Testing

Write tests to prevent regressions and write better code.

Examples in this guide use global methods from Mocha, not Jest.

Internal

We take tests seriously. We have written and maintain a wide range of tests so we can iterate with confidence on the components, for instance, the visual regression tests provided by Argos-CI have proven to be really helpful. To learn more about our internal tests, you can have a look at the README.

While we have reached the 100% test coverage achievement, we don't encourage our users to do the same.

Userspace

What about writing tests in userspace? The Material-UI styling infrastructure uses some helper functions built on top of enzyme to make the process easier, which we are exposing. You can take advantage of them if you so choose.

Shallow rendering

Shallow rendering is useful to constrain your testing to a component as a unit. This also ensures that your tests aren't indirectly asserting behavior of child components. Shallow rendering was created to test components in isolation. This means without leaking child implementation details such as the context.

The createShallow() function can be used for this situation. Aside from wrapping the enzyme API, it provides a dive and untilSelector option.

Full DOM rendering

Full DOM rendering is ideal for use cases where you have components that may interact with DOM APIs or may require the full lifecycle in order to fully test the component (e.g., componentDidMount etc.).

The createMount() function is provided for this situation. Aside from wrapping the enzyme API, it provides a cleanUp function.

Render to string

Rendering to a string is useful to test the behavior of the components that are used on the server. You can take advantage of this to assert the generated HTML string.

The createRender() function is ideal for this. This is just an alias for the enzyme API, which is only exposed for consistency.

API

createShallow([options]) => shallow

Generate an enhanced shallow function with the needed context. Please refer to the enzyme API documentation for further details on the shallow function.

Arguments

1. options (Object [optional])
   • options.shallow (Function [optional]): The shallow function to enhance, it uses enzyme by default.
   • options.untilSelector (String [optional]): Recursively shallow renders the children until it can find the provided selector. It's useful to drill down higher-order components.
   • options.dive (Boolean [optional]): Shallow function renders the one non-DOM child of the current wrapper, and returns a wrapper around the result.
   • The other keys are forwarded to the options argument of enzyme.shallow().

Returns

shallow (shallow): A shallow function.

Examples

import { createShallow } from '@material-ui/core/test-utils';

describe('<MyComponent />', () => {
  let shallow;

  before(() => {  // This is Mocha; in Jest, use beforeAll
    shallow = createShallow();
  });

  it('should work', () => {
    const wrapper = shallow(<MyComponent />);
  });
});

createMount([options]) => mount

Generate an enhanced mount function with the needed context. Please refer to the enzyme API documentation for further details on the mount function.

Arguments

1. options (Object [optional])
   • options.mount (Function [optional]): The mount function to enhance, it uses enzyme by default.
   • The other keys are forwarded to the options argument of enzyme.mount().

Returns

mount (mount): A mount function.

Examples

import { createMount } from '@material-ui/core/test-utils';

describe('<MyComponent />', () => {
  let mount;

  before(() => {
    mount = createMount();
  });

  after(() => {
    mount.cleanUp();
  });

  it('should work', () => {
    const wrapper = mount(<MyComponent />);
  });
});

createRender([options]) => render

Generate a render to string function with the needed context. Please refer to the enzyme API documentation for further details on the render function.

Arguments

1. options (Object [optional])
   • options.render (Function [optional]): The render function to enhance, it uses enzyme by default.
   • The other keys are forwarded to the options argument of enzyme.render().

Returns

render (Function): A render to string function.

Examples

import { createRender } from '@material-ui/core/test-utils';

describe('<MyComponent />', () => {
  let render;

  before(() => {
    render = createRender();
  });

  it('should work', () => {
    const wrapper = render(<MyComponent />);
  });
});