[ONOS-3880, 3881] Yang Listener for Module and Sub-Module

Change-Id: Iee75c3e04af9b66ebc38acb3396aa4c54af5a268
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListenerTest.java
new file mode 100644
index 0000000..f2415b2
--- /dev/null
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/BaseFileListenerTest.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * 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.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/**
+ * Test cases for testing base rule listener functionality.
+ */
+public class BaseFileListenerTest {
+
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    /**
+     * Checks for exception if stack of parsable data is not empty at the entry
+     * of yang base rule.
+     */
+    @Test
+    public void processYangFileEntryNonEmptyStack() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Invalid holder for yangbase before processing.");
+
+        YangModule tmpModule = new YangModule();
+        TreeWalkListener listener = new TreeWalkListener();
+        listener.getParsedDataStack().push(tmpModule);
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that exception shouldn't be generated if stack of parsable data is
+     * empty at the entry of yang base rule.
+     */
+    @Test
+    public void processYangFileEntryEmptyStack() {
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that exception should be generated if stack of parsable data is
+     * not empty at the exit of yang base rule.
+     */
+    @Test
+    public void processYangFileExitEmptyStack() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Missing holder at yangbase after processing.");
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileExit(listener, ctx);
+    }
+
+    /**
+     * Checks that exception shouldn't be generated if stack of parsable data is
+     * empty at the exit of yang base rule.
+     */
+    @Test
+    public void processYangFileExitNonEmptyStack() {
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that after popping out the parsable node from stack it should be
+     * empty.
+     */
+    @Test
+    public void processYangFileExitStackErrorExtraEntryTest() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Invalid holder for yangbase after processing.");
+
+        YangModule tmpModule = new YangModule();
+        YangModule tmpModule2 = new YangModule();
+        TreeWalkListener listener = new TreeWalkListener();
+        listener.getParsedDataStack().push(tmpModule);
+        listener.getParsedDataStack().push(tmpModule2);
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileExit(listener, ctx);
+    }
+}
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