97 lines
2.4 KiB
Markdown
97 lines
2.4 KiB
Markdown
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# mocha-foam
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An experimental Mocha BDD wrapper for fast-check.
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## Contents
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- [mocha-foam](#mocha-foam)
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- [Contents](#contents)
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- [Install](#install)
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- [Usage](#usage)
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- [Build](#build)
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- [License](#license)
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## Install
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Add `mocha-foam` to your project as a dev dependency:
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```shell
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> yarn add -D mocha-foam
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```
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## Usage
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This is a BDD-style wrapper around `fc.check(fc.asyncProperty(...))`, and supports all of the same [Arbitraries](https://github.com/dubzzz/fast-check/blob/main/documentation/Arbitraries.md)
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that fast-check normally provides.
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The entrypoint function is `over` and the library is provided as an ES module:
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```typescript
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import { expect } from 'chai';
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import { integer } from 'fast-check';
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import { over } from 'mocha-foam';
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describe('example properties', () => {
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over('some numbers', integer(), (it) => {
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it('should be even', (n: number) => {
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return n % 2 === 0;
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});
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it('should be odd', async (n: number) => {
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expect(n % 2).to.equal(1);
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});
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});
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});
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```
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Most Mocha features, like `beforeEach` and `afterEach` hooks, work correctly within the suite defined by `over`.
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You can pass additional run parameters to the fast-check Runner after the suite callback:
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```typescript
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describe('more examples', () => {
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over('some UUIDs', uuid(), (it) => {
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// beforeEach hooks work normally, since the wrapped it calls through to real it
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beforeEach(() => {
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console.log('before each UUID test');
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});
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it('should be a good one', (id: string) => {
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return id[9] !== 'a';
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});
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it('should be long enough', (id: string) => {
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expect(id).to.have.length.greaterThan(2);
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});
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}, {
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// fast-check parameters are supported, like examples
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examples: ['a', 'b'],
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numRuns: 1_000,
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});
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over('mapped properties', tuple(lorem(), integer()).map(([a, b]) => a.substr(b)), (it) => {
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it('should have content', (text: string) => {
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return text.length > 0;
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});
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}, {
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// error formatting can be overridden with a custom handler, or fast-check's default reporter
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errorReporter: defaultReportMessage,
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});
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});
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```
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## Build
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To build `mocha-foam`, run `make`. The build depends on:
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- Node 14+
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- Yarn 1.x
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To run small tests with coverage, run `make cover`.
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The `make help` target will print help for the available targets.
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## License
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`mocha-foam` is released under [the MIT license](LICENSE.md).
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