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

Change-Id: Iee75c3e04af9b66ebc38acb3396aa4c54af5a268
diff --git a/src/test/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListenerTest.java b/src/test/java/org/onosproject/yangutils/parser/impl/listeners/PrefixListenerTest.java
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+/*
+ * 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.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing prefix listener functionality.
+ */
+public class PrefixListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if value of prefix is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixInvalidValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixInvalidValue.yang");
+    }
+
+    /**
+     * Checks if prefix listener updates the data model tree.
+     */
+    @Test
+    public void processPrefixValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getPrefix(), is("On"));
+    }
+
+    /**
+     * Checks that prefix should be present just once.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixDualEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixDualEntry.yang");
+    }
+
+    /**
+     * Checks if prefix syntax is followed.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixMissingValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixMissingValue.yang");
+    }
+
+    /**
+     * Checks that exception should be reported if prefix is missing.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixOrder.yang");
+    }
+}
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