Unit tests for Instruction and Ethernet codecs

Added tests for codecs for Ethernet and Instruction classes
Also fixed some bugs uncovered by the tests

Change-Id: I29f82d169e81b3fca417f88fab992148bf36dc71
diff --git a/web/api/src/test/java/org/onosproject/codec/impl/MockCodecContext.java b/web/api/src/test/java/org/onosproject/codec/impl/MockCodecContext.java
new file mode 100644
index 0000000..f54f523
--- /dev/null
+++ b/web/api/src/test/java/org/onosproject/codec/impl/MockCodecContext.java
@@ -0,0 +1,51 @@
+/*
+ * 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.codec.impl;
+
+import org.onosproject.codec.CodecContext;
+import org.onosproject.codec.JsonCodec;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * Mock codec context for use in codec unit tests.
+ */
+public final class MockCodecContext implements CodecContext {
+
+    private ObjectMapper mapper = new ObjectMapper();
+    private CodecManager manager = new CodecManager();
+
+    public MockCodecContext() {
+        manager.activate();
+    }
+
+    @Override
+    public ObjectMapper mapper() {
+        return mapper;
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public <T> JsonCodec<T> codec(Class<T> entityClass) {
+        return manager.getCodec(entityClass);
+    }
+
+    @Override
+    public <T> T get(Class<T> serviceClass) {
+        return null;
+    }
+
+}