Using the test command

Included as part of the main binary, Deno also provides a test runner. The command for it, not surprisingly, is called test. In this section, we'll explore it and run a couple of tests.

In this section, we'll mainly explore the command itself and not the test syntax. We'll look at the syntax and best practices for it in more depth in a dedicated chapter later on the book.

The test command finds files to run based on the {*_,*.,}test.{js,mjs,ts,jsx,tsx} glob expression.

Since glob expressions might not be too intuitive to read, we'll explain them briefly.

It matches any files with the js, mjs, ts, jsx, and tsx extensions and that have test in their name preceded by an underscore (_) or a dot (.)

A few examples of files that will match the expression and be considered tests are as follows:

• example.test.ts
• example_test.js
• example.test.jsx
• example_test.mjs

Deno tests also run inside the sandbox environment...