Some enumerators

AdventOfCode2022.Test/AdventOfCode2022.Test.fsproj

@@ -8,6 +8,7 @@
 
     <ItemGroup>
         <Compile Include="Assembly.fs" />
+        <Compile Include="TestEnumerators.fs" />
         <Compile Include="Day1.fs" />
         <Compile Include="Day2.fs" />
         <Compile Include="Day3.fs" />

AdventOfCode2022.Test/TestEnumerators.fs

@@ -0,0 +1,57 @@
+namespace AdventOfCode2022.Test
+
+open System.Collections.Generic
+open AdventOfCode2022
+open NUnit.Framework
+open FsUnitTyped
+
+[<TestFixture>]
+module TestEnumerators =
+
+    [<Test>]
+    let ``MapEnumerator doesn't allocate`` () =
+        let original = seq { 1..100 }
+
+        let f (x : int) = byte x + 1uy
+
+        let enum = MapEnumerator.make f (original.GetEnumerator ())
+        //let foo = unbox<IEnumerator<byte>> (enum.GetEnumerator ())
+        //let enum = MapEnumerator.make<byte, byte> id foo
+
+        // Seq's GetEnumerator does allocate.
+        let bytesBefore = System.GC.GetAllocatedBytesForCurrentThread ()
+        let mutable expected = 2uy
+
+        for output in enum do
+            // shouldEqual allocates
+            if output <> expected then
+                failwithf "not equal, expected %i, actual %i" expected output
+
+            expected <- expected + 1uy
+
+        let bytesAfter = System.GC.GetAllocatedBytesForCurrentThread ()
+        bytesAfter |> shouldEqual bytesBefore
+
+
+    [<Test>]
+    let ``ChooseEnumerator doesn't allocate`` () =
+        let original = seq { 1..100 }
+
+        let enum =
+            ChooseEnumerator.make
+                (fun x -> let x = byte x + 1uy in if x % 2uy = 0uy then ValueSome x else ValueNone)
+                (original.GetEnumerator ())
+
+        let bytesBefore = System.GC.GetAllocatedBytesForCurrentThread ()
+
+        let mutable expected = 2uy
+
+        for output in enum do
+            // shouldEqual allocates
+            if output <> expected then
+                failwithf "not equal, expected %i, actual %i" expected output
+
+            expected <- expected + 2uy
+
+        let bytesAfter = System.GC.GetAllocatedBytesForCurrentThread ()
+        bytesAfter |> shouldEqual bytesBefore