SEBA-688 add additional unit tests

Change-Id: I361bc872af08b97bccb29f17838940205fed48e9
diff --git a/commands/modeltypes_test.go b/commands/modeltypes_test.go
new file mode 100644
index 0000000..678afba
--- /dev/null
+++ b/commands/modeltypes_test.go
@@ -0,0 +1,110 @@
+/*
+ * Portions copyright 2019-present Open Networking Foundation
+ * Original copyright 2019-present Ciena Corporation
+ *
+ * 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 commands
+
+import (
+	"bytes"
+	"github.com/opencord/cordctl/testutils"
+	"testing"
+)
+
+func TestModelTypeList(t *testing.T) {
+	// use `python -m json.tool` to pretty-print json
+	expected := `AddressPool
+AttWorkflowDriverService
+AttWorkflowDriverServiceInstance
+AttWorkflowDriverWhiteListEntry
+BNGPortMapping
+BackupFile
+BackupOperation
+BandwidthProfile
+ComputeServiceInstance
+FabricCrossconnectService
+FabricCrossconnectServiceInstance
+FabricIpAddress
+FabricService
+Flavor
+Image
+InterfaceType
+KubernetesConfigMap
+KubernetesConfigVolumeMount
+KubernetesData
+KubernetesResourceInstance
+KubernetesSecret
+KubernetesSecretVolumeMount
+KubernetesService
+KubernetesServiceInstance
+NNIPort
+Network
+NetworkParameter
+NetworkParameterType
+NetworkSlice
+NetworkTemplate
+Node
+NodeLabel
+NodeToSwitchPort
+OLTDevice
+ONOSApp
+ONOSService
+ONUDevice
+PONONUPort
+PONPort
+Port
+PortBase
+PortInterface
+Principal
+Privilege
+RCORDIpAddress
+RCORDService
+RCORDSubscriber
+Role
+Service
+ServiceAttribute
+ServiceDependency
+ServiceGraphConstraint
+ServiceInstance
+ServiceInstanceAttribute
+ServiceInstanceLink
+ServiceInterface
+ServicePort
+Site
+Slice
+Switch
+SwitchPort
+Tag
+TrustDomain
+UNIPort
+User
+VOLTService
+VOLTServiceInstance
+XOSCore
+XOSGuiExtension
+`
+
+	got := new(bytes.Buffer)
+	OutputStream = got
+
+	var options ModelTypeOpts
+	err := options.List.Execute([]string{})
+
+	if err != nil {
+		t.Errorf("%s: Received error %v", t.Name(), err)
+		return
+	}
+
+	testutils.AssertStringEqual(t, got.String(), expected)
+}