had problems with the starters when used with Gradle. They have
been pulling in commons-logging (#987) and the wrong version of Spring
(#1028) due to Gradle's different exclusion and dependency resolution
semantics.

This commit adds some integration tests that use Gradle's tooling API
to take each starter in turn and build a Gradle project that depends
upon it. The build looks at the transitive dependencies and checks
that neither commons-logging nor any Spring modules with the wrong
version are present.

Closes #1036

spring-boot-integration-tests/src/test/java/org/springframework/boot/starter/StarterDependenciesIntegrationTests.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2012-2014 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.starter;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.gradle.tooling.BuildException;
+import org.gradle.tooling.GradleConnector;
+import org.gradle.tooling.ProjectConnection;
+import org.gradle.tooling.internal.consumer.DefaultGradleConnector;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+import org.springframework.boot.dependency.tools.VersionManagedDependencies;
+import org.springframework.util.FileCopyUtils;
+
+import static org.junit.Assert.fail;
+
+/**
+ * Tests for the various starter projects to check that they don't pull in unwanted
+ * transitive dependencies when used with Gradle
+ *
+ * @author Andy Wilkinson
+ */
+@RunWith(Parameterized.class)
+public class StarterDependenciesIntegrationTests {
+
+	private static final String STARTER_NAME_PREFIX = "spring-boot-starter";
+
+	private static final List<String> EXCLUDED_STARTERS = Arrays
+			.asList("spring-boot-starter-parent");
+
+	private static ProjectConnection project;
+
+	private static String bootVersion;
+
+	private static String springVersion;
+
+	private final String[] buildArguments;
+
+	@Parameters
+	public static List<String[]> getStarters() {
+		List<String[]> starters = new ArrayList<String[]>();
+		for (File file : new File("../spring-boot-starters").listFiles()) {
+			if (file.isDirectory()) {
+				String name = file.getName();
+				if (name.startsWith(STARTER_NAME_PREFIX)
+						&& !EXCLUDED_STARTERS.contains(file.getName())) {
+					starters.add(new String[] { file.getName() });
+				}
+			}
+		}
+		return starters;
+	}
+
+	@BeforeClass
+	public static void createProject() throws IOException {
+		File projectDirectory = new File("target/starter-dependencies");
+		projectDirectory.mkdirs();
+
+		File gradleScript = new File(projectDirectory, "build.gradle");
+		FileCopyUtils.copy(new File("src/test/resources/build.gradle"), gradleScript);
+
+		GradleConnector gradleConnector = GradleConnector.newConnector();
+		((DefaultGradleConnector) gradleConnector).embedded(true);
+		project = gradleConnector.forProjectDirectory(projectDirectory).connect();
+	}
+
+	@BeforeClass
+	public static void determineVersions() throws Exception {
+		springVersion = new VersionManagedDependencies().find("spring-core").getVersion();
+		bootVersion = new VersionManagedDependencies().find("spring-boot").getVersion();
+	}
+
+	@AfterClass
+	public static void closeProject() {
+		project.close();
+	}
+
+	public StarterDependenciesIntegrationTests(String starter) {
+		this.buildArguments = new String[] { "-Pstarter=" + starter,
+				"-PbootVersion=" + bootVersion, "-PspringVersion=" + springVersion };
+	}
+
+	@Test
+	public void commonsLoggingIsNotATransitiveDependency() throws IOException {
+		runBuildForTask("checkCommonsLogging");
+	}
+
+	@Test
+	public void oldSpringModulesAreNotTransitiveDependencies() throws IOException {
+		runBuildForTask("checkSpring");
+	}
+
+	private void runBuildForTask(String task) {
+		try {
+			project.newBuild().forTasks(task).withArguments(this.buildArguments).run();
+		}
+		catch (BuildException ex) {
+			Throwable root = ex;
+			while (root.getCause() != null) {
+				root = root.getCause();
+			}
+			fail(root.getMessage());
+		}
+	}
+}