Packages

•  package root

  Definition Classes

  root

•  package zio

  Definition Classes

  root

•  package test

  _ZIO Test_ is a featherweight testing library for effectful programs.

  _ZIO Test_ is a featherweight testing library for effectful programs.

  The library imagines every spec as an ordinary immutable value, providing tremendous potential for composition. Thanks to tight integration with ZIO, specs can use resources (including those requiring disposal), have well- defined linear and parallel semantics, and can benefit from a host of ZIO combinators.

  import zio.test._
  import zio.test.environment.Live
  import zio.clock.nanoTime
  import Assertion.isGreaterThan
  
  object MyTest extends DefaultRunnableSpec {
    def spec = suite("clock")(
      testM("time is non-zero") {
        assertM(Live.live(nanoTime))(isGreaterThan(0))
      }
    )
  }

  Definition Classes

  zio

•  package environment

  The environment package contains testable versions of all the standard ZIO environment types through the TestClock, TestConsole, TestSystem, and TestRandom modules.

  The environment package contains testable versions of all the standard ZIO environment types through the TestClock, TestConsole, TestSystem, and TestRandom modules. See the documentation on the individual modules for more detail about using each of them.

  If you are using ZIO Test and extending RunnableSpec a TestEnvironment containing all of them will be automatically provided to each of your tests. Otherwise, the easiest way to use the test implementations in ZIO Test is by providing the TestEnvironment to your program.

  import zio.test.environment._
  
  myProgram.provideLayer(testEnvironment)

  Then all environmental effects, such as printing to the console or generating random numbers, will be implemented by the TestEnvironment and will be fully testable. When you do need to access the "live" environment, for example to print debugging information to the console, just use the live combinator along with the effect as your normally would.

  If you are only interested in one of the test implementations for your application, you can also access them a la carte through the make method on each module. Each test module requires some data on initialization. Default data is included for each as DefaultData.

  import zio.test.environment._
  
  myProgram.provideM(TestConsole.make(TestConsole.DefaultData))

  Finally, you can create a Test object that implements the test interface directly using the makeTest method. This can be useful when you want to access some testing functionality without using the environment type.

  import zio.test.environment._
  
  for {
    testRandom <- TestRandom.makeTest(TestRandom.DefaultData)
    n          <- testRandom.nextInt
  } yield n

  This can also be useful when you are creating a more complex environment to provide the implementation for test services that you mix in.

  Definition Classes

  test

•  object TestRandom extends Serializable

  TestRandom allows for deterministically testing effects involving randomness.

  TestRandom allows for deterministically testing effects involving randomness.

  TestRandom operates in two modes. In the first mode, TestRandom is a purely functional pseudo-random number generator. It will generate pseudo-random values just like scala.util.Random except that no internal state is mutated. Instead, methods like nextInt describe state transitions from one random state to another that are automatically composed together through methods like flatMap. The random seed can be set using setSeed and TestRandom is guaranteed to return the same sequence of values for any given seed. This is useful for deterministically generating a sequence of pseudo-random values and powers the property based testing functionality in ZIO Test.

  In the second mode, TestRandom maintains an internal buffer of values that can be "fed" with methods such as feedInts and then when random values of that type are generated they will first be taken from the buffer. This is useful for verifying that functions produce the expected output for a given sequence of "random" inputs.

  import zio.random._
  import zio.test.environment.TestRandom
  
  for {
    _ <- TestRandom.feedInts(4, 5, 2)
    x <- random.nextIntBounded(6)
    y <- random.nextIntBounded(6)
    z <- random.nextIntBounded(6)
  } yield x + y + z == 11

  TestRandom will automatically take values from the buffer if a value of the appropriate type is available and otherwise generate a pseudo-random value, so there is nothing you need to do to switch between the two modes. Just generate random values as you normally would to get pseudo-random values, or feed in values of your own to get those values back. You can also use methods like clearInts to clear the buffer of values of a given type so you can fill the buffer with new values or go back to pseudo-random number generation.

  Definition Classes

  environment

• Buffer
• Data
• Service
• Test

zio.test.environment.TestRandom

Service