fix: fix non-boolean being returned for null/undefined values

Refactored tests a bit.

Author: satazor

index.js

@@ -24,7 +24,7 @@ function withIs(Class, { className, symbolName }) {
         },
     }[className];
 
-    ClassIsWrapper[`is${className}`] = (obj) => obj && Boolean(obj[symbol]);
+    ClassIsWrapper[`is${className}`] = (obj) => !!(obj && obj[symbol]);
 
     return ClassIsWrapper;
 }
@@ -51,7 +51,7 @@ function withIsProto(Class, { className, symbolName }) {
         },
     });
 
-    ClassIsWrapper[`is${className}`] = (obj) => obj && Boolean(obj[symbol]);
+    ClassIsWrapper[`is${className}`] = (obj) => !!(obj && obj[symbol]);
 
     return ClassIsWrapper;
 }

test/es5.test.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const withIs = require('..');
+
+const Circle = withIs.proto(function () {
+    if (!(this instanceof Circle)) { // eslint-disable-line no-invalid-this
+        return new Circle();
+    }
+}, { className: 'Circle', symbolName: '@org/package/circle' });
+
+const Square = withIs.proto(function () {
+    if (!(this instanceof Square)) { // eslint-disable-line no-invalid-this
+        return new Square();
+    }
+}, { className: 'Square', symbolName: '@org/package/square' });
+
+const circle = new Circle();
+const square = new Square();
+
+test('circle is an instance of Circle class', () => {
+    expect(Circle.isCircle(circle)).toBe(true);
+});
+
+test('square is not an instance of Circle class', () => {
+    expect(Circle.isCircle(square)).toBe(false);
+});
+
+test('square is an instance of Square class', () => {
+    expect(Square.isSquare(square)).toBe(true);
+});
+
+test('circle is not an instance of Square class', () => {
+    expect(Square.isSquare(circle)).toBe(false);
+});
+
+test('calling without new', () => {
+    const circle = Circle(); // eslint-disable-line new-cap
+
+    expect(Circle.isCircle(circle)).toBe(true);
+});
+
+test('undefined/null is not an instance of any class', () => {
+    expect(Circle.isCircle(undefined)).toBe(false);
+    expect(Circle.isCircle(null)).toBe(false);
+});
+
+test('check custom tag of Square class', () => {
+    expect(Object.prototype.toString.call(square)).toBe('[object Square]');
+});

test/es6.test.js

@@ -0,0 +1,45 @@
+'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);
+});
+
+test('wolf is not an instance of Person class', () => {
+    expect(Person.isPerson(wolf)).toBe(false);
+});
+
+test('wolf is an instance of Animal class', () => {
+    expect(Animal.isAnimal(wolf)).toBe(true);
+});
+
+test('person is not an instance of Animal class', () => {
+    expect(Animal.isAnimal(diogo)).toBe(false);
+});
+
+test('undefined/null is not an instance of any class', () => {
+    expect(Person.isPerson(undefined)).toBe(false);
+    expect(Person.isPerson(null)).toBe(false);
+});
+
+test('check custom tag of class', () => {
+    expect(Object.prototype.toString.call(diogo)).toBe('[object Person]');
+    expect(Object.prototype.toString.call(wolf)).toBe('[object Animal]');
+});