Added TestControl, with first-class support for time mocking

build.sbt

@@ -206,6 +206,8 @@ val ScalaCheckVersion = "1.15.4"
 val DisciplineVersion = "1.2.2"
 val CoopVersion = "1.1.1"
 
+val MacrotaskExecutorVersion = "0.2.0"
+
 replaceCommandAlias("ci", CI.AllCIs.map(_.toString).mkString)
 
 addCommandAlias(CI.JVM.command, CI.JVM.toString)
@@ -264,9 +266,23 @@ lazy val kernel = crossProject(JSPlatform, JVMPlatform)
   .in(file("kernel"))
   .settings(
     name := "cats-effect-kernel",
-    libraryDependencies ++= Seq(
-      ("org.specs2" %%% "specs2-core" % Specs2Version % Test).cross(CrossVersion.for3Use2_13),
-      "org.typelevel" %%% "cats-core" % CatsVersion)
+    libraryDependencies += "org.typelevel" %%% "cats-core" % CatsVersion)
+  .jvmSettings(libraryDependencies += {
+    if (isDotty.value)
+      ("org.specs2" %%% "specs2-core" % Specs2Version % Test).cross(CrossVersion.for3Use2_13)
+    else
+      "org.specs2" %%% "specs2-core" % Specs2Version % Test
+  })
+  .jsSettings(
+    libraryDependencies += {
+      if (isDotty.value)
+        ("org.specs2" %%% "specs2-core" % Specs2Version % Test)
+          .cross(CrossVersion.for3Use2_13)
+          .exclude("org.scala-js", "scala-js-macrotask-executor_sjs1_2.13")
+      else
+        "org.specs2" %%% "specs2-core" % Specs2Version % Test
+    },
+    libraryDependencies += "org.scala-js" %%% "scala-js-macrotask-executor" % MacrotaskExecutorVersion % Test
   )
 
 /**
@@ -281,7 +297,10 @@ lazy val kernelTestkit = crossProject(JSPlatform, JVMPlatform)
     libraryDependencies ++= Seq(
       "org.typelevel" %%% "cats-free" % CatsVersion,
       "org.scalacheck" %%% "scalacheck" % ScalaCheckVersion,
-      "org.typelevel" %%% "coop" % CoopVersion)
+      "org.typelevel" %%% "coop" % CoopVersion),
+    mimaBinaryIssueFilters ++= Seq(
+      ProblemFilters.exclude[DirectMissingMethodProblem](
+        "cats.effect.kernel.testkit.TestContext.this"))
   )
 
 /**
@@ -380,8 +399,7 @@ lazy val core = crossProject(JSPlatform, JVMPlatform)
     javacOptions ++= Seq("-source", "1.8", "-target", "1.8")
   )
   .jsSettings(
-    libraryDependencies += "org.scala-js" %%% "scala-js-macrotask-executor" % "0.2.0"
-  )
+    libraryDependencies += "org.scala-js" %%% "scala-js-macrotask-executor" % MacrotaskExecutorVersion)
 
 /**
  * Test support for the core project, providing various helpful instances like ScalaCheck
@@ -392,7 +410,21 @@ lazy val testkit = crossProject(JSPlatform, JVMPlatform)
   .dependsOn(core, kernelTestkit)
   .settings(
     name := "cats-effect-testkit",
-    libraryDependencies ++= Seq("org.scalacheck" %%% "scalacheck" % ScalaCheckVersion))
+    libraryDependencies += "org.scalacheck" %%% "scalacheck" % ScalaCheckVersion)
+  .jvmSettings(libraryDependencies += {
+    if (isDotty.value)
+      ("org.specs2" %%% "specs2-core" % Specs2Version % Test).cross(CrossVersion.for3Use2_13)
+    else
+      "org.specs2" %%% "specs2-core" % Specs2Version % Test
+  })
+  .jsSettings(libraryDependencies += {
+    if (isDotty.value)
+      ("org.specs2" %%% "specs2-core" % Specs2Version % Test)
+        .cross(CrossVersion.for3Use2_13)
+        .exclude("org.scala-js", "scala-js-macrotask-executor_sjs1_2.13")
+    else
+      "org.specs2" %%% "specs2-core" % Specs2Version % Test
+  })
 
 /**
  * Unit tests for the core project, utilizing the support provided by testkit.
@@ -422,16 +454,28 @@ lazy val std = crossProject(JSPlatform, JVMPlatform)
   .dependsOn(kernel)
   .settings(
     name := "cats-effect-std",
+    libraryDependencies += "org.scalacheck" %%% "scalacheck" % ScalaCheckVersion % Test)
+  .jvmSettings(libraryDependencies += {
+    if (isDotty.value)
+      ("org.specs2" %%% "specs2-scalacheck" % Specs2Version % Test)
+        .cross(CrossVersion.for3Use2_13)
+        .exclude("org.scalacheck", "scalacheck_2.13")
+        .exclude("org.scalacheck", "scalacheck_sjs1_2.13")
+    else
+      "org.specs2" %%% "specs2-scalacheck" % Specs2Version % Test
+  })
+  .jsSettings(
     libraryDependencies += {
       if (isDotty.value)
         ("org.specs2" %%% "specs2-scalacheck" % Specs2Version % Test)
           .cross(CrossVersion.for3Use2_13)
+          .exclude("org.scala-js", "scala-js-macrotask-executor_sjs1_2.13")
           .exclude("org.scalacheck", "scalacheck_2.13")
           .exclude("org.scalacheck", "scalacheck_sjs1_2.13")
       else
         "org.specs2" %%% "specs2-scalacheck" % Specs2Version % Test
     },
-    libraryDependencies += "org.scalacheck" %%% "scalacheck" % ScalaCheckVersion % Test
+    libraryDependencies += "org.scala-js" %%% "scala-js-macrotask-executor" % MacrotaskExecutorVersion % Test
   )
 
 /**

core/shared/src/main/scala/cats/effect/IO.scala

@@ -545,6 +545,19 @@ sealed abstract class IO[+A] private () extends IOPlatform[A] {
   def redeemWith[B](recover: Throwable => IO[B], bind: A => IO[B]): IO[B] =
     attempt.flatMap(_.fold(recover, bind))
 
+  def replicateA(n: Int): IO[List[A]] =
+    if (n <= 0)
+      IO.pure(Nil)
+    else
+      flatMap(a => replicateA(n - 1).map(a :: _))
+
+  // TODO PR to cats
+  def replicateA_(n: Int): IO[Unit] =
+    if (n <= 0)
+      IO.unit
+    else
+      flatMap(_ => replicateA_(n - 1))
+
   /**
    * Returns an IO that will delay the execution of the source by the given duration.
    */
@@ -1450,6 +1463,9 @@ object IO extends IOCompanionPlatform with IOLowPriorityImplicits {
     override def productR[A, B](left: IO[A])(right: IO[B]): IO[B] =
       left.productR(right)
 
+    override def replicateA[A](n: Int, fa: IO[A]): IO[List[A]] =
+      fa.replicateA(n)
+
     def start[A](fa: IO[A]): IO[FiberIO[A]] =
       fa.start
 

example/js/src/main/scala/cats/effect/example/Example.scala

@@ -17,8 +17,6 @@
 package cats.effect
 package example
 
-import cats.syntax.all._
-
 object Example extends IOApp {
 
   def run(args: List[String]): IO[ExitCode] =