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/pom.xml

@@ -8,7 +8,7 @@
 		<relativePath>../spring-boot-parent</relativePath>
 	</parent>
 	<artifactId>spring-boot-integration-tests</artifactId>
-	<packaging>pom</packaging>
+	<packaging>jar</packaging>
 	<name>Spring Boot Integration Tests</name>
 	<description>Spring Boot Integration Tests</description>
 	<url>http://projects.spring.io/spring-boot/</url>
@@ -19,6 +19,19 @@
 	<properties>
 		<main.basedir>${basedir}/..</main.basedir>
 	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>org.gradle</groupId>
+			<artifactId>gradle-tooling-api</artifactId>
+			<version>${gradle.version}</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-dependency-tools</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
 	<profiles>
 		<profile>
 			<id>default</id>
@@ -57,4 +70,16 @@
 			<id>full</id>
 		</profile>
 	</profiles>
+	<repositories>
+		<repository>
+			<id>gradle</id>
+			<url>http://repo.gradle.org/gradle/libs-releases-local</url>
+			<releases>
+				<enabled>true</enabled>
+			</releases>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
 </project>

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());
+		}
+	}
+}

spring-boot-integration-tests/src/test/resources/build.gradle

@@ -0,0 +1,49 @@
+import org.gradle.api.artifacts.result.UnresolvedDependencyResult;
+
+repositories {
+	mavenLocal()
+	mavenCentral()
+}
+
+configurations {
+	springBootStarter
+}
+
+dependencies {
+	springBootStarter "org.springframework.boot:${project.starter}:${project.bootVersion}"
+}
+
+task checkCommonsLogging {
+	doFirst {
+		def commonsLogging = resolvedDependencies
+				.find { it.selected.id.group == 'commons-logging' }
+		if (commonsLogging) {
+			throw new GradleException("${project.starter} pulls in commons-logging")
+		}
+	}
+}
+
+task checkSpring {
+	doFirst {
+		def wrongSpring = resolvedDependencies
+				.findAll{it.selected.id.group == 'org.springframework'}
+				.findAll{it.selected.id.version != project.springVersion}
+				.collect {it.selected.id}
+		if (wrongSpring) {
+			throw new GradleException("${project.starter} pulled in ${wrongSpring as Set}")
+		}
+	}
+}
+
+def getResolvedDependencies() {
+	def allDependencies = configurations.springBootStarter.incoming
+			.resolutionResult.allDependencies
+					.split { it instanceof UnresolvedDependencyResult }
+
+	def unresolved = allDependencies.first()
+	def resolved = allDependencies.last()
+	if (unresolved) {
+		throw new GradleException("Resolution of ${project.starter} failed: ${unresolved}")
+	}
+	resolved
+}