Add rid constructors

rid/resource_identifier.go

@@ -34,8 +34,31 @@ type ResourceIdentifier struct {
 	Locator string
 }
 
+const (
+	RidClass  = "ri"
+	Separator = "."
+)
+
+func MustNew(service, instance, resourceType, locator string) ResourceIdentifier {
+	resourceIdentifier, err := New(service, instance, resourceType, locator)
+	if err != nil {
+		panic(err)
+	}
+	return resourceIdentifier
+}
+
+func New(service, instance, resourceType, locator string) (ResourceIdentifier, error) {
+	resourceIdentifier := ResourceIdentifier{
+		Service:  service,
+		Instance: instance,
+		Type:     resourceType,
+		Locator:  locator,
+	}
+	return resourceIdentifier, resourceIdentifier.validate()
+}
+
 func (rid ResourceIdentifier) String() string {
-	return "ri." + rid.Service + "." + rid.Instance + "." + rid.Type + "." + rid.Locator
+	return RidClass + Separator + rid.Service + Separator + rid.Instance + Separator + rid.Type + Separator + rid.Locator
 }
 
 // MarshalText implements encoding.TextMarshaler (used by encoding/json and others).
@@ -56,8 +79,8 @@ func (rid *ResourceIdentifier) UnmarshalText(text []byte) error {
 
 // ParseRID parses a string into a 4-part resource identifier.
 func ParseRID(s string) (ResourceIdentifier, error) {
-	segments := strings.SplitN(s, ".", 5)
-	if len(segments) != 5 || segments[0] != "ri" {
+	segments := strings.SplitN(s, Separator, 5)
+	if len(segments) != 5 || segments[0] != RidClass {
 		return ResourceIdentifier{}, errors.New("invalid resource identifier")
 	}
 	rid := ResourceIdentifier{

rid/resource_identifier_test.go

@@ -52,6 +52,66 @@ func TestResourceIdentifier(t *testing.T) {
 			},
 			ExpectedErr: `rid first segment (service) does not match ^[a-z][a-z0-9\-]*$ pattern: rid second segment (instance) does not match ^([a-z0-9][a-z0-9\-]*)?$ pattern: rid third segment (type) does not match ^[a-z][a-z0-9\-]*$ pattern`,
 		},
+		{
+			Name: "service can't be empty",
+			Input: rid.ResourceIdentifier{
+				Service:  "",
+				Instance: "b",
+				Type:     "c",
+				Locator:  "d",
+			},
+			ExpectedErr: `rid first segment (service) does not match ^[a-z][a-z0-9\-]*$ pattern`,
+		},
+		{
+			Name: "service can't contain '.'",
+			Input: rid.ResourceIdentifier{
+				Service:  "a.a",
+				Instance: "b",
+				Type:     "c",
+				Locator:  "d",
+			},
+			ExpectedErr: `rid first segment (service) does not match ^[a-z][a-z0-9\-]*$ pattern`,
+		},
+		{
+			Name: "instance can't contain '.'",
+			Input: rid.ResourceIdentifier{
+				Service:  "a",
+				Instance: "b.b",
+				Type:     "c",
+				Locator:  "d",
+			},
+			ExpectedErr: `rid second segment (instance) does not match ^([a-z0-9][a-z0-9\-]*)?$ pattern`,
+		},
+		{
+			Name: "type can't be empty",
+			Input: rid.ResourceIdentifier{
+				Service:  "a",
+				Instance: "b",
+				Type:     "",
+				Locator:  "d",
+			},
+			ExpectedErr: `rid third segment (type) does not match ^[a-z][a-z0-9\-]*$ pattern`,
+		},
+		{
+			Name: "type can't contain '.'",
+			Input: rid.ResourceIdentifier{
+				Service:  "a",
+				Instance: "b",
+				Type:     "c.c",
+				Locator:  "d",
+			},
+			ExpectedErr: `rid third segment (type) does not match ^[a-z][a-z0-9\-]*$ pattern`,
+		},
+		{
+			Name: "locator can't be empty",
+			Input: rid.ResourceIdentifier{
+				Service:  "a",
+				Instance: "b",
+				Type:     "c",
+				Locator:  "",
+			},
+			ExpectedErr: `rid fourth segment (locator) does not match ^[a-zA-Z0-9\-\._]+$ pattern`,
+		},
 	} {
 		t.Run(test.Name, func(t *testing.T) {
 			type ridContainer struct {