Test that exception is thrown when encountering non-static main

Author: cptaffe

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/NonStaticMain.java

@@ -0,0 +1,23 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.hadoop.util;
+
+public class NonStaticMain {
+    public void main(String[] args) {
+    }
+}

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestRunJar.java

@@ -297,4 +297,35 @@ public void testUnJar2() throws IOException {
           "would create file outside of", e);
     }
   }
-}
+
+  /**
+   * Tests that RunJar errors appropriately for classes with non-static main
+   * methods.
+   */
+  public void testRunNonStaticMain() throws Throwable {
+    RunJar runJar = spy(new RunJar());
+    // enable the client classloader
+    when(runJar.useClientClassLoader()).thenReturn(true);
+    // set the system classes and blacklist the test main class and the test
+    // third class so they can be loaded by the application classloader
+    String mainCls = NonStaticMain.class.getName();
+    String systemClasses = "-" + mainCls + "," + ApplicationClassLoader.SYSTEM_CLASSES_DEFAULT;
+    when(runJar.getSystemClasses()).thenReturn(systemClasses);
+
+    // create the test jar
+    File testJar = JarFinder.makeClassLoaderTestJar(this.getClass(), TEST_ROOT_DIR, TEST_JAR_2_NAME, BUFF_SIZE,
+        mainCls);
+    // form the args
+    String[] args = new String[3];
+    args[0] = testJar.getAbsolutePath();
+    args[1] = mainCls;
+
+    // run RunJar
+    try {
+      runJar.run(args);
+      fail("run should throw IOException.");
+    } catch (IOException e) {
+      GenericTestUtils.assertExceptionContains("Method main must be static", e);
+    }
+  }
+}