https://github.com/ddamato/assert-css

Assert that CSS is constructed properly
https://github.com/ddamato/assert-css

Last synced: 4 days ago
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Assert that CSS is constructed properly

• Host: GitHub
• URL: https://github.com/ddamato/assert-css
• Owner: ddamato
• License: isc
• Created: 2024-05-08T16:43:56.000Z (6 months ago)
• Default Branch: main
• Last Pushed: 2024-05-09T22:56:16.000Z (6 months ago)
• Last Synced: 2024-09-15T08:24:36.101Z (2 months ago)
• Language: JavaScript
• Homepage:
• Size: 69.3 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# assert-css

[![npm version](https://img.shields.io/npm/v/assert-css.svg)](https://www.npmjs.com/package/assert-css)

Assert that CSS is constructed properly.

## Usage

```js

import assertCss from 'assert-css';

describe('CSS generation', function () {

  it('should have the expected CSS', function () {

    assertCss('body { margin: 0; }').selector('body').includes('margin', 0);

  });

});

```

### Chains

The project uses object chaining to complete assertions.

#### `.selector()`

The `.selector()` method has the following possible chains:

- `.selector().exists()`, asserts that the selector is within the CSS.

- `.selector().not.exists()`, asserts that the selector is not within the CSS.

- `.selector().includes(property)`, asserts that the given property exists within the selector.

- `.selector().not.includes(property)`, asserts that the given property does not exist within the selector.

- `.selector().includes(property, value)`, asserts that the property-value pair exists within the selector.

- `.selector().not.includes(property, value)`, asserts that the property-value pair does not exist within the selector.

The `value` within an `includes()` chain can be a custom validator function. This will pass in the resolved value as a string. Return `true` when a match is expected, false to throw an exception.

```js

assertCss('body { margin: 0 1rem }')

  .selector('body')

  .includes('margin', (value) => value.includes('1rem')); // true

```

The given selector must be accurate to the expectation within the CSS. In other words:

```js

assertCss('body[data-theme] { margin: 0 }').selector('body').exists(); // false

assertCss('body[data-theme] { margin: 0 }').selector('body').not.exists(); // true

assertCss('body[data-theme] { margin: 0 }').selector('body[data-theme]').exists(); // true

```

Also, note that this will not dive into at-rules. To check for existence within an at-rule, use `.atRule()` with the appropriate chain.

#### `.atRule()`

Similar `.selector()` in that this checks against the current CSS at-rule and its possible values with some differences:

- `.includes(value)`, completes a generic `String.includes()` against the current value. This is because various at-rule specifications do not have a repeatable construction. So `(max-width: 800px)` will match against `max-width`, `800` and `800px` as examples. You may provide a function here instead for custom matching.

- `.selector()`, is chainable off of `.atRule()` to check for specific selectors within an at-rule with all expected chains further.

See [tests](./test/assert-css.test.js) for possible example chains.