YARN-10336. RM page should throw exception when command injected in RM REST API to get applications. Contributed by Bilwa S T.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/AppsBlock.java

@@ -136,8 +136,7 @@ public class AppsBlock extends HtmlBlock {
 
     try {
       fetchData();
-    }
-    catch( Exception e) {
+    } catch (YarnException | IOException | InterruptedException e) {
       String message = "Failed to read the applications.";
       LOG.error(message, e);
       html.p().__(message).__();

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/test/java/org/apache/hadoop/yarn/server/webapp/TestAppsBlock.java

@@ -0,0 +1,76 @@
+/**
+ * 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.yarn.server.webapp;
+
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.commons.io.output.ByteArrayOutputStream;
+import org.apache.hadoop.yarn.webapp.SubView;
+import org.apache.hadoop.yarn.webapp.YarnWebParams;
+import org.apache.hadoop.yarn.webapp.view.BlockForTest;
+import org.apache.hadoop.yarn.webapp.view.HtmlBlock;
+import org.apache.hadoop.yarn.webapp.view.HtmlBlockForTest;
+import org.junit.Test;
+
+public class TestAppsBlock {
+
+  /**
+   * Test invalid application state.Exception should be thrown if application
+   * state is not valid.
+   */
+  @Test(expected = IllegalArgumentException.class)
+  public void testInvalidAppState() {
+    AppsBlock appBlock = new AppsBlock(null, null) {
+      // override this so that apps block can fetch app state.
+      @Override
+      public Map<String, String> moreParams() {
+        Map<String, String> map = new HashMap<>();
+        map.put(YarnWebParams.APP_STATE, "ACCEPTEDPING");
+        return map;
+      }
+
+      @Override
+      protected void renderData(Block html) {
+      }
+    };
+
+    // set up the test block to render AppsBlock
+    OutputStream outputStream = new ByteArrayOutputStream();
+    HtmlBlock.Block block = createBlockToCreateTo(outputStream);
+
+    // If application state is invalid it should throw exception
+    // instead of catching it.
+    appBlock.render(block);
+  }
+
+  private static HtmlBlock.Block createBlockToCreateTo(
+      OutputStream outputStream) {
+    PrintWriter printWriter = new PrintWriter(outputStream);
+    HtmlBlock html = new HtmlBlockForTest();
+    return new BlockForTest(html, printWriter, 10, false) {
+      @Override
+      protected void subView(Class<? extends SubView> cls) {
+      }
+    };
+  };
+
+}