How does Bootstrap's test suite work?

Bootstrap uses QUnit and Sinon. Each plugin has a file dedicated to its tests in unit/<plugin-name>.js.

• unit/ contains the unit test files for each Bootstrap plugin.
• vendor/ contains third-party testing-related code (QUnit, jQuery and Sinon).
• visual/ contains "visual" tests which are run interactively in real browsers and require manual verification by humans.

To run the unit test suite via Karma, run npm run js-test.

To run the unit test suite via a real web browser, open index.html in the browser.

How do I add a new unit test?

1. Locate and open the file dedicated to the plugin which you need to add tests to (unit/<plugin-name>.js).
2. Review the QUnit API Documentation and use the existing tests as references for how to structure your new tests.
3. Write the necessary unit test(s) for the new or revised functionality.
4. Run npm run js-test to see the results of your newly-added test(s).

Note: Your new unit tests should fail before your changes are applied to the plugin, and should pass after your changes are applied to the plugin.

What should a unit test look like?

• Each test should have a unique name clearly stating what unit is being tested.
• Each test should test only one unit per test, although one test can include several assertions. Create multiple tests for multiple units of functionality.
• Each test should begin with [assert.expect](https://api.qunitjs.com/assert/expect/) to ensure that the expected assertions are run.
• Each test should follow the project's JavaScript Code Guidelines

Code coverage

Currently we're aiming for at least 80% test coverage for our code. To ensure your changes meet or exceed this limit, run npm run js-compile && npm run js-test and open the file in js/coverage/lcov-report/index.html to see the code coverage for each plugin. See more details when you select a plugin and ensure your change is fully covered by unit tests.

Example tests

js
// Synchronous test
QUnit.test('should describe the unit being tested', function (assert) {
  assert.expect(1)
  var templateHTML = '<div class="alert alert-danger fade show">' +
        '<a class="close" href="#" data-dismiss="alert">×</a>' +
        '<p><strong>Template necessary for the test.</p>' +
        '</div>'
  var $alert = $(templateHTML).appendTo('#qunit-fixture').bootstrapAlert()

  $alert.find('.close').trigger('click')

  // Make assertion
  assert.strictEqual($alert.hasClass('show'), false, 'remove .show class on .close click')
})

// Asynchronous test
QUnit.test('should describe the unit being tested', function (assert) {
  assert.expect(2)
  var done = assert.async()

  var $tooltip = $('<div title="tooltip title"></div>').bootstrapTooltip()
  var tooltipInstance = $tooltip.data('bs.tooltip')
  var spyShow = sinon.spy(tooltipInstance, 'show')

  $tooltip.appendTo('#qunit-fixture')
    .on('shown.bs.tooltip', function () {
      assert.ok(true, '"shown" event was fired after calling "show"')
      assert.ok(spyShow.called, 'show called')
      done()
    })
    .bootstrapTooltip('show')
})