added unit tests for isElse function

src/ifElse.test.js

@@ -1,9 +1,71 @@
 'use strict';
 
 describe('ifElse', () => {
-  // const { ifElse } = require('./ifElse');
+  const { ifElse } = require('./ifElse');
 
-  it('should ', () => {});
+  let truthyCondition, falsyCondition, first, second;
 
-  // write tests here
+  beforeAll(() => {
+    truthyCondition = jest.fn(() => true);
+    falsyCondition = jest.fn(() => false);
+
+    first = jest.fn(() => 'First');
+    second = jest.fn(() => 'Second');
+  });
+
+  afterEach(() => {
+    first.mockClear();
+    second.mockClear();
+    truthyCondition.mockClear();
+    falsyCondition.mockClear();
+  });
+
+  it('should be a function', () => {
+    expect(ifElse).toBeInstanceOf(Function);
+  });
+
+  it('should return nothing', () => {
+    expect(ifElse(truthyCondition, first, second)).toEqual(undefined);
+  });
+
+  it('should invoke first cb if truthy contidion', () => {
+    ifElse(truthyCondition, first, second);
+
+    expect(first).toHaveBeenCalled();
+  });
+
+  it('should invoke second cb if falsy condition', () => {
+    ifElse(falsyCondition, first, second);
+
+    expect(second).toHaveBeenCalled();
+  });
+
+  it('should invoke one of functions in any case', () => {
+    const randomCondition = jest.fn().mockReturnValue(!!(Math.random() > 0.5));
+
+    ifElse(randomCondition, first, second);
+
+    const totalCalls = first.mock.calls.length + second.mock.calls.length;
+
+    expect(totalCalls).toBe(1);
+  });
+
+  it('should not work without condition', () => {
+    expect(() => {
+      ifElse(undefined, first, second);
+    }).toThrow();
+  });
+
+  it('should invoke first or second functions without args', () => {
+    ifElse(truthyCondition, first, second);
+    expect(first).toHaveBeenCalledWith();
+
+    ifElse(falsyCondition, first, second);
+    expect(second).toHaveBeenLastCalledWith();
+  });
+
+  it('should invoke condition without any args', () => {
+    ifElse(truthyCondition, first, second);
+    expect(truthyCondition).toHaveBeenCalledWith();
+  });
 });