Added unit tests for MapEvent class.

Change-Id: I3c1c8091da01fbeaabf66d68d7c6cc1f2c2a2455

+/*
+ * Copyright 2015 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.store.service;
+
+import com.google.common.testing.EqualsTester;
+import junit.framework.TestCase;
+import org.junit.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+/**
+ * MapEvent unit tests.
+ */
+public class MapEventTest extends TestCase {
+
+    private final Versioned<Integer> vStats = new Versioned<>(2, 1);
+
+    private final MapEvent<String, Integer> stats1 = new MapEvent<>("a", MapEvent.Type.INSERT, "1", vStats);
+
+    private final MapEvent<String, Integer> stats2 = new MapEvent<>("a", MapEvent.Type.REMOVE, "1", vStats);
+
+    private final MapEvent<String, Integer> stats3 = new MapEvent<>("a", MapEvent.Type.UPDATE, "1", vStats);
+
+    /**
+     * Tests the creation of the MapEvent object.
+     */
+    @Test
+    public void testConstruction() {
+        assertThat(stats1.name(), is("a"));
+        assertThat(stats1.type(), is(MapEvent.Type.INSERT));
+        assertThat(stats1.key(), is("1"));
+        assertThat(stats1.value(), is(vStats));
+    }
+
+    /**
+     * Tests the equals, hashCode and toString methods using Guava EqualsTester.
+     */
+    @Test
+    public void testEquals() {
+        new EqualsTester()
+                .addEqualityGroup(stats1, stats1)
+                .addEqualityGroup(stats2)
+                .addEqualityGroup(stats3)
+                .testEquals();
+    }
+
+}
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