Testing

Tests ensure that our application works as expected, even in edge cases, before deploying it to production. Moreover, unit tests help keep a high-quality code level during the whole development process, detecting whether new features introduce bugs or unexpected side-effects.

Deno makes it very easy to write tests since it provides a built-in test runner. We do not need to import nor configure any external library, and we can start testing our code immediately.

Naming conventions

A test file must match one of the following conditions to be processed:

1. Be named test.ts (e.g. ./utils/test.ts)

2. Ending with .test. (e.g. user.test.ts)

3. Ending with _test.ts (e.g. user_test.ts)

We can use the deno test instruction to run tests.
The command instructs the test-runner to search and execute tests in a given folder recursively. We can point to the root path of a feature or module, and the test runner will also search for tests in all nested child folders.

Test call examples:

$ deno test users/account_test.ts
// It runs only the tests in account_test.ts file

$ deno test
//runs all tests recursively inside the current directory

$ deno test utils/
//runs the tests recursively inside the utils directory

Tests formats

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