[VOL-2235] Mocks and interfaces for rw-core

This update consists of mocks that are used by the rw-core
during unit testing.  It also includes interfaces used for unit
tests.

Change-Id: I20ca1455c358113c3aa897acc6355e0ddbc614b7
diff --git a/rw_core/mocks/adapter_onu_test.go b/rw_core/mocks/adapter_onu_test.go
new file mode 100644
index 0000000..748815a
--- /dev/null
+++ b/rw_core/mocks/adapter_onu_test.go
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2019-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 mocks
+
+import (
+	"github.com/opencord/voltha-lib-go/v2/pkg/adapters"
+	"testing"
+)
+
+func TestONUAdapterImplementsIAdapter(t *testing.T) {
+	adapter := NewONUAdapter(nil)
+
+	if _, ok := interface{}(adapter).(adapters.IAdapter); !ok {
+		t.Error("ONU adapter does not implement voltha-lib-go/v2/pkg/adapters/IAdapter interface")
+	}
+}