Packages

Definition Classes: root

Definition Classes: root

_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.Clock.nanoTime

object MyTest extends ZIOSpecDefault {
  def spec = suite("clock")(
    test("time is non-zero") {
      for {
        time <- Live.live(nanoTime)
      } yield assertTrue(time >= 0L)
    }
  )
}

Definition Classes: zio

package diff

Definition Classes: test

package internal

Definition Classes: test

package laws

The laws package provides functionality for describing laws as values.

The laws package provides functionality for describing laws as values. The fundamental abstraction is a set of ZLaws[Caps, R]. These laws model the laws that instances having a capability of type Caps are expected to satisfy. A capability Caps[_] is an abstraction describing some functionality that is common across different data types and obeys certain laws. For example, we can model the capability of two values of a type being compared for equality as follows:

trait Equal[-A] {
  def equal(a1: A, a2: A): Boolean
}

Definitions of equality are expected to obey certain laws:

Reflexivity - a1 === a1
Symmetry - a1 === a2 ==> a2 === a1
Transitivity - (a1 === a2) && (a2 === a3) ==> (a1 === a3)

These laws define what the capabilities mean and ensure that it is safe to abstract across different instances with the same capability.

Using ZIO Test, we can represent these laws as values. To do so, we define each law using one of the ZLaws constructors. For example:

val transitivityLaw = ZLaws.Laws3[Equal]("transitivityLaw") {
  def apply[A: Equal](a1: A, a2: A, a3: A): TestResult =
    ???
}

We can then combine laws using the + operator:

val reflexivityLaw: = ???
val symmetryLaw:    = ???

val equalLaws = reflexivityLaw + symmetryLaw + transitivityLaw

Laws have a run method that takes a generator of values of type A and checks that those values satisfy the laws. In addition, objects can extend ZLawful to provide an even more convenient syntax for users to check that instances satisfy certain laws.

object Equal extends Lawful[Equal]

object Hash extends Lawful[Hash]

object Ord extends Lawful[Ord]

checkAllLaws(Equal + Hash + Ord)(Gen.int)

Note that capabilities compose seamlessly because of contravariance. We can combine laws describing different capabilities to construct a set of laws requiring that instances having all of the capabilities satisfy each of the laws.

Definition Classes: test

package magnolia

Definition Classes: test

package poly

Definition Classes: test

package refined

Definition Classes: test

package render

Definition Classes: test

package results

Definition Classes: test

package scalacheck

This package provides helpers to integrate *some* ScalaCheck primitives to their ZIO equivalents.

This package provides helpers to integrate *some* ScalaCheck primitives to their ZIO equivalents. Currently available helpers:

Converting ScalaCheck Generators to ZIO Generators
Asserting a ScalaCheck Prop with ZIO
Asserting a ScalaCheck Properties with ZIO

**Generators**

This functionality converts legacy ScalaCheck generators to ZIO Test generators to support upgrading to ZIO Test without having to reimplement existing generators. To use it import this module and then call toGenZIO on any existing ScalaCheck generator. For example:

import org.scalacheck.Arbitrary

import zio._
import zio.test._
import zio.test.scalacheck._

val anyInt: Gen[Any, Int] =
  Arbitrary.arbitrary[Int].toGenZIO

**Asserting ScalaCheck Prop and Properties**

This functionality generates ZIO Assertions from either ScalaCheck Prop or Properties. This helps with integrating other libraries that provide ScalaCheck properties as helpers, i.e. cats-laws.

Prop example:

import org.scalacheck.Prop
import org.scalacheck.Test.{ Parameters => ScalaCheckParameters }

import zio._
import zio.test._
import zio.test.scalacheck._

val prop: Prop = Prop.forAll { (n: Int, m: Int) =>
  n + m == m + n
}
val resultDefault: TestResult = prop.assertZIO()

val resultWithCustomizations: TestResult =
  prop.assertZIO("My Prop Name", ScalaCheckParameters.default.withMaxSize(10))

Properties example:

import org.scalacheck.{ Prop, Properties }
import org.scalacheck.Test.{ Parameters => ScalaCheckParameters }

import zio._
import zio.test._
import zio.test.scalacheck._

object MyProperties extends Properties("MyProperties") {
  property("myProp") = Prop.forAll { (n: Int, m: Int) =>
    n + m == m + n
  }
}

* val resultDefault: TestResult = MyProperties.assertZIO()

// Beware that we can't provide a custom name here, it will be
// taken from the `Properties` name parameter
val resultWithCustomizations: TestResult =
  MyProperties.assertZIO(ScalaCheckParameters.default.withMaxSize(10))