ZIO Test

Early beta version of dependency-free test library for (pure FP) effectful programs. Critical constructs include:

• Spec - A value-level representation for a specification
• ZSpec - An alias for a Spec whose tests are ZIO effects
• Predicate - Composable predicates with detailed error messages
• zio.test.{ assert, assertM, check, checkAll, checkSome, suite, test, testM } - The building blocks for constructing specs
• RunnableSpec - Specs will extend this (or DefaultRunnableSpec)
• TestRunner - Every runnable spec points to a spec runner
• TestAspect - Features that can be added to specs, such as timeouts, retries, etc.
• Gen - Generators for property-testing based on ZIO Stream

ZIO Test has excellent support for environmental effects; specs that use the ZIO environmental effects (Console, Clock, etc.) will automatically (in DefaultRunnableSpec) be provided with a newly-created mock environment, meaning they will execute fast and deterministically. Users can supply their own mock environments when extending RunnableSpec.

ZIO Test Example:

class MySpec extends DefaultRunnableSpec {
  import Predicate._
  import zio.random._
  import zio.test.TestAspect.{ flaky, timeout }

  suite("An example suite") {
    test("addition") {
      assert(2 + 2, equals(4))
    },
    testM("random.nextDouble") { 
      assertM(nextDouble, isGreaterThanEqual(0.0) && isLessThanEqual(1.0)) 
    },
    (flaky >>> timeout(10.seconds)) {
      testM("flaky random.nextDouble") {
        assertM(nextDouble, isGreaterThan(0.5))
      }
    }
  }
}

Other notable changes

ZIO

• Enhance support for Option and Either (#1175) by @dorsev
• Add Random.shuffle method (#1185) by @ioleo
• Add real companion objects to Task, TaskR, UIO and IO (#805) by @TheMayoras
• Rename TaskR to RIO and add an alias UIOR[R, A] = ZIO[R, Nothing, A] (#1154) by @ioleo
• Fix #1165 - ZIO.foreachParN should not use more than n fibers (#1187) by @adamgfraser
• Implement ZIO#foldCause (#1243) by @vasilmkd
• Add whenCase and whenCaseM to ZIO and ZManaged (#1246) by @ghostdogpr
• Add "Setter" / "Update" Methods to Mock Services (#1252) by @adamgfraser
• Add ZIO.replicate method (#1262) by @dorsev
• Add ZIO#eventually (#1302) by @vasilmkd
• Add ZIO#left, ZIO#right and ZIO#head (#1223) by @adamgfraser
• Add ZIO#flattenErrorOption, ZIO#none, ZIO#optional, ZIO#some (#1221) by @jczuchnowski
• Add ZIO.effectSuspend, ZIO.effectSuspendTotal, ZIO.effectSuspendTotalWith and ZIO.effectSuspendWith (#926) by @kamilkloch

ZManaged

• Introduce real companion object for Managed (#1111) (#1169) by @andreamarcolin
• Add ZStream#ensuringFirst (#1209) by @adamgfraser
• Make ZManaged#mergeAllParN and ZManaged#reduceAllParN tolerant to finalizer defects (#1256) by @adamgfraser
• Add ZManaged.makeExit that allows to handle Exit by the finalizer. (#1232) by @vvlevykin

ZSchedule

• add doWhileM, doUntilM for ZSchedule (#1199) by @contrun
• add collectWhile and collectUntil (#1287) by @contrun

ZStream and ZSink

• Enhanced ZStream spaced to also emit schedule's output (#1120) (#1162) by @dag2ww
• Add ZStream#throttleEnforce and ZStream#throttleEnforceM (#1027) (#1155) by @vasilmkd
• Add ZStream#throttleShape, ZStream#throttleShapeM (#1195) by @vasilmkd
• Add ZStream#effectAsync and variants (#1118) by @dariusrobson
• Add ZStream#aggregate, ZStream#aggregateWithin (#1137) by @iravid
• Add burst control to the existing Stream throttling combinators (#1205) by @vasilmkd
• Add ZStream#flatMapParSwitch (#1222) by @vasilmkd
• Add sinks for decoding UTF-8 bytes and byte chunks (#1342) by @iravid

Promise

• Changed Promise#done to take an Exit (#1251) by @mtsokol

Semaphore

• Implement Semaphore#withPermitsManaged (#1293) by @vasilmkd