Unit test guidelines

Guidelines for running and writing unit tests.

Running unit tests

1. Install package dependencies:

   npm install

2. Build carta-protobuf and WebAssembly libraries:

   npm run build-protobuf
   
   npm run build-libs
   npm run build-wrappers

3. Run unit tests:

   npm test

   By default, Jest runs tests related to changed files.

   To display individual test results, use the --verbose flag:

   npm test --verbose

   For more options available in Jest, please refer to the Jest documentation.

Writing unit tests

Structures

• Directory structure: colocate the test file in the same directory and name with .test.ts/tsx suffix. For example,

  .
  └── src
      └── components
          └── AComponent
              ├── AComponent.tsx
              ├── AComponent.scss
              └── AComponent.test.tsx
      └── utilities
          └── math
              ├── math.ts
              └── math.test.ts

• Test code structure: use describe to structure the tests. For example,

  describe("[unit]", () => {
      test("[expected behavior]", () => {});
  
      describe("[sub unit]", () => {
          test("[expected behavior]", () => {});
      });
  });

• Make sure to implement low-level tests that focus on a certain class or function. Mock imported classes and functions with Jest when necessary.

• TypeScript enum: import TypeScript enum without index files to avoid compile failure.

Testing React components

• Avoid mocking blueprint.js objects to prevent having complex setups.
• Avoid testing snapshots to prevent having large files in the codebase.
• Follow the order of priority suggested by React Testing Library when querying elements.