Retry: add MTL-specific tests

typelevel · Jul 28, 2024 · 3cbaeff · 3cbaeff
1 parent ff5bc74
commit 3cbaeff
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Showing 4 changed files with 118 additions and 9 deletions.
diff --git a/core/shared/src/main/scala/cats/effect/IO.scala b/core/shared/src/main/scala/cats/effect/IO.scala
@@ -662,14 +662,14 @@ sealed abstract class IO[+A] private () extends IOPlatform[A] {
    * @param policy
    *   the policy to use
    *
-   * @param onRetry
+   * @param onError
    *   the effect to invoke on every retry decision
    */
   def retry(
       policy: Retry[IO, Throwable],
-      onRetry: (Retry.Status, Throwable, Retry.Decision) => IO[Unit]
+      onError: (Retry.Status, Throwable, Retry.Decision) => IO[Unit]
   ): IO[A] =
-    Retry.retry(policy, onRetry)(this)
+    Retry.retry(policy, onError)(this)
 
   /**
    * Inverse of `attempt`

diff --git a/std/shared/src/main/scala/cats/effect/std/Retry.scala b/std/shared/src/main/scala/cats/effect/std/Retry.scala
@@ -486,17 +486,17 @@ object Retry {
    * @param policy
    *   the policy to use
    *
-   * @param onRetry
+   * @param onError
    *   the effect to invoke on every retry decision
    *
    * @param fa
    *   the effect
    */
   def retry[F[_], A, E](
       policy: Retry[F, E],
-      onRetry: (Status, E, Decision) => F[Unit]
+      onError: (Status, E, Decision) => F[Unit]
   )(fa: F[A])(implicit F: GenTemporal[F, E]): F[A] =
-    doRetry(policy, Some(onRetry))(fa)
+    doRetry(policy, Some(onError))(fa)
 
   /**
    * The return policy that always gives up.

diff --git a/std/shared/src/main/scala/cats/effect/std/syntax/RetrySyntax.scala b/std/shared/src/main/scala/cats/effect/std/syntax/RetrySyntax.scala
@@ -31,8 +31,8 @@ final class RetryOps[F[_], A] private[syntax] (private val fa: F[A]) extends Any
 
   def retry[E](
       policy: Retry[F, E],
-      onRetry: (Retry.Status, E, Retry.Decision) => F[Unit]
+      onError: (Retry.Status, E, Retry.Decision) => F[Unit]
   )(implicit F: GenTemporal[F, E]): F[A] =
-    Retry.retry(policy, onRetry)(fa)
+    Retry.retry(policy, onError)(fa)
 
 }
diff --git a/tests/shared/src/test/scala/cats/effect/std/RetrySpec.scala b/tests/shared/src/test/scala/cats/effect/std/RetrySpec.scala
@@ -17,8 +17,11 @@
 package cats.effect.std
 
 import cats.{Hash, Show}
-import cats.effect.{BaseSpec, IO, Ref}
+import cats.data.EitherT
+import cats.effect.{BaseSpec, IO, Ref, Temporal}
+import cats.mtl.Handle
 import cats.syntax.applicative._
+import cats.syntax.flatMap._
 import cats.syntax.functor._
 import cats.syntax.semigroup._
 
@@ -453,6 +456,112 @@ class RetrySpec extends BaseSpec {
 
   }
 
+  "Retry MTL" should {
+
+    sealed trait Errors
+    final class Error1 extends Errors
+    final class Error2 extends Errors
+
+    type RetryAttempt = (Status, Decision, Errors)
+
+    def mtlRetry[F[_], E, A](
+        action: F[A],
+        policy: Retry[F, E],
+        onRetry: (Status, E, Decision) => F[Unit]
+    )(implicit F: Temporal[F], H: Handle[F, E]): F[A] =
+      F.tailRecM(Status.initial) { status =>
+        H.attempt(action).flatMap {
+          case Left(error) =>
+            policy
+              .decide(status, error)
+              .flatTap(decision => onRetry(status, error, decision))
+              .flatMap {
+                case retry: Decision.Retry =>
+                  F.delayBy(F.pure(Left(status.withRetry(retry.delay))), retry.delay)
+
+                case _: Decision.GiveUp =>
+                  H.raise(error)
+              }
+
+          case Right(success) =>
+            F.pure(Right(success))
+        }
+      }
+
+    implicit val outputHash: Hash[(Either[Errors, Unit], List[RetryAttempt])] =
+      Hash.fromUniversalHashCode
+
+    implicit val outputShow: Show[(Either[Errors, Unit], List[RetryAttempt])] =
+      Show.fromToString
+
+    "give up on mismatched errors" in ticked { implicit ticker =>
+      type F[A] = EitherT[IO, Errors, A]
+
+      val maxRetries = 2
+      val delay = 1.second
+
+      val error = new Error2
+      val policy = Retry
+        .constantDelay[F, Errors](delay)
+        .withMaxRetries(maxRetries)
+        .withErrorMatcher(Retry.ErrorMatcher[F, Errors].only[Error1])
+
+      val expected: List[RetryAttempt] = List(
+        (Status(0, Duration.Zero), Decision.giveUp, error)
+      )
+
+      val io: F[Unit] = Handle[F, Errors].raise[Errors, Unit](error)
+
+      val run =
+        for {
+          ref <- IO.ref(List.empty[RetryAttempt])
+          result <- mtlRetry[F, Errors, Unit](
+            io,
+            policy,
+            (s, e: Errors, d) => EitherT.liftF(ref.update(_ :+ (s, d, e)))
+          ).value
+          attempts <- ref.get
+        } yield (result, attempts)
+
+      run must completeAs((Left(error), expected))
+    }
+
+    "retry only on matching errors" in ticked { implicit ticker =>
+      type F[A] = EitherT[IO, Errors, A]
+
+      val maxRetries = 2
+      val delay = 1.second
+
+      val error = new Error1
+      val policy = Retry
+        .constantDelay[F, Errors](delay)
+        .withMaxRetries(maxRetries)
+        .withErrorMatcher(Retry.ErrorMatcher[F, Errors].only[Error1])
+
+      val expected: List[RetryAttempt] = List(
+        (Status(0, Duration.Zero), Decision.retry(delay), error),
+        (Status(1, 1.second), Decision.retry(delay), error),
+        (Status(2, 2.seconds), Decision.giveUp, error)
+      )
+
+      val io: F[Unit] = Handle[F, Errors].raise[Errors, Unit](error)
+
+      val run =
+        for {
+          ref <- IO.ref(List.empty[RetryAttempt])
+          result <- mtlRetry[F, Errors, Unit](
+            io,
+            policy,
+            (s, e: Errors, d) => EitherT.liftF(ref.update(_ :+ (s, d, e)))
+          ).value
+          attempts <- ref.get
+        } yield (result, attempts)
+
+      run must completeAs((Left(error), expected))
+    }
+
+  }
+
   private def run[A](policy: Retry[IO, Throwable])(io: IO[A]): IO[List[RetryAttempt]] =
     for {
       ref <- IO.ref(List.empty[RetryAttempt])