Add bootTestRun to run app using test source set output and classpath

Closes gh-35248

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/boottestrun/classpath/BootTestRunClasspathApplication.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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 com.example.boottestrun.classpath;
+
+import java.io.File;
+import java.lang.management.ManagementFactory;
+
+/**
+ * Application used for testing {@code bootTestRun}'s classpath handling.
+ *
+ * @author Andy Wilkinson
+ */
+public class BootTestRunClasspathApplication {
+
+	protected BootTestRunClasspathApplication() {
+
+	}
+
+	public static void main(String[] args) {
+		System.out.println("Main class name = " + BootTestRunClasspathApplication.class.getName());
+		int i = 1;
+		for (String entry : ManagementFactory.getRuntimeMXBean().getClassPath().split(File.pathSeparator)) {
+			System.out.println(i++ + ". " + entry);
+		}
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/boottestrun/jvmargs/BootTestRunJvmArgsApplication.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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 com.example.boottestrun.jvmargs;
+
+import java.lang.management.ManagementFactory;
+
+/**
+ * Application used for testing {@code bootTestRun}'s JVM argument handling.
+ *
+ * @author Andy Wilkinson
+ */
+public class BootTestRunJvmArgsApplication {
+
+	protected BootTestRunJvmArgsApplication() {
+
+	}
+
+	public static void main(String[] args) {
+		int i = 1;
+		for (String entry : ManagementFactory.getRuntimeMXBean().getInputArguments()) {
+			System.out.println(i++ + ". " + entry);
+		}
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/com/example/boottestrun/nomain/BootTestRunNoMain.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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 com.example.boottestrun.nomain;
+
+/**
+ * Application used for testing {@code bootTestRun}'s handling of no test main method
+ *
+ * @author Andy Wilkinson
+ */
+public class BootTestRunNoMain {
+
+}