From 8cc63d78d08367d078a3b48b8e1303011af4a6c5 Mon Sep 17 00:00:00 2001
From: Jacob Wang <jatcwang@gmail.com>
Date: Wed, 3 Jul 2024 12:47:38 +0100
Subject: [PATCH] Specilized API for IO (#7)

* Specilized API for IO

* Use IOCatch.apply instead of ioCatching. Revert rename of ioCatch (kept the val)

* Add headers

* Update uncancelable test to handle race-y condition

* fmt

* headers for test file

* fix warnings
---
 .../src/main/scala/catcheffect/Catch.scala    |  2 +-
 .../src/main/scala/catcheffect/IOCatch.scala  | 34 ++++++++
 .../test/scala/catcheffect/IOCatchTest.scala  | 81 +++++++++++++++++++
 3 files changed, 116 insertions(+), 1 deletion(-)
 create mode 100644 modules/core/src/main/scala/catcheffect/IOCatch.scala
 create mode 100644 modules/core/src/test/scala/catcheffect/IOCatchTest.scala

diff --git a/modules/core/src/main/scala/catcheffect/Catch.scala b/modules/core/src/main/scala/catcheffect/Catch.scala
index 9b00165..3d997da 100644
--- a/modules/core/src/main/scala/catcheffect/Catch.scala
+++ b/modules/core/src/main/scala/catcheffect/Catch.scala
@@ -222,7 +222,7 @@ object Catch {
           |The handler was defined at $alloc""".stripMargin
   }
 
-  def ioCatch: IO[Catch[IO]] =
+  val ioCatch: IO[Catch[IO]] =
     LocalForIOLocal
       .localForIOLocalDefault(Vault.empty)
       .map(implicit loc => fromLocal[IO])
diff --git a/modules/core/src/main/scala/catcheffect/IOCatch.scala b/modules/core/src/main/scala/catcheffect/IOCatch.scala
new file mode 100644
index 0000000..d69fc37
--- /dev/null
+++ b/modules/core/src/main/scala/catcheffect/IOCatch.scala
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2024 Valdemar Grange
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package catcheffect
+
+import Catch.ioCatch
+import cats.effect.*
+
+object IOCatch {
+
+  def apply[E]: IOCatchPartiallyApplied[E] =
+    new IOCatchPartiallyApplied[E]
+
+  class IOCatchPartiallyApplied[E] {
+    def apply[A](f: Handle[IO, E] => IO[A]): IO[Either[E, A]] = {
+      ioCatch.flatMap { c =>
+        c.use[E](f)
+      }
+    }
+  }
+
+}
diff --git a/modules/core/src/test/scala/catcheffect/IOCatchTest.scala b/modules/core/src/test/scala/catcheffect/IOCatchTest.scala
new file mode 100644
index 0000000..139574a
--- /dev/null
+++ b/modules/core/src/test/scala/catcheffect/IOCatchTest.scala
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2024 Valdemar Grange
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package catcheffect
+
+import catcheffect.Catch.{RaisedInUncancellable, RaisedWithoutHandler}
+import cats.effect.*
+import munit.CatsEffectSuite
+
+class IOCatchTest extends CatsEffectSuite {
+  test("should abort execution as soon as raise is called") {
+    for {
+      ref <- Ref[IO].of("init")
+      res <- IOCatch[String](h =>
+        for {
+          _ <- h.raise("error").void
+          _ <- ref.set("should not be set")
+        } yield 1
+      )
+      _ = assertEquals(res, Left("error"))
+      _ <- assertIO(ref.get, "init")
+    } yield ()
+  }
+
+  test("can nest correctly") {
+    for {
+      res <- IOCatch[String](hs1 =>
+        for {
+          _ <- IOCatch[String](_ => hs1.raise("1"))
+          _ <- IO.raiseError(new AssertionError("should not reach this point")).void
+        } yield ()
+      )
+      _ = assertEquals(res, Left("1"))
+    } yield res
+  }
+
+  test("Raising in an uncancellable region may correctly raise the error or throw RaisedInUncancellable") {
+    // There's a small race condition where cancellation from outside will win against the IO.cancel call,
+    // therefore RaisedInUncancellable isn't thrown. Unfortunately it doesn't seem like we can detect
+    // whether the current scope is cancellable without actually triggering cancellation
+    (for {
+      res <- IOCatch[String](h => IO.uncancelable(_ => h.raise("oops").void))
+      // If it did raise error instead of throwing RaisedInUncancellable, at least make sure it's raised correctly
+      _ = assertEquals(res, Left("oops"))
+    } yield ()).recoverWith {
+      case _: RaisedInUncancellable[_] => IO.unit // succeed
+      case e                           => IO.raiseError(e)
+    }
+  }
+
+  test("Can raise in an cancellable region when polled") {
+    for {
+      res <- IOCatch[String](h => IO.uncancelable(poll => poll(h.raise("oops"))))
+      _ = assertEquals(res, Left("oops"))
+    } yield ()
+  }
+
+  test("Fail to raise if the Raise instance is used outside of its original fiber") {
+    (for {
+      cached <- Deferred[IO, Raise[IO, String]]
+      res <- IOCatch[String](h => cached.complete(h).void)
+      _ = assertEquals(res, Right(()))
+      _ <- cached.get.flatMap(_.raise("hm")).void
+    } yield ()).attempt.map {
+      case Left(_: RaisedWithoutHandler[_]) => () // succeed
+      case other                            => fail(s"Expected RaisedWithoutHandler, got $other")
+    }
+  }
+}