Finding tests

bun test decides which files to run as tests by matching their paths against a set of patterns.

Default Discovery Logic

By default, bun test recursively searches the project directory for files that match these patterns:

• *.test.{js|jsx|ts|tsx|mjs|cjs|mts|cts} - Files ending with .test.js, .test.jsx, .test.ts, .test.tsx, .test.mjs, .test.cjs, .test.mts, or .test.cts
• *_test.{js|jsx|ts|tsx|mjs|cjs|mts|cts} - Files ending with _test.js, _test.jsx, _test.ts, _test.tsx, _test.mjs, _test.cjs, _test.mts, or _test.cts
• *.spec.{js|jsx|ts|tsx|mjs|cjs|mts|cts} - Files ending with .spec.js, .spec.jsx, .spec.ts, .spec.tsx, .spec.mjs, .spec.cjs, .spec.mts, or .spec.cts
• *_spec.{js|jsx|ts|tsx|mjs|cjs|mts|cts} - Files ending with _spec.js, _spec.jsx, _spec.ts, _spec.tsx, _spec.mjs, _spec.cjs, _spec.mts, or _spec.cts

Exclusions

By default, bun test ignores:

• node_modules directories
• Hidden directories (those starting with a period .)
• Files that don't have JavaScript-like extensions (based on available loaders)

Customizing Test Discovery

Position Arguments as Filters

To filter which test files run, pass additional positional arguments to bun test:

$ bun test <filter> <filter> ...

Any test file with a path that contains one of the filters runs. Filters are substring matches, not glob patterns.

For example, to run all tests in a utils directory:

$ bun test utils

This matches files like src/utils/string.test.ts and lib/utils/array_test.js.

Specifying Exact File Paths

To run a specific file in the test runner, make sure the path starts with ./ or / to distinguish it from a filter name:

$ bun test ./test/specific-file.test.ts

Filter by Test Name

To filter tests by name rather than file path, use the -t/--test-name-pattern flag with a regex pattern:

# run all tests with "addition" in the name
$ bun test --test-name-pattern addition

The pattern is matched against the test name prefixed with the labels of all its parent describe blocks, separated by spaces. For example, a test defined as:

describe("Math", () => {
  describe("operations", () => {
    test("should add correctly", () => {
      // ...
    });
  });
});

This test is matched against the string "Math operations should add correctly".

Changing the Root Directory

By default, Bun looks for test files starting from the current working directory. Change this with the root option in bunfig.toml:

[test]
root = "src"  # Only scan for tests in the src directory

Execution Order

Tests run in the following order:

1. Test files run sequentially (not in parallel)
2. Within each file, tests run sequentially in definition order