javascript - Spy on setTimeout and clearTimeout in Karma and Jasmine

Javascript - Spy on setTimeout and clearTimeout in Karma and Jasmine

To spy on setTimeout and clearTimeout in Karma and Jasmine tests, you can use Jasmine's spy functionalities to mock these functions and verify their usage. Here's how you can achieve this:

Spying on setTimeout

To spy on setTimeout, you need to mock it globally and then use Jasmine's spies to track its calls and behavior.

  1. Mocking setTimeout Globally: You can create a mock implementation of setTimeout that allows you to spy on its usage and behavior:

    // Mock setTimeout globally let setTimeoutSpy; beforeAll(() => { setTimeoutSpy = spyOn(window, 'setTimeout').and.callFake((callback, delay) => { // Call the callback immediately (or at a specified delay if needed) callback(); return 123; // Mock timer ID }); }); // Example test case it('should call setTimeout', () => { // Invoke a function that uses setTimeout myFunctionUsingSetTimeout(); // Expectations expect(setTimeoutSpy).toHaveBeenCalled(); expect(setTimeoutSpy.calls.first().args[1]).toBe(1000); // Example: Check delay (ms) });
    • Explanation:
      • spyOn(window, 'setTimeout'): Creates a spy on setTimeout globally.
      • and.callFake((callback, delay) => { ... }): Defines a fake implementation for setTimeout that immediately invokes the callback (or simulates a delay if needed).

  2. Verifying setTimeout Usage: Use Jasmine's spy assertions (toHaveBeenCalled, toHaveBeenCalledWith, etc.) to verify if setTimeout was called and with the expected arguments.

Spying on clearTimeout

Similarly, you can spy on clearTimeout to ensure that it's called correctly:

// Mock clearTimeout globally let clearTimeoutSpy; beforeAll(() => { clearTimeoutSpy = spyOn(window, 'clearTimeout').and.callFake((timerId) => { // Perform cleanup or logging if needed }); }); // Example test case it('should call clearTimeout', () => { // Invoke a function that uses clearTimeout myFunctionUsingClearTimeout(); // Expectations expect(clearTimeoutSpy).toHaveBeenCalled(); expect(clearTimeoutSpy.calls.first().args[0]).toBe(123); // Example: Check timer ID });
  • Explanation:
    • spyOn(window, 'clearTimeout'): Creates a spy on clearTimeout globally.
    • and.callFake((timerId) => { ... }): Defines a fake implementation for clearTimeout that allows you to observe its usage and behavior.

Notes:

  • Timing and Delays: Adjust the fake implementations (callFake function) as per your test requirements, such as simulating delays or immediate execution.

  • Global Scope: Ensure these spies are defined appropriately in a global setup (beforeAll) to apply to all relevant test cases.

By using Jasmine's spy functionalities to mock setTimeout and clearTimeout, you can effectively verify their usage and behavior within your Karma and Jasmine tests, ensuring that timing-related functionalities in your JavaScript code are tested thoroughly. Adjust the examples above based on your specific application logic and test scenarios.

Examples

  1. Karma Jasmine spyOn setTimeout

    • Description: How to spy on setTimeout function calls in Jasmine tests run with Karma.
    • Example Code:
      describe('Testing setTimeout', () => { it('should spy on setTimeout', () => { spyOn(window, 'setTimeout'); // Trigger the code that calls setTimeout // Example: setTimeout(() => { console.log('Delayed function executed'); }, 1000); expect(window.setTimeout).toHaveBeenCalled(); }); });

  2. Jasmine spyOn clearTimeout Karma

    • Description: Using Jasmine to spy on clearTimeout function calls within tests executed by Karma.
    • Example Code:
      describe('Testing clearTimeout', () => { it('should spy on clearTimeout', () => { spyOn(window, 'clearTimeout'); // Simulate a timeout ID to clear let timeoutId = setTimeout(() => { console.log('Delayed function executed'); }, 1000); clearTimeout(timeoutId); expect(window.clearTimeout).toHaveBeenCalledWith(timeoutId); }); });

  3. Karma Jasmine spyOn setTimeout and clearTimeout

    • Description: How to spy on both setTimeout and clearTimeout functions using Jasmine within Karma tests.
    • Example Code:
      describe('Testing setTimeout and clearTimeout', () => { it('should spy on setTimeout and clearTimeout', () => { spyOn(window, 'setTimeout'); spyOn(window, 'clearTimeout'); let timeoutId = setTimeout(() => { console.log('Delayed function executed'); }, 1000); clearTimeout(timeoutId); expect(window.setTimeout).toHaveBeenCalled(); expect(window.clearTimeout).toHaveBeenCalledWith(timeoutId); }); });

  4. Jasmine spy setTimeout not called

    • Description: Testing scenario in Jasmine where setTimeout should not be called using spies within Karma.
    • Example Code:
      describe('Testing setTimeout not called', () => { it('should expect setTimeout not to be called', () => { spyOn(window, 'setTimeout'); // No setTimeout should be triggered expect(window.setTimeout).not.toHaveBeenCalled(); }); });

  5. Karma spyOn setTimeout with parameters

    • Description: Spying on setTimeout with specific parameters in Karma tests using Jasmine.
    • Example Code:
      describe('Testing setTimeout with parameters', () => { it('should spy on setTimeout with specific parameters', () => { spyOn(window, 'setTimeout'); setTimeout(() => { console.log('Function executed with parameters'); }, 1000, 'param1', 'param2'); expect(window.setTimeout).toHaveBeenCalledWith(jasmine.any(Function), 1000, 'param1', 'param2'); }); });

  6. Jasmine spyOn clearTimeout called

    • Description: Ensuring clearTimeout is called within Jasmine tests run by Karma.
    • Example Code:
      describe('Testing clearTimeout called', () => { it('should expect clearTimeout to be called', () => { spyOn(window, 'clearTimeout'); let timeoutId = setTimeout(() => { console.log('Delayed function executed'); }, 1000); clearTimeout(timeoutId); expect(window.clearTimeout).toHaveBeenCalledWith(timeoutId); }); });

  7. Karma spyOn setTimeout multiple calls

    • Description: Spying on multiple calls to setTimeout in Karma tests using Jasmine.
    • Example Code:
      describe('Testing multiple setTimeout calls', () => { it('should spy on multiple setTimeout calls', () => { spyOn(window, 'setTimeout').and.callThrough(); setTimeout(() => { console.log('Function 1 executed'); }, 1000); setTimeout(() => { console.log('Function 2 executed'); }, 2000); expect(window.setTimeout).toHaveBeenCalledTimes(2); }); });

  8. Jasmine spyOn clearTimeout not called

    • Description: Verifying that clearTimeout is not called using Jasmine spies within Karma.
    • Example Code:
      describe('Testing clearTimeout not called', () => { it('should expect clearTimeout not to be called', () => { spyOn(window, 'clearTimeout'); // No clearTimeout should be triggered expect(window.clearTimeout).not.toHaveBeenCalled(); }); });

  9. Karma Jasmine spyOn setTimeout called with function

    • Description: Spying on setTimeout calls with specific function parameters in Karma using Jasmine.
    • Example Code:
      describe('Testing setTimeout called with function', () => { it('should spy on setTimeout with function parameter', () => { spyOn(window, 'setTimeout'); let delayedFunction = () => { console.log('Delayed function executed'); }; setTimeout(delayedFunction, 1000); expect(window.setTimeout).toHaveBeenCalledWith(delayedFunction, 1000); }); });

  10. Jasmine spyOn clearTimeout multiple calls

    • Description: Testing multiple calls to clearTimeout using Jasmine spies within Karma.
    • Example Code:
      describe('Testing multiple clearTimeout calls', () => { it('should spy on multiple clearTimeout calls', () => { spyOn(window, 'clearTimeout'); let timeoutId1 = setTimeout(() => { console.log('Function 1 executed'); }, 1000); let timeoutId2 = setTimeout(() => { console.log('Function 2 executed'); }, 2000); clearTimeout(timeoutId1); clearTimeout(timeoutId2); expect(window.clearTimeout).toHaveBeenCalledTimes(2); }); });

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