Update Materialize tests to account for new optimization

polyadic · Nov 20, 2023 · 74385e6 · 74385e6
1 parent d651c4a
commit 74385e6
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Showing 4 changed files with 19 additions and 9 deletions.
diff --git a/Funcky.Test/Extensions/EnumerableExtensions/AnyOrElseTest.cs b/Funcky.Test/Extensions/EnumerableExtensions/AnyOrElseTest.cs
@@ -13,15 +13,15 @@ public void IsEmptyWhenBothEnumerablesAreEmpty()
     [Fact]
     public void IsSourceEnumerableWhenNonEmpty()
     {
-        var source = Sequence.Return(1, 2, 3).EraseNonEnumeratedCount();
+        var source = Sequence.Return(1, 2, 3).PreventLinqOptimizations();
         var fallback = Sequence.Return(4, 5, 6);
         Assert.Equal(source, source.AnyOrElse(fallback));
     }
 
     [Fact]
     public void IsFallbackEnumerableWhenSourceIsEmpty()
     {
-        var source = Enumerable.Empty<int>().EraseNonEnumeratedCount();
+        var source = Enumerable.Empty<int>().PreventLinqOptimizations();
         var fallback = Sequence.Return(1, 2, 3);
         Assert.Equal(fallback, source.AnyOrElse(fallback));
     }
@@ -36,7 +36,7 @@ public void SourceIsEnumeratedLazily()
     [Fact]
     public void FallbackIsEnumeratedLazily()
     {
-        var source = Enumerable.Empty<int>().EraseNonEnumeratedCount();
+        var source = Enumerable.Empty<int>().PreventLinqOptimizations();
         _ = source.AnyOrElse(new FailOnEnumerationSequence<int>());
     }
 

diff --git a/Funcky.Test/Extensions/EnumerableExtensions/GetNonEnumeratedCountOrNoneTest.cs b/Funcky.Test/Extensions/EnumerableExtensions/GetNonEnumeratedCountOrNoneTest.cs
@@ -28,7 +28,7 @@ public void GetNonEnumeratedCountOrNoneReturnsCountOnEnumerableRange()
     [Property]
     public Property GetNonEnumeratedCountOrNoneReturnsNoneForInstancesWithoutCount(List<int> list)
     {
-        return list.EraseNonEnumeratedCount().GetNonEnumeratedCountOrNone()
+        return list.PreventLinqOptimizations().GetNonEnumeratedCountOrNone()
             .Match(none: true, some: False)
             .ToProperty();
     }

diff --git a/Funcky.Test/Extensions/EnumerableExtensions/MaterializeTest.cs b/Funcky.Test/Extensions/EnumerableExtensions/MaterializeTest.cs
@@ -26,19 +26,30 @@ public void MaterializeDoesNotEnumerateCollectionTypes()
     [Fact]
     public void MaterializeReturnsImmutableCollectionWhenEnumerated()
     {
-        var sequence = Enumerable.Repeat("Hello world!", 3);
+        var sequence = Enumerable.Repeat("Hello world!", 3).PreventLinqOptimizations();
 
         Assert.IsType<ImmutableList<string>>(sequence.Materialize());
     }
 
     [Fact]
     public void MaterializeWithMaterializationReturnsCorrectCollectionWhenEnumerate()
     {
-        var sequence = Enumerable.Repeat("Hello world!", 3);
+        var sequence = Enumerable.Repeat("Hello world!", 3).PreventLinqOptimizations();
 
         Assert.IsType<HashSet<string>>(sequence.Materialize(ToHashSet));
     }
 
+#if NET8_0_OR_GREATER
+    // This is an optimization added in .NET 8
+    [Fact]
+    public void MaterializeDoesNotEnumerableEnumerableReturnedByRepeat()
+    {
+        var sequence = Enumerable.Repeat("Hello world!", 3);
+        var materialized = sequence.Materialize<string, IReadOnlyCollection<string>>(_ => throw new FailException("Materialization should never be called"));
+        Assert.Same(sequence, materialized);
+    }
+#endif
+
     [Fact]
     public void MaterializeDoesNotEnumerateCollectionWhichImplementsICollectionOnly()
     {

diff --git a/Funcky.Test/TestUtils/EnumerableExtensions.cs b/Funcky.Test/TestUtils/EnumerableExtensions.cs
@@ -2,10 +2,9 @@ namespace Funcky.Test.TestUtils;
 
 internal static class EnumerableExtensions
 {
-    internal static IEnumerable<TItem> EraseNonEnumeratedCount<TItem>(this IEnumerable<TItem> source)
+    /// <summary>Prevents LINQ from optimizing by hiding the underlying source enumerable.</summary>
+    internal static IEnumerable<TItem> PreventLinqOptimizations<TItem>(this IEnumerable<TItem> source)
     {
-        // Having our own state machine erases the non enumerated count
-        // provided when using LINQ methods such as Select.
         foreach (var element in source)
         {
             yield return element;