test for verify exception msg with empty src file

Author: lgh

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterRpc.java

@@ -1163,6 +1163,21 @@ public void testProxyGetPreferedBlockSize() throws Exception {
         routerProtocol, nnProtocol, m, new Object[] {badPath});
   }
 
+  private void testConcat(
+      String source, String target, boolean failureExpected, boolean verfiyException, String msg) {
+    boolean failure = false;
+    try {
+      // Concat test file with fill block length file via router
+      routerProtocol.concat(target, new String[] {source});
+    } catch (IOException ex) {
+      failure = true;
+      if (verfiyException) {
+        assertExceptionContains(msg, ex);
+      }
+    }
+    assertEquals(failureExpected, failure);
+  }
+
   private void testConcat(
       String source, String target, boolean failureExpected) {
     boolean failure = false;
@@ -1242,7 +1257,8 @@ public void testProxyConcatFile() throws Exception {
     String targetFile = cluster.getFederatedTestDirectoryForNS(sameNameservice) + "_targetFile";
     createFile(routerFS, targetFile, existingFileSize);
     // Concat in same namespaces, succeeds
-    testConcat(srcEmptyFile, targetFile, true);
+    testConcat(srcEmptyFile, targetFile, true, true,
+        "concat: source file " + srcEmptyFile + " is invalid or empty or underConstruction");
   }
 
   @Test