Tests

Running Tests

First you must configure your development environment per ../CONTRIBUTING.md

There are two test suites associated with Mapbox GL JS

• yarn test runs quick unit tests
• yarn run test-suite runs slower integration tests

To run individual tests:

• Unit tests: yarn test-unit path/to/file.test.js where the path begins within the /test/unit/ directory
• Render tests: yarn test-render render-test-name

Writing Unit Tests

• You must not share variables between test cases. All test fixtures must be wrapped in create functions. This ensures each test is run in an isolated environment.
• You should not mock any internal domain objects. Internal domain objects include Style, Map, Transform, and Dispatcher. If this is difficult because of some interface, refactor that interface. This ensures that tests accurately exercise the code paths used in production.
• You should test one return value or side effect per test case. Feel free to pull shared logic into a function. This ensures that tests are easy to understand and modify.
• You should only test the return values and global side effects of methods. You should not not test internal behavior, such as that another method is called with particular arguments. This ensures that method implementations may change without causing test failures.
• You must not make network requests in test cases. This rule holds in cases when result isn't used or is expected to fail. You may use window.useFakeXMLHttpRequest and window.server per the Sinon API to simulate network requests. This ensures that tests are reliable, able to be run in an isolated environment, and performant.
• You should use clear input space partitioning schemes. Look for edge cases! This ensures that tests suites are comprehensive and easy to understand.

Spies, Stubs, and Mocks

The test object is augmented with methods from Sinon.js for spies, stubs, and mocks. For example, to use Sinon's spy API, call t.spy(...) within a test.

The test framework is set up such that spies, stubs, and mocks on global objects are restored at the end of each test.