Grab main class from "run" task if it exists

The test is a bit crap at the minute (no assertion), but the build
is successful and you can see from the log that the correct main
is used

Fixes gh-1099

spring-boot-integration-tests/src/test/java/org/springframework/boot/gradle/MainClassTests.java

@@ -0,0 +1,48 @@
+/*
+ * 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.gradle;
+
+import java.io.IOException;
+
+import org.gradle.tooling.ProjectConnection;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.springframework.boot.dependency.tools.ManagedDependencies;
+
+/**
+ * Tests for using the Gradle plugin's support for installing artifacts
+ *
+ * @author Dave Syer
+ */
+public class MainClassTests {
+
+	private static ProjectConnection project;
+
+	private static final String BOOT_VERSION = ManagedDependencies.get()
+			.find("spring-boot").getVersion();
+
+	@BeforeClass
+	public static void createProject() throws IOException {
+		project = new ProjectCreator().createProject("main-in-run");
+	}
+
+	@Test
+	public void buildFromRunTask() {
+		project.newBuild().forTasks("build").withArguments("-PbootVersion=" + BOOT_VERSION, "--info").run();
+	}
+
+}