bun.sh/docs/test/coverage.md

Bun's test runner includes a built-in test coverage reporter.

Enabling coverage

bun:test supports seeing which lines of code are covered by tests. To use this feature, pass --coverage to the CLI. It will print out a coverage report to the console:

$ bun test --coverage
-------------|---------|---------|-------------------
File         | % Funcs | % Lines | Uncovered Line #s
-------------|---------|---------|-------------------
All files    |   38.89 |   42.11 |
 index-0.ts  |   33.33 |   36.84 | 10-15,19-24
 index-1.ts  |   33.33 |   36.84 | 10-15,19-24
 index-10.ts |   33.33 |   36.84 | 10-15,19-24
 index-2.ts  |   33.33 |   36.84 | 10-15,19-24
 index-3.ts  |   33.33 |   36.84 | 10-15,19-24
 index-4.ts  |   33.33 |   36.84 | 10-15,19-24
 index-5.ts  |   33.33 |   36.84 | 10-15,19-24
 index-6.ts  |   33.33 |   36.84 | 10-15,19-24
 index-7.ts  |   33.33 |   36.84 | 10-15,19-24
 index-8.ts  |   33.33 |   36.84 | 10-15,19-24
 index-9.ts  |   33.33 |   36.84 | 10-15,19-24
 index.ts    |  100.00 |  100.00 |
-------------|---------|---------|-------------------

To always enable coverage reporting by default, add the following line to your bunfig.toml:

[test]

# always enable coverage
coverage = true

By default coverage reports will include test files and exclude sourcemaps. This is usually what you want, but it can be configured otherwise in bunfig.toml.

coverageSkipTestFiles = true       # default false
coverageIgnoreSourcemaps = false   # default true

Coverage thresholds

{% callout %} Note — Support for coverage reporting was added in Bun v0.7.3. {% /callout %}

It is possible to specify a coverage threshold in bunfig.toml. If your test suite does not meet or exceed this threshold, bun test will exit with a non-zero exit code to indicate the failure.

[test]

# to require 90% line-level and function-level coverage
coverageThreshold = 0.9

# to set different thresholds for lines and functions
coverageThreshold = { line = 0.9, function = 0.9 }