feat: add withoutNew option

Also fix a bug where the proto inheritance chain was not setup properly.
Refactored tests to their own files and improved the overall test suite.

Author: satazor

README.md

@@ -50,7 +50,10 @@ class Person {
     }
 }
 
-module.exports = withIs(Person, { className: 'Person', symbolName: '@org/package-x/person' });
+module.exports = withIs(Person, {
+    className: 'Person',
+    symbolName: '@org/package-x/Person',
+});
 ```
 
 ```js
@@ -63,7 +66,10 @@ class Animal {
     }
 }
 
-module.exports = withIs(Animal, { className: 'Animal', symbolName: '@org/package-y/animal' });
+module.exports = withIs(Animal, {
+    className: 'Animal',
+    symbolName: '@org/package-y/Animal',
+});
 ```
 
 ```js
@@ -93,6 +99,8 @@ function Circle(radius) {
     if (!(this instanceof Circle)) {
         return new Circle();
     }
+
+    this.radius = radius;
 }
 ```
 
@@ -101,26 +109,38 @@ In such cases you can use the `withIs.proto` method:
 ```js
 const withIs = require('class-is');
 
-const Circle = withIs.proto(function () {
+const Circle = withIs.proto(function (radius) {
     if (!(this instanceof Circle)) {
         return new Circle();
     }
-}, { className: 'Circle', symbolName: '@org/package/circle' });
-
-const circle = Circle();
 
-console.log(Circle.isCircle(circle));
+    this.radius = radius;
+}, {
+    className: 'Circle',
+    symbolName: '@org/package/Circle',
+});
 ```
 
-The example above will print:
-```
-true
+...or even better:
+
+```js
+const withIs = require('class-is');
+
+function Circle(radius) {
+    this.radius = radius;
+}
+
+module.exports = withIs.proto(Circle, {
+    className: 'Circle',
+    symbolName: '@org/package/Circle',
+    withoutNew: true,
+});
 ```
 
 
 ## API
 
-### withIs(Class, { className: name, symbolName: symbol })
+### withIs(Class, { className, symbolName })
 
 ###### class
 
@@ -140,11 +160,18 @@ Type: `String`
 
 Unique *id* for the class. This should be namespaced so different classes from different modules do not collide and give false positives.
 
-Example: `@organization/package/class`
+Example: `@organization/package/Class`
+
+### withIs.proto(Class, { className, symbolName, withoutNew })
+
+The `className` and `symbolName` parameters are the same as above.
+
+###### withoutNew
 
-### withIs.proto(Class, { className: name, symbolName: symbol })
+Type: `Boolean`   
+Default: `false`
 
-Apply the same parameters as above.
+Allow creating an instance without the `new` operator.
 
 
 ## Tests

index.js

@@ -27,12 +27,16 @@ function withIs(Class, { className, symbolName }) {
     return ClassIsWrapper;
 }
 
-function withIsProto(Class, { className, symbolName }) {
+function withIsProto(Class, { className, symbolName, withoutNew }) {
     const symbol = Symbol.for(symbolName);
 
+    /* eslint-disable object-shorthand */
     const ClassIsWrapper = {
-        /* eslint-disable object-shorthand */
         [className]: function (...args) {
+            if (withoutNew && !(this instanceof ClassIsWrapper)) {
+                return new ClassIsWrapper(...args);
+            }
+
             const _this = Class.call(this, ...args) || this;
 
             if (_this && !_this[symbol]) {
@@ -42,6 +46,10 @@ function withIsProto(Class, { className, symbolName }) {
             return _this;
         },
     }[className];
+    /* eslint-enable object-shorthand */
+
+    ClassIsWrapper.prototype = Object.create(Class.prototype);
+    ClassIsWrapper.prototype.constructor = ClassIsWrapper;
 
     Object.defineProperty(ClassIsWrapper.prototype, Symbol.toStringTag, {
         get() {

test/es5.test.js

@@ -1,49 +1,127 @@
 'use strict';
 
-const withIs = require('..');
+const {
+    Animal,
+    Plant,
+    Mammal,
+    Algae,
 
-const Circle = withIs.proto(function () {
-    if (!(this instanceof Circle)) { // eslint-disable-line no-invalid-this
-        return new Circle();
-    }
-}, { className: 'Circle', symbolName: '@org/package/circle' });
+    ExplicitWithoutNew,
+    ImplicitWithoutNew,
+    ImplicitExplicitWithoutNew,
+} = require('./fixtures/es5');
 
-const Square = withIs.proto(function () {
-    if (!(this instanceof Square)) { // eslint-disable-line no-invalid-this
-        return new Square();
-    }
-}, { className: 'Square', symbolName: '@org/package/square' });
+it('should setup the prototype chain correctly', () => {
+    const animal = new Animal('mammal');
+    const plant = new Plant('algae');
 
-const circle = new Circle();
-const square = new Square();
+    expect(Object.getPrototypeOf(animal)).toBe(Animal.prototype);
+    expect(Object.getPrototypeOf(Object.getPrototypeOf(animal))).toBe(Animal.WrappedClass.prototype);
+    expect(Object.getPrototypeOf(animal)).not.toBe(Plant.prototype);
+    expect(Object.getPrototypeOf(plant)).toBe(Plant.prototype);
+    expect(Object.getPrototypeOf(Object.getPrototypeOf(plant))).toBe(Plant.WrappedClass.prototype);
+    expect(Object.getPrototypeOf(plant)).not.toBe(Animal.prototype);
 
-test('circle is an instance of Circle class', () => {
-    expect(Circle.isCircle(circle)).toBe(true);
-});
+    expect(animal instanceof Animal).toBe(true);
+    expect(animal instanceof Animal.WrappedClass).toBe(true);
+    expect(animal instanceof Plant).toBe(false);
+    expect(plant instanceof Plant).toBe(true);
+    expect(plant instanceof Plant.WrappedClass).toBe(true);
+    expect(plant instanceof Animal).toBe(false);
 
-test('square is not an instance of Circle class', () => {
-    expect(Circle.isCircle(square)).toBe(false);
+    expect(animal.getType()).toBe('mammal');
+    expect(plant.getType()).toBe('algae');
 });
 
-test('square is an instance of Square class', () => {
-    expect(Square.isSquare(square)).toBe(true);
+it('should have a custom toStringTag', () => {
+    expect(Object.prototype.toString.call(new Animal())).toBe('[object Animal]');
+    expect(Object.prototype.toString.call(new Plant())).toBe('[object Plant]');
 });
 
-test('circle is not an instance of Square class', () => {
-    expect(Square.isSquare(circle)).toBe(false);
-});
+describe('is<className> method', () => {
+    it('should add a working is<className> static method', () => {
+        const animal = new Animal('mammal');
+        const plant = new Plant('algae');
 
-test('calling without new', () => {
-    const circle = Circle(); // eslint-disable-line new-cap
+        expect(Animal.isAnimal(animal)).toBe(true);
+        expect(Animal.isAnimal(plant)).toBe(false);
+        expect(Plant.isPlant(plant)).toBe(true);
+        expect(Plant.isPlant(animal)).toBe(false);
+    });
 
-    expect(Circle.isCircle(circle)).toBe(true);
-});
+    it('should not crash if `null` or `undefined` is passed to is<ClassName>', () => {
+        expect(Animal.isAnimal(null)).toBe(false);
+        expect(Animal.isAnimal(undefined)).toBe(false);
+    });
+
+    it('should work correctly for deep inheritance scenarios', () => {
+        const mammal = new Mammal();
+        const algae = new Algae();
 
-test('undefined/null is not an instance of any class', () => {
-    expect(Circle.isCircle(undefined)).toBe(false);
-    expect(Circle.isCircle(null)).toBe(false);
+        expect(Mammal.isMammal(mammal)).toBe(true);
+        expect(Animal.isAnimal(mammal)).toBe(true);
+        expect(Mammal.isMammal(algae)).toBe(false);
+        expect(Animal.isAnimal(algae)).toBe(false);
+
+        expect(Algae.isAlgae(algae)).toBe(true);
+        expect(Plant.isPlant(algae)).toBe(true);
+        expect(Algae.isAlgae(mammal)).toBe(false);
+        expect(Plant.isPlant(mammal)).toBe(false);
+    });
 });
 
-test('check custom tag of Square class', () => {
-    expect(Object.prototype.toString.call(square)).toBe('[object Square]');
+describe('new operator', () => {
+    it('should work on explicit without-new handling', () => {
+        const instance = new ExplicitWithoutNew();
+        const instance2 = ExplicitWithoutNew(); // eslint-disable-line new-cap
+
+        expect(Object.getPrototypeOf(instance)).toBe(ExplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instance))).toBe(ExplicitWithoutNew.WrappedClass.prototype);
+        expect(Object.getPrototypeOf(instance2)).toBe(ExplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instance2))).toBe(ExplicitWithoutNew.WrappedClass.prototype);
+
+        expect(instance instanceof ExplicitWithoutNew).toBe(true);
+        expect(instance instanceof ExplicitWithoutNew.WrappedClass).toBe(true);
+        expect(instance2 instanceof ExplicitWithoutNew).toBe(true);
+        expect(instance2 instanceof ExplicitWithoutNew.WrappedClass).toBe(true);
+
+        expect(instance.getLabel()).toBe('ExplicitWithoutNew');
+        expect(instance2.getLabel()).toBe('ExplicitWithoutNew');
+    });
+
+    it('should work on implicit without-new handling', () => {
+        const instance = new ImplicitWithoutNew();
+        const instanceNoNew = ImplicitWithoutNew(); // eslint-disable-line new-cap
+
+        expect(Object.getPrototypeOf(instance)).toBe(ImplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instance))).toBe(ImplicitWithoutNew.WrappedClass.prototype);
+        expect(Object.getPrototypeOf(instanceNoNew)).toBe(ImplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instanceNoNew))).toBe(ImplicitWithoutNew.WrappedClass.prototype);
+
+        expect(instance instanceof ImplicitWithoutNew).toBe(true);
+        expect(instance instanceof ImplicitWithoutNew.WrappedClass).toBe(true);
+        expect(instanceNoNew instanceof ImplicitWithoutNew).toBe(true);
+        expect(instanceNoNew instanceof ImplicitWithoutNew.WrappedClass).toBe(true);
+
+        expect(instance.getLabel()).toBe('ImplicitWithoutNew');
+        expect(instanceNoNew.getLabel()).toBe('ImplicitWithoutNew');
+    });
+
+    it('should work on explicit & implicit without-new handling', () => {
+        const instance = new ImplicitExplicitWithoutNew();
+        const instanceNoNew = ImplicitExplicitWithoutNew(); // eslint-disable-line new-cap
+
+        expect(Object.getPrototypeOf(instance)).toBe(ImplicitExplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instance))).toBe(ImplicitExplicitWithoutNew.WrappedClass.prototype);
+        expect(Object.getPrototypeOf(instanceNoNew)).toBe(ImplicitExplicitWithoutNew.prototype);
+        expect(Object.getPrototypeOf(Object.getPrototypeOf(instanceNoNew))).toBe(ImplicitExplicitWithoutNew.WrappedClass.prototype);
+
+        expect(instance instanceof ImplicitExplicitWithoutNew).toBe(true);
+        expect(instance instanceof ImplicitExplicitWithoutNew.WrappedClass).toBe(true);
+        expect(instanceNoNew instanceof ImplicitExplicitWithoutNew).toBe(true);
+        expect(instanceNoNew instanceof ImplicitExplicitWithoutNew.WrappedClass).toBe(true);
+
+        expect(instance.getLabel()).toBe('ImplicitExplicitWithoutNew');
+        expect(instanceNoNew.getLabel()).toBe('ImplicitExplicitWithoutNew');
+    });
 });

test/es6.test.js

@@ -1,45 +1,67 @@
 'use strict';
 
-const withIs = require('..');
-
-const Person = withIs(class {
-    constructor(name, city) {
-        this.name = name;
-        this.city = city;
-    }
-}, { className: 'Person', symbolName: '@org/package-x/person' });
-
-const Animal = withIs(class {
-    constructor(species) {
-        this.species = species;
-    }
-}, { className: 'Animal', symbolName: '@org/package-y/person' });
-
-const diogo = new Person('Diogo', 'Porto');
-const wolf = new Animal('Wolf');
-
-test('person is an instance of Person class', () => {
-    expect(Person.isPerson(diogo)).toBe(true);
-});
+const {
+    Animal,
+    Plant,
+    Mammal,
+    Algae,
+} = require('./fixtures/es6');
 
-test('wolf is not an instance of Person class', () => {
-    expect(Person.isPerson(wolf)).toBe(false);
-});
+it('should setup the prototype chain correctly', () => {
+    const animal = new Animal('mammal');
+    const plant = new Plant('algae');
 
-test('wolf is an instance of Animal class', () => {
-    expect(Animal.isAnimal(wolf)).toBe(true);
-});
+    expect(Object.getPrototypeOf(animal)).toBe(Animal.prototype);
+    expect(Object.getPrototypeOf(Object.getPrototypeOf(animal))).toBe(Animal.WrappedClass.prototype);
+    expect(Object.getPrototypeOf(animal)).not.toBe(Plant.prototype);
+    expect(Object.getPrototypeOf(plant)).toBe(Plant.prototype);
+    expect(Object.getPrototypeOf(Object.getPrototypeOf(plant))).toBe(Plant.WrappedClass.prototype);
+    expect(Object.getPrototypeOf(plant)).not.toBe(Animal.prototype);
 
-test('person is not an instance of Animal class', () => {
-    expect(Animal.isAnimal(diogo)).toBe(false);
+    expect(animal instanceof Animal).toBe(true);
+    expect(animal instanceof Animal.WrappedClass).toBe(true);
+    expect(animal instanceof Plant).toBe(false);
+    expect(plant instanceof Plant).toBe(true);
+    expect(plant instanceof Plant.WrappedClass).toBe(true);
+    expect(plant instanceof Animal).toBe(false);
+
+    expect(animal.getType()).toBe('mammal');
+    expect(plant.getType()).toBe('algae');
 });
 
-test('undefined/null is not an instance of any class', () => {
-    expect(Person.isPerson(undefined)).toBe(false);
-    expect(Person.isPerson(null)).toBe(false);
+it('should have a custom toStringTag', () => {
+    expect(Object.prototype.toString.call(new Animal())).toBe('[object Animal]');
+    expect(Object.prototype.toString.call(new Plant())).toBe('[object Plant]');
 });
 
-test('check custom tag of class', () => {
-    expect(Object.prototype.toString.call(diogo)).toBe('[object Person]');
-    expect(Object.prototype.toString.call(wolf)).toBe('[object Animal]');
+describe('is<className> method', () => {
+    it('should add a working is<className> static method', () => {
+        const animal = new Animal('mammal');
+        const plant = new Plant('algae');
+
+        expect(Animal.isAnimal(animal)).toBe(true);
+        expect(Animal.isAnimal(plant)).toBe(false);
+        expect(Plant.isPlant(plant)).toBe(true);
+        expect(Plant.isPlant(animal)).toBe(false);
+    });
+
+    it('should not crash if `null` or `undefined` is passed to is<ClassName>', () => {
+        expect(Animal.isAnimal(null)).toBe(false);
+        expect(Animal.isAnimal(undefined)).toBe(false);
+    });
+
+    it('should work correctly for deep inheritance scenarios', () => {
+        const mammal = new Mammal();
+        const algae = new Algae();
+
+        expect(Mammal.isMammal(mammal)).toBe(true);
+        expect(Animal.isAnimal(mammal)).toBe(true);
+        expect(Mammal.isMammal(algae)).toBe(false);
+        expect(Animal.isAnimal(algae)).toBe(false);
+
+        expect(Algae.isAlgae(algae)).toBe(true);
+        expect(Plant.isPlant(algae)).toBe(true);
+        expect(Algae.isAlgae(mammal)).toBe(false);
+        expect(Plant.isPlant(mammal)).toBe(false);
+    });
 });