108 lines
3.1 KiB
Markdown
108 lines
3.1 KiB
Markdown
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# Writing tests with `womm`
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## Concepts
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WOMM tests use the same high-level concepts present in other test runners like [Jest](https://github.com/facebook/jest) or [Node's built-in test
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library](https://nodejs.org/api/test.html).
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Test suites are composed of `describe` blocks that allow organizing individual test cases, defined by `it` or `test`
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blocks, into meaningful groups. Each test case can have one or more assertion -- you can come up with your own assertion
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mechanism, use Node's `assert` library or leverage the `except` built-ins that provide a good range of utilities to
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compare and test values.
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### Basic example
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Here's an example of a basic group of tests you might find in your own application:
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```ts
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import { describe, test, expect } from 'works-on-my-machine'
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describe('Testing some math', () => {
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test('Addition adds', () => {
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expect(1+1).toEqual(2)
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})
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test('Subtraction subtracts', () => {
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expect(2-1).toEqual(1)
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})
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})
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```
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In this example, each of the two test cases is nested under the "Testing some math" group for convenience.
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### Parametrization
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If you find that your tests present a lot of redundant logic (often accounting for the same test logic being run with
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different input), you might want to try parametrizing them using `each`:
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```ts
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import { describe, test, expect } from 'works-on-my-machine'
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test.each([[1,1], [2,2]])(([first, second]) => {
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expect(first).toEqual(second)
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})
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```
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In this case, the test logic is executed with each of the arrays of values provided to `each`.
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### Lifecycle hooks
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Often, tests have setup and teardown steps. You can enshrine those in your `describe` blocks using `beforeEach` and
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`afterEach` blocks:
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```ts
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import { describe, test, expect, afterEach, beforeEach } from 'works-on-my-machine'
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describe('Testing some math', () => {
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beforeEach(() => {
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// Some setup code...
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})
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afterEach(() => {
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// Some teardown code...
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})
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test('Addition adds', () => {
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expect(1+1).toEqual(2)
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})
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})
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```
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When `afterEach` or `beforeEach` are used, the functions passed to them are executed before and after each test case
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contains in the `describe` they are in. In the example above, any test within "Testing some math" will have the
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`beforeEach` be executed before, and the `afterEach`, after.
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:warning: Note that the `beforeEach` and `afterEach` hooks can only be defined once per `describe` block.
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If `describe` blocks are nested, the lifecycle hooks defined in each are executed from the outside in:
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```ts
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import { describe, test, expect, afterEach, beforeEach } from 'works-on-my-machine'
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describe('Testing some math', () => {
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beforeEach(() => {
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// Executed first, before each test.
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})
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afterEach(() => {
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// Executed first, after each test.
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})
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describe('Testing more precise math', () => {
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beforeEach(() => {
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// Executed second, before each test.
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})
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afterEach(() => {
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// Executed second, after each test.
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})
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test('Addition adds', () => {
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expect(1+1).toEqual(2)
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})
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})
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})
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```
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