API Testing with Vitest

Stack

This stack illustrates the article API Testing with Vitest.

A basic set of packages to test API with TypeScript:

• Vitest — testing framework;
• Node.js fetch() as HTTP client;
• Zod — schema validation;
• date-fns — modern date utility library;
• Prettier — code formatter;
• ESLint – code linter.

Example API for testing: APOD NASA API.

How to Use

You have to have Node.js >= 21 in order to use fetch().

1. Clone repository;
2. Install dependencies: npm install
3. Run tests: npm run test

CLI Options

• Different tested host could be passed to tests through .env variable (it can be useful for testing different environments):

HOST=https://api.nasa.gov npm test

• Individual API key could be passed to tests through .env variable (otherwise, it will be used DEMO_KEY value):

API_KEY={api_key} npm test

• Run a single test or tests that match a specific filename (for example epic.test.ts):

npm test epic

• Run tests in UI watch mode:

npm run test:ui

Examples of Test Cases

Tests replicate API tests on Jest from this repository:

• apod.test.ts — test with JSON schema validation;
• epic.test.ts — test has a loop through array for checking elements with Chai assertion;
• insight-weather.test.ts — test will be conditionally skipped in an inappropriate environment.

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Concerns of the stack: Zod is highly inconvenient as JSON schema validator in case of dynamic keys inside an object with other typed keys.