test-fns
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write usecase driven tests systematically for simpler, safer, and more readable code
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# test-fns
write usecase driven tests systematically for simpler, safer, and more readable code
# purpose
establishes a pattern of writing tests for simpler, safer, and more readable code.
by defining tests in terms of usecases (`given`, `when`, `then`) your tests are
- simpler to write
- easier to read
- safer to trust
# install
```sh
npm install --save test-fns
```
# use
```ts
type Plant = { id: number, hydration: 'DRY' | 'WET' };
const doesPlantNeedWater = (plant: Plant) => plant.hydration === 'DRY';
describe('doesPlantNeedWater', () => {
given('a plant', () => {
when('the plant doesnt have enough water', () => {
const plant: Plant = {
id: 7,
hydration: 'DRY',
};
then('it should return true', () => {
expect(doesPlantNeedWater(plant)).toEqual(true)
})
})
})
})
```
produces
```sh
PASS src/givenWhenThen.test.ts
doesPlantNeedWater
given: a plant
when: the plant doesnt have enough water
✓ then: it should return true (1 ms)
```
# features
### .runIf(condition) && .skipIf(condition)
skip running the suite if the condition is not met
```ts
describe('your test', () => {
given.runIf(onLocalMachine)('some test that should only run locally', () => {
then.skipIf(onProduction)('some test that should not run against production', () => {
expect(onProduction).toBeFalse()
})
})
})
```