Added a command line arg for not inducing any GCs while running Benchmarks (#2101)

Author: mrsharm

src/BenchmarkDotNet/ConsoleArguments/CommandLineOptions.cs

@@ -209,6 +209,9 @@ public bool UseDisassemblyDiagnoser
         [Option("wasmDataDir", Required = false, HelpText = "Wasm data directory")]
         public DirectoryInfo WasmDataDirectory { get; set; }
 
+        [Option("noForcedGCs", Required = false, HelpText = "Specifying would not forcefully induce any GCs.")]
+        public bool NoForcedGCs { get; set; }
+
         internal bool UserProvidedFilters => Filters.Any() || AttributeNames.Any() || AllCategories.Any() || AnyCategories.Any();
 
         [Usage(ApplicationAlias = "")]

src/BenchmarkDotNet/ConsoleArguments/ConfigParser.cs

@@ -294,6 +294,8 @@ private static Job GetBaseJob(CommandLineOptions options, IConfig globalConfig)
                 baseJob = baseJob.RunOncePerIteration();
             if (options.MemoryRandomization)
                 baseJob = baseJob.WithMemoryRandomization();
+            if (options.NoForcedGCs)
+                baseJob = baseJob.WithGcForce(false);
 
             if (options.EnvironmentVariables.Any())
             {

tests/BenchmarkDotNet.Tests/ConfigParserTests.cs

@@ -560,5 +560,17 @@ public void InvalidEnvVarAreRecognized()
         {
             Assert.False(ConfigParser.Parse(new[] { "--envVars", "INVALID_NO_SEPARATOR" }, new OutputLogger(Output)).isSuccess);
         }
+
+        [Fact]
+        public void UserCanSpecifyNoForceGCs()
+        {
+            var parsedConfiguration = ConfigParser.Parse(new[] { "--noForcedGCs" }, new OutputLogger(Output));
+            Assert.True(parsedConfiguration.isSuccess);
+
+            foreach (var job in parsedConfiguration.config.GetJobs())
+            {
+                Assert.False(job.Environment.Gc.Force);
+            }
+        }
     }
 }