Commit 44783480 authored by Mike Greiling's avatar Mike Greiling

document the spyOnDependency method

parent c15584f2
......@@ -126,13 +126,51 @@ it('tests a promise rejection', (done) => {
});
```
#### Stubbing
#### Stubbing and Mocking
For unit tests, you should stub methods that are unrelated to the current unit you are testing.
If you need to use a prototype method, instantiate an instance of the class and call it there instead of mocking the instance completely.
Jasmine provides useful helpers `spyOn`, `spyOnProperty`, `jasmine.createSpy`,
and `jasmine.createSpyObject` to facilitate replacing methods with dummy
placeholders, and recalling when they are called and the arguments that are
passed to them. These tools should be used liberally, to test for expected
behavior, to mock responses, and to block unwanted side effects (such as a
method that would generate a network request or alter `window.location`). The
documentation for these methods can be found in the [jasmine introduction page](https://jasmine.github.io/2.0/introduction.html#section-Spies).
For integration tests, you should stub methods that will effect the stability of the test if they
execute their original behaviour. i.e. Network requests.
Sometimes you may need to spy on a method that is directly imported by another
module. GitLab has a custom `spyOnDependency` method which utilizes
[babel-plugin-rewire](https://github.com/speedskater/babel-plugin-rewire) to
achieve this. It can be used like so:
```javascript
// my_module.js
import { visitUrl } from '~/lib/utils/url_utility';
export default function doSomething() {
visitUrl('/foo/bar');
}
// my_module_spec.js
import doSomething from '~/my_module';
describe('my_module', () => {
it('does something', () => {
const visitUrl = spyOnDependency(doSomething, 'visitUrl');
doSomething();
expect(visitUrl).toHaveBeenCalledWith('/foo/bar');
});
});
```
Unlike `spyOn`, `spyOnDependency` expects its first parameter to be the default
export of a module who's import you want to stub, rather than an object which
contains a method you wish to stub (if the module does not have a default
export, one is be generated by the babel plugin). The second parameter is the
name of the import you wish to change. The result of the function is a Spy
object which can be treated like any other jasmine spy object.
Further documentation on the babel rewire pluign API can be found on
[its repository Readme doc](https://github.com/speedskater/babel-plugin-rewire#babel-plugin-rewire).
### Vue.js unit tests
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment