Fix outerloop System.Buffers tests after s_trimBuffers removal (#56068)

We deleted this switch.  Turns out there were outerloop tests looking for it.

src/libraries/System.Buffers/tests/ArrayPool/ArrayPoolTest.cs

@@ -10,8 +10,6 @@ namespace System.Buffers.ArrayPool.Tests
 {
     public abstract class ArrayPoolTest
     {
-        protected const string TrimSwitchName = "DOTNET_SYSTEM_BUFFERS_ARRAYPOOL_TRIMSHARED";
-
         protected static class EventIds
         {
             public const int BufferRented = 1;
@@ -35,26 +33,16 @@ protected static int RunWithListener(Action body, EventLevel level, Action<Event
             }
         }
 
-        protected static void RemoteInvokeWithTrimming(Action action, bool trim = false)
-        {
-            RemoteInvokeOptions options = new RemoteInvokeOptions();
-            options.StartInfo.UseShellExecute = false;
-            options.StartInfo.EnvironmentVariables.Add(TrimSwitchName, trim.ToString());
-
-            RemoteExecutor.Invoke(action).Dispose();
-        }
-
-        protected static void RemoteInvokeWithTrimming(Action<string> method, bool trim = false, int timeout = RemoteExecutor.FailWaitTimeoutMilliseconds)
+        protected static void RemoteInvokeWithTrimming(Action method, int timeout = RemoteExecutor.FailWaitTimeoutMilliseconds)
         {
             var options = new RemoteInvokeOptions
             {
                 TimeOut = timeout
             };
 
             options.StartInfo.UseShellExecute = false;
-            options.StartInfo.EnvironmentVariables.Add(TrimSwitchName, trim.ToString());
 
-            RemoteExecutor.Invoke(method, trim.ToString(), options).Dispose();
+            RemoteExecutor.Invoke(method, options).Dispose();
         }
     }
 }

src/libraries/System.Buffers/tests/ArrayPool/CollectionTests.cs

@@ -15,22 +15,16 @@ namespace System.Buffers.ArrayPool.Tests
     public class CollectionTests : ArrayPoolTest
     {
         [OuterLoop("This is a long running test (over 2 minutes)")]
-        [ConditionalTheory(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported)),
-            InlineData(true),
-            InlineData(false)]
-        public void BuffersAreCollectedWhenStale(bool trim)
+        [ConditionalFact(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
+        public void BuffersAreCollectedWhenStale()
         {
-            RemoteInvokeWithTrimming((trimString) =>
+            RemoteInvokeWithTrimming(() =>
             {
-                // Check that our environment is as we expect
-                Assert.Equal(trimString, Environment.GetEnvironmentVariable(TrimSwitchName));
-
                 const int BufferCount = 8;
                 const int BufferSize = 1025;
 
                 // Get the pool and check our trim setting
                 var pool = ArrayPool<int>.Shared;
-                bool parsedTrim = ValidateTrimState(pool, trimString);
 
                 List<int[]> rentedBuffers = new List<int[]>();
 
@@ -71,27 +65,21 @@ public void BuffersAreCollectedWhenStale(bool trim)
                 }
 
                 // Should only have found a new buffer if we're trimming
-                Assert.Equal(parsedTrim, foundNewBuffer);
-            }, trim, 3 * 60 * 1000); // This test has to wait for the buffers to go stale (give it three minutes)
+                Assert.True(foundNewBuffer);
+            }, 3 * 60 * 1000); // This test has to wait for the buffers to go stale (give it three minutes)
         }
 
         private static bool IsStressModeEnabledAndRemoteExecutorSupported => TestEnvironment.IsStressModeEnabled && RemoteExecutor.IsSupported;
 
         // This test can cause problems for other tests run in parallel (from other assemblies) as
         // it pushes the physical memory usage above 80% temporarily.
-        [ConditionalTheory(nameof(IsStressModeEnabledAndRemoteExecutorSupported)),
-            InlineData(true),
-            InlineData(false)]
-        public unsafe void ThreadLocalIsCollectedUnderHighPressure(bool trim)
+        [ConditionalFact(nameof(IsStressModeEnabledAndRemoteExecutorSupported))]
+        public unsafe void ThreadLocalIsCollectedUnderHighPressure()
         {
-            RemoteInvokeWithTrimming((trimString) =>
+            RemoteInvokeWithTrimming(() =>
             {
-                // Check that our environment is as we expect
-                Assert.Equal(trimString, Environment.GetEnvironmentVariable(TrimSwitchName));
-
                 // Get the pool and check our trim setting
                 var pool = ArrayPool<byte>.Shared;
-                bool parsedTrim = ValidateTrimState(pool, trimString);
 
                 // Create our buffer, return it, re-rent it and ensure we have the same one
                 const int BufferSize = 4097;
@@ -119,40 +107,21 @@ public unsafe void ThreadLocalIsCollectedUnderHighPressure(bool trim)
                 } while ((int)pressureMethod.Invoke(null, null) != 2);
 
                 GC.WaitForPendingFinalizers();
-                if (parsedTrim)
-                {
-                    // Should have a new buffer now
-                    Assert.NotSame(buffer, pool.Rent(BufferSize));
-                }
-                else
-                {
-                    // Disabled, should not have trimmed buffer
-                    Assert.Same(buffer, pool.Rent(BufferSize));
-                }
-            }, trim);
-        }
 
-        private static bool ValidateTrimState(object pool, string trimString)
-        {
-            Assert.StartsWith("TlsOverPerCoreLockedStacksArrayPool", pool.GetType().Name);
-            bool parsedTrim = bool.Parse(trimString);
-            var trimField = pool.GetType().GetField("s_trimBuffers", BindingFlags.Static | BindingFlags.NonPublic);
-            Assert.Equal(parsedTrim, (bool)trimField.GetValue(null));
-            return parsedTrim;
+                // Should have a new buffer now
+                Assert.NotSame(buffer, pool.Rent(BufferSize));
+            });
         }
 
         private static bool IsPreciseGcSupportedAndRemoteExecutorSupported => PlatformDetection.IsPreciseGcSupported && RemoteExecutor.IsSupported;
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/44037")]
-        [ConditionalTheory(nameof(IsPreciseGcSupportedAndRemoteExecutorSupported))]
-        [InlineData(true)]
-        [InlineData(false)]
-        public void PollingEventFires(bool trim)
+        [ConditionalFact(nameof(IsPreciseGcSupportedAndRemoteExecutorSupported))]
+        public void PollingEventFires()
         {
-            RemoteInvokeWithTrimming((trimString) =>
+            RemoteInvokeWithTrimming(() =>
             {
                 var pool = ArrayPool<float>.Shared;
-                bool parsedTrim = ValidateTrimState(pool, trimString);
                 bool pollEventFired = false;
                 var buffer = pool.Rent(10);
 
@@ -187,8 +156,8 @@ public void PollingEventFires(bool trim)
                 });
 
                 // Polling events should only fire when trimming is enabled
-                Assert.Equal(parsedTrim, pollEventFired);
-            }, trim);
+                Assert.True(pollEventFired);
+            });
         }
     }
 }

src/libraries/System.Buffers/tests/ArrayPool/UnitTests.cs

@@ -355,7 +355,6 @@ public static void RentingGiganticArraySucceeds(int length, bool expectPooled)
         {
             var options = new RemoteInvokeOptions();
             options.StartInfo.UseShellExecute = false;
-            options.StartInfo.EnvironmentVariables.Add(TrimSwitchName, "false");
 
             RemoteExecutor.Invoke((lengthStr, expectPooledStr) =>
             {