backgroundScope

A scope for background work.

This scope is automatically cancelled when the test finishes. The coroutines in this scope are run as usual when using advanceTimeBy and runCurrent. advanceUntilIdle, on the other hand, will stop advancing the virtual time once only the coroutines in this scope are left unprocessed.

Failures in coroutines in this scope do not terminate the test. Instead, they are reported at the end of the test. Likewise, failure in the TestScope itself will not affect its backgroundScope, because there's no parent-child relationship between them.

A typical use case for this scope is to launch tasks that would outlive the tested code in the production environment.

In this example, the coroutine that continuously sends new elements to the channel will get cancelled:

@Test
fun testExampleBackgroundJob() = runTest {
  val channel = Channel<Int>()
  backgroundScope.launch {
    var i = 0
    while (true) {
      channel.send(i++)
    }
  }
  repeat(100) {
    assertEquals(it, channel.receive())
  }
}