@conduitvc/jest
v4.0.0
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> Neutrino preset that supports testing projects with Jest according to Conduit's process and settings.
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@conduitvc/jest
Neutrino preset that supports testing projects with Jest according to Conduit's process and settings.
Features
- Zero upfront configuration necessary to start testing
- Babel compilation that compiles your tests using the same Babel options used by your source code
- Source watching for re-running of tests on change
- Collecting test coverage information and generating report
- Easily extensible to customize your testing as needed
Requirements
- Node.js ^8.10 or 10+
- Yarn v1.2.1+, or npm v5.4+
- Neutrino 9 and one of the Neutrino build presets
- webpack 4
- Jest 23
Installation
@conduitvc/jest
can be installed via the Yarn client. Inside your project,
make sure @conduitvc/jest
and jest
are development dependencies. You will
also be using another Conduit preset for building your application source code.
❯ yarn add --dev @conduitvc/jest jest
Installation: React Testing
Jest is often used in the testing of React components. If you are using this
preset in a React application, which most likely means you are using
@conduitvc/react
, you should also consider adding React's TestUtils and
potentially a higher-level abstraction such as Airbnb's Enzyme. These should be
development dependencies of your project.
❯ yarn add --dev react-addons-test-utils enzyme
See the React's Test Utils documentation for specifics on React testing with this approach.
Project Layout
@conduitvc/jest
follows the standard
project layout specified by Neutrino.
This means that by default all project test code should live in a directory
named test
in the root of the project. Test files end in either _test.js
,
.test.js
, _test.jsx
, or .test.jsx
.
Quickstart
After adding the Jest preset to your Neutrino-built project, add a new directory
named test
in the root of the project, with a single JS file named
simple_test.js
in it.
❯ mkdir test && touch test/simple_test.js
Edit your test/simple_test.js
file with the following:
describe('simple', () => {
it('should be sane', () => {
expect(false).not.toBe(true);
});
});
Now update your project's .neutrinorc.js
to add the @conduitvc/jest
preset.
In this example, let's pretend this is a Node.js project:
module.exports = {
use: [
'@conduitvc/node',
'@conduitvc/jest',
],
};
Create a jest.config.js
file in the root of the project that will be used by
the Jest CLI:
// jest.config.js
const neutrino = require('neutrino');
process.env.NODE_ENV = process.env.NODE_ENV || 'test';
module.exports = neutrino().jest();
Then add these scripts entries to your package.json
to simplify running Jest:
{
"scripts": {
"test": "jest",
"test:watch": "jest --watch"
}
}
Run the tests, and view the results in your console:
❯ yarn test
PASS test/simple_test.js
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 3.265s
Ran all test suites.
To run tests against files from your source code, simply import them:
import thingToTest from '../src/thing';
For more details on specific Jest usage, please refer to their documentation.
Executing single tests
By default this preset will execute every test file located in your test directory ending in the appropriate file extension. Pass specific test file names to the Jest CLI to override this.
Watching for changes
@condtuivc/jest
can watch for changes on your source directory and
subsequently re-run tests. Simply pass --watch
to the Jest CLI (for example
by using the test:watch
scripts entry above).
Coverage reporting
Jest has an integrated coverage reporter, which requires no configuration. To
collect test coverage information and generate a report, use the CLI's
--coverage
option.
Additional CLI options
See the Jest CLI options documentation.
Preset options
You can provide custom options and have them merged with this preset's default
options, which are subsequently passed to Jest. You can modify Jest settings
from .neutrinorc.js
by overriding with any options Jest accepts. In a
standalone Jest project this is typically done in the package.json file, but
@conduitvc/jest
allows configuration through this mechanism as well. This
accepts the same configuration options as outlined in the
Jest documentation. Use an array pair
instead of a string to supply these options.
Example: Turn off bailing on test failures.
module.exports = {
use: [
['@conduitvc/jest', { bail: false }],
],
};
You might need to instruct Jest to load some setup scripts (e.g. when you use Enzyme).
Example: Jest setup scripts.
module.exports = {
use: [
['@conduitvc/jest', {
// setup script for the framework
setupTestFrameworkScriptFile: '<rootDir>/test-setup.js',
// and / or shims
setupFiles: [
'<rootDir>/shim.js'
],
}],
],
};
test-setup.js for the example above
const Enzyme = require('enzyme');
const EnzymeAdapter = require('enzyme-adapter-react-16');
// Setup enzyme's react adapter
Enzyme.configure({ adapter: new EnzymeAdapter() });
shim.js for the example above
global.requestAnimationFrame = (callback) => {
setTimeout(callback, 0);
};
Customizing
To override the test configuration, start with the documentation on
customization. @conduitvc/jest
creates some conventions to make overriding the configuration easier once you
are ready to make changes.
Rules
The following is a list of rules and their identifiers which can be overridden:
| Name | Description | NODE_ENV |
| --- | --- | --- |
| compile
| Compiles JS files from the test
directory using adopted Babel settings from other build presets. Contains a single loader named babel
. | all |
Override configuration
By following the customization guide
and knowing the rule, and loader IDs above, you can override and augment testing
by providing a function to your .neutrinorc.js
use array. You can also make
this change from the Neutrino API when using the use
method.
In a standalone Jest project this is typically done in the package.json file,
but @conduitvc/jest
allows configuration through this mechanism as well. This
accepts the same configuration options as outlined in the
Jest documentation. Use an array pair
instead of a string to supply these options.
Example: Add a custom Babel plugin when testing:
module.exports = {
use: [
'@conduitvc/jest',
(neutrino) => {
if (process.env.NODE_ENV === 'test') {
neutrino.config.module
.rule('compile')
.use('babel')
.tap(options => merge(options, {
env: {
test: {
plugins: ['custom-babel-plugin']
},
},
}));
}
},
],
};