Testing Typescript Projects

This page will discuss common topics around working with test suites using the Mill build tool

Defining Unit Test Suites

package build

import mill._, javascriptlib._

object bar extends TypeScriptModule {
  object test extends TypeScriptTests with TestModule.Jest
}

object baz extends TypeScriptModule {
  object test extends TypeScriptTests with TestModule.Vitest
}

object foo extends TypeScriptModule {
  object test extends TypeScriptTests with TestModule.Mocha
}

object qux extends TypeScriptModule {
  object test extends TypeScriptTests with TestModule.Jasmine
}

Documentation for mill.example.javascriptlib This build defines 4 modules bar, baz, foo & qux with test suites configured to use Jest, Vitest, Mocaha & Jasmine respectively

> mill foo.test
...
...4 passing...
...

> mill bar.test
...Calculator
...
Test Suites:...1 passed, 1 total...
Tests:...4 passed, 4 total...
...

> mill baz.test
.../calculator.test.ts...
...Test Files  1 passed...
...Tests  4 passed...
...

> mill qux.test
...
4 specs, 0 failures

Test Dependencies

build.mill (download, browse)

package build

import mill._, javascriptlib._

object bar extends TypeScriptModule {
  def npmDeps = Seq("immutable@4.3.7")
  object test extends TypeScriptTests with TestModule.Jest
}

object foo extends TypeScriptModule {
  def moduleDeps = Seq(bar)
  object test extends TypeScriptTests with TestModule.Jest
}

Documentation for mill.example.javascriptlib In this example, foo depend on bar, but we also make foo.test depend on bar.test.

That lets foo.test make use of the default function exported from bar/test/utils/bar.tests.utils.ts, allowing us to re-use this test helper throughout multiple modules' test suites.

> mill foo.test
PASS .../foo.test.ts
...
Test Suites:...1 passed, 1 total...
Tests:...3 passed, 3 total...
...

> mill bar.test
PASS .../bar.test.ts
...
Test Suites:...1 passed, 1 total...
Tests:...2 passed, 2 total...
...