Improve LOH memory checks in release buffer tests

Refined UsingMemoryStreamSlimReleaseBuffers test logic to assert LOH memory usage only on the first loop and to return early if LOH memory drops to zero after GC or buffer release. This makes the test more robust and prevents false failures when memory is released as expected.

Author: kzdev-net

Source/Tst/KZDev.PerfUtils.Memory.Heap.Sequential.UnitTests/UsingMemoryStreamSlimReleaseBuffers.cs

@@ -59,11 +59,20 @@ public void UsingMemoryStreamSlimReleaseBuffers_CopyFullToStream_SettingReleaseM
                 using MemoryStreamSlim testService = MemoryStreamSlim.Create(options => options.WithZeroBufferBehavior(MemoryStreamSlimZeroBufferOption.OnRelease));
                 int byteCount = testDataSizes[RandomSource.GetRandomInteger(testDataSizes.Length)];
                 MemoryTestPrep.FillStreamAndArrayWithRandomBytes(testService, byteCount, testSegmentSize);
+                // Make sure that the LOH memory usage is non-zero on the first loop.
+                if (testLoop > 0)
+                    continue;
+                testMetricsMonitor.LohSize.Should().BeGreaterThan(0);
             }
 
         // Clean the GC and capture the current LOH memory usage
         GC.Collect(GC.MaxGeneration);
         double runCompleteLohMemory = testMetricsMonitor.LohSize;
+        if (runCompleteLohMemory == 0)
+        {
+            // We know that LOH did go above zero during the test, so if it is back to zero now then we can just end the test since the memory was released as expected.
+            return;
+        }
         // Tell the MemoryStreamSlim to release its memory buffers
         MemoryStreamSlim.ReleaseMemoryBuffers();
 
@@ -74,6 +83,10 @@ public void UsingMemoryStreamSlimReleaseBuffers_CopyFullToStream_SettingReleaseM
         GC.Collect(GC.MaxGeneration);
         // We should drop LOH memory by at least 1/2 (it should actually drop to zero, but we can't guarantee that)
         double newLohMemory = testMetricsMonitor.LohSize;
+        if (newLohMemory == 0)
+        {
+            return;
+        }
         newLohMemory.Should().BeLessThan(runCompleteLohMemory / 2);
     }
     //--------------------------------------------------------------------------------