Unit tests for NetworkCongifLinksProvider

Also fixed a few bugs in the provider that were turned up by the new tests.

Change-Id: Icafc945251b4d35ac3f285302af150c0a4d646d6
diff --git a/core/api/src/test/java/org/onosproject/net/link/LinkProviderRegistryAdapter.java b/core/api/src/test/java/org/onosproject/net/link/LinkProviderRegistryAdapter.java
new file mode 100644
index 0000000..00cb58b
--- /dev/null
+++ b/core/api/src/test/java/org/onosproject/net/link/LinkProviderRegistryAdapter.java
@@ -0,0 +1,49 @@
+/*
+ * 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.net.link;
+
+import java.util.Set;
+
+import org.onosproject.net.provider.ProviderId;
+
+import com.google.common.collect.ImmutableSet;
+
+/**
+ * Testing adapter for the LinkProviderRegistry API.
+ */
+public class LinkProviderRegistryAdapter implements LinkProviderRegistry {
+
+    LinkProviderServiceAdapter providerService = null;
+
+    @Override
+    public LinkProviderService register(LinkProvider provider) {
+        providerService = new LinkProviderServiceAdapter(provider);
+        return providerService;
+    }
+
+    @Override
+    public void unregister(LinkProvider provider) {
+    }
+
+    @Override
+    public Set<ProviderId> getProviders() {
+        return ImmutableSet.of(providerService.provider().id());
+    }
+
+    public LinkProviderServiceAdapter registeredProvider() {
+        return providerService;
+    }
+}