Add support for registry-based type aliases

src/create-type.js

@@ -5,6 +5,7 @@ const mapObj = require("map-obj");
 
 const typeRules = require("./type-rules");
 const generateDescriptor = require("./generate-descriptor");
+const generateValidator = require("./generate-validator");
 const getSchemaKeys = require("./util/get-schema-keys");
 const nullMissingFields = require("./util/null-missing-fields");
 

src/generate-validator.js

@@ -72,13 +72,33 @@ module.exports = function generateValidator(rule, name = "<unknown>", registry)
 			}
 		};
 	} else if (rule._isCustomRegistryType) {
+		/* HACK: We performantly memoize the validator for a registry-stored alias, by storing it in the validator generation scope. */
+		let aliasValidator;
+
 		baseRule = function (value) {
 			/* FIXME: Better error when the type is unknown */
-			if (registry._types.get(rule._name)._validator.call(this, value) === true) {
-				return true;
+			let actualType = registry._types.get(rule._name);
+
+			if (actualType._isCustomType) {
+				if (actualType._validator.call(this, value) === true) {
+					return true;
+				} else {
+					return new errors.ValidationError(`Expected ${getValueType(rule)}, got ${getValueType(value)} instead`);
+				}
 			} else {
-				/* FIXME: Add support for registry rules to getValueType */
-				return new errors.ValidationError(`Expected ${getValueType(rule)}, got ${getValueType(value)} instead`);
+				if (aliasValidator == null) {
+					aliasValidator = generateValidator(actualType._alias, name, registry);
+				}
+
+				let validatorResult = aliasValidator.call(this, value);
+
+				if (validatorResult === true) {
+					return true;
+				} else {
+					// return new errors.ValidationError(`Expected ${getValueType(actualType._alias)}, got ${getValueType(value)} instead`);
+					/* FIXME: Possible this is done wrong elsewhere too, swallowing the actual validation error? */
+					return validatorResult;
+				}
 			}
 		};
 	} else if (rule._isTrait === true) {

test/registry.js

@@ -4,6 +4,8 @@ const expect = require("chai").expect;
 
 const dm = require("../src");
 
+/* FIXME: setOf/mapOf? */
+
 describe("registry", () => {
 	let registry = dm.createRegistry();
 
@@ -123,5 +125,25 @@ describe("registry", () => {
 				flowers.to = flowers;
 			}).to.throw("Expected an instance of Person, got an instance of Gift instead");
 		});
+
+		it("should work correctly for type aliases", () => {
+			let CheckedString = registry.createType("CheckedString", dm.string({ matches: /^[a-z]+$/ }));
+
+			let SomeType = registry.createType("SomeType", {
+				value: registry.type("CheckedString")
+			});
+
+			let instance = SomeType({
+				value: "foo"
+			});
+
+			expect(instance.value).to.equal("foo");
+
+			expect(() => {
+				SomeType({
+					value: "bar42"
+				});
+			}).to.throw("Value for property 'value' failed `matches` condition");
+		})
 	});
 });