Initial commit.

PerfectNumbers.Core.Tests/Gpu/GpuPrimeLimiterTests.cs

@@ -0,0 +1,45 @@
+using System.Diagnostics;
+using FluentAssertions;
+using PerfectNumbers.Core.Gpu;
+using Xunit;
+
+namespace PerfectNumbers.Core.Tests.Gpu;
+
+[Collection("GpuNtt")]
+[Trait("Category", "Fast")]
+public class GpuPrimeLimiterTests
+{
+    [Fact]
+    public async Task Acquire_blocks_when_limit_reached()
+    {
+        // Ensure limit = 1 so second acquire must wait.
+        GpuPrimeWorkLimiter.SetLimit(1);
+
+        var startedSecond = new TaskCompletionSource<bool>();
+        var sw = new Stopwatch();
+
+        using var first = GpuPrimeWorkLimiter.Acquire();
+        sw.Start();
+
+        var secondTask = Task.Run(() =>
+        {
+            using var second = GpuPrimeWorkLimiter.Acquire();
+            startedSecond.TrySetResult(true);
+        });
+
+        // Give secondTask a moment to attempt acquire (it should block).
+        await Task.Delay(50);
+        startedSecond.Task.IsCompleted.Should().BeFalse();
+
+        // Release first after short delay, allowing second to continue.
+        // (Dispose at scope end, but we want to end now.)
+        first.Dispose();
+
+        await secondTask.WaitAsync(TimeSpan.FromSeconds(1));
+        sw.Stop();
+
+        // Should be > ~50ms because second had to wait for first to release.
+        sw.ElapsedMilliseconds.Should().BeGreaterThanOrEqualTo(50);
+    }
+}
+