Implement basic unit tests for RouteHandler

In addition,
    - Refactor Segment Routing unit test mocking

Change-Id: I94cb75a8b12944264faa76301d58ee19f246d584
diff --git a/src/test/java/org/onosproject/segmentrouting/MockNetworkConfigRegistry.java b/src/test/java/org/onosproject/segmentrouting/MockNetworkConfigRegistry.java
new file mode 100644
index 0000000..09f8da2
--- /dev/null
+++ b/src/test/java/org/onosproject/segmentrouting/MockNetworkConfigRegistry.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * 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.segmentrouting;
+
+import com.google.common.collect.Sets;
+import org.onosproject.net.config.Config;
+import org.onosproject.net.config.NetworkConfigRegistryAdapter;
+
+import java.util.Set;
+
+/**
+ * Mock Network Config Registry.
+ */
+class MockNetworkConfigRegistry extends NetworkConfigRegistryAdapter {
+    private Set<Config> configs = Sets.newHashSet();
+
+    public void applyConfig(Config config) {
+        configs.add(config);
+    }
+
+    @Override
+    public <S, C extends Config<S>> C getConfig(S subject, Class<C> configClass) {
+        Config c = configs.stream()
+                .filter(config -> subject.equals(config.subject()))
+                .filter(config -> configClass.equals(config.getClass()))
+                .findFirst().orElse(null);
+        return (C) c;
+    }
+}
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