Fix `domain describe` reference (#1477)

* Fix domain describe reference

* Add unit test coverage

pkg/kn/commands/domain/describe.go

@@ -88,7 +88,14 @@ func describe(w io.Writer, domainMapping *v1alpha1.DomainMapping, printDetails b
 	commands.WriteMetadata(dw, &domainMapping.ObjectMeta, printDetails)
 	dw.WriteLine()
 	dw.WriteAttribute("URL", domainMapping.Status.URL.String())
-	dw.WriteAttribute("Service", domainMapping.Spec.Ref.Name)
+	dw.WriteLine()
+	ref := dw.WriteAttribute("Reference", "")
+	ref.WriteAttribute("APIVersion", domainMapping.Spec.Ref.APIVersion)
+	ref.WriteAttribute("Kind", domainMapping.Spec.Ref.Kind)
+	ref.WriteAttribute("Name", domainMapping.Spec.Ref.Name)
+	if domainMapping.Namespace != domainMapping.Spec.Ref.Namespace {
+		ref.WriteAttribute("Namespace", domainMapping.Spec.Ref.Namespace)
+	}
 	dw.WriteLine()
 	commands.WriteConditions(dw, domainMapping.Status.Conditions, printDetails)
 	if err := dw.Flush(); err != nil {

pkg/kn/commands/domain/describe_test.go

@@ -42,6 +42,9 @@ func TestDomainMappingDescribe(t *testing.T) {
 	assert.Assert(t, cmp.Regexp("Name:\\s+foo.bar", out))
 	assert.Assert(t, cmp.Regexp("Namespace:\\s+default", out))
 	assert.Assert(t, util.ContainsAll(out, "URL:", "http://foo.bar"))
+	assert.Assert(t, cmp.Regexp("Reference:", out))
+	assert.Assert(t, cmp.Regexp("Kind:\\s+Service", out))
+	assert.Assert(t, cmp.Regexp("Name:\\s+foo", out))
 	assert.Assert(t, util.ContainsAll(out, "Conditions:", "Ready"))
 
 	// There're 2 empty lines used in the "describe" formatting
@@ -51,7 +54,27 @@ func TestDomainMappingDescribe(t *testing.T) {
 			lineCounter++
 		}
 	}
-	assert.Equal(t, lineCounter, 2)
+	assert.Equal(t, lineCounter, 3)
+
+	servingRecorder.Validate()
+}
+
+func TestDomainMappingDescribeDiffNamespace(t *testing.T) {
+	client := v1alpha1.NewMockKnServiceClient(t)
+
+	servingRecorder := client.Recorder()
+	servingRecorder.GetDomainMapping("foo.bar", getDomainMapping("otherNS"), nil)
+
+	out, err := executeDomainCommand(client, nil, "describe", "foo.bar")
+	assert.NilError(t, err)
+	assert.Assert(t, cmp.Regexp("Name:\\s+foo.bar", out))
+	assert.Assert(t, cmp.Regexp("Namespace:\\s+default", out))
+	assert.Assert(t, util.ContainsAll(out, "URL:", "http://foo.bar"))
+	assert.Assert(t, cmp.Regexp("Reference:", out))
+	assert.Assert(t, cmp.Regexp("Kind:\\s+Service", out))
+	assert.Assert(t, cmp.Regexp("Name:\\s+foo", out))
+	assert.Assert(t, cmp.Regexp("Namespace:\\s+otherNS", out))
+	assert.Assert(t, util.ContainsAll(out, "Conditions:", "Ready"))
 
 	servingRecorder.Validate()
 }
@@ -68,6 +91,24 @@ func TestDomainMappingDescribeError(t *testing.T) {
 	servingRecorder.Validate()
 }
 
+func TestDomainMappingDescribeNameError(t *testing.T) {
+	client := v1alpha1.NewMockKnServiceClient(t)
+
+	servingRecorder := client.Recorder()
+
+	_, err := executeDomainCommand(client, nil, "describe")
+	assert.Assert(t, err != nil)
+	assert.Assert(t, util.ContainsAll(err.Error(), "name", "single", "argument"))
+
+	servingRecorder.Validate()
+
+	_, err = executeDomainCommand(client, nil, "describe", "foo", "bar")
+	assert.Assert(t, err != nil)
+	assert.Assert(t, util.ContainsAll(err.Error(), "name", "single", "argument"))
+
+	servingRecorder.Validate()
+}
+
 func TestDomainMappingDescribeURL(t *testing.T) {
 	client := v1alpha1.NewMockKnServiceClient(t)
 
@@ -94,11 +135,15 @@ func TestDomainMappingDescribeYAML(t *testing.T) {
 	servingRecorder.Validate()
 }
 
-func getDomainMapping() *servingv1alpha1.DomainMapping {
-	dm := createDomainMapping("foo.bar", createServiceRef("foo", "default"), "")
+func getDomainMapping(ns ...string) *servingv1alpha1.DomainMapping {
+	serviceNamespace := "default"
+	if len(ns) == 1 {
+		serviceNamespace = ns[0]
+	}
+	dm := createDomainMapping("foo.bar", createServiceRef("foo", serviceNamespace), "")
 	dm.TypeMeta = v1.TypeMeta{
 		Kind:       "DomainMapping",
-		APIVersion: "serving.knative.dev/v1alpha1",
+		APIVersion: servingv1alpha1.SchemeGroupVersion.String(),
 	}
 	dm.Status = servingv1alpha1.DomainMappingStatus{
 		Status: duckv1.Status{