Made logging during test runs configurable via an environment variable.

Author: rstam

build/build.fsx

@@ -133,7 +133,7 @@ Target "Test" (fun _ ->
             { p with 
                 OutputFile = testResultsDir @@ getBuildParamOrDefault "testResults" "test-results.xml"
                 DisableShadowCopy = true
-                ShowLabels = true
+                ShowLabels = Environment.GetEnvironmentVariable("MONGO_LOGGING") <> null
                 Framework = !framework
                 IncludeCategory = getBuildParamOrDefault "testInclude" ""
                 ExcludeCategory = getBuildParamOrDefault "testExclude" ""

src/MongoDB.Driver.Core.TestHelpers/CoreTestConfiguration.cs

@@ -121,7 +121,19 @@ public static ClusterBuilder ConfigureCluster(ClusterBuilder builder)
 
         public static ClusterBuilder ConfigureLogging(ClusterBuilder builder)
         {
-            var traceSource = new TraceSource("mongodb-tests", SourceLevels.Verbose);
+            var environmentVariable = Environment.GetEnvironmentVariable("MONGO_LOGGING");
+            if (environmentVariable == null)
+            {
+                return builder;
+            }
+
+            SourceLevels defaultLevel;
+            if (!Enum.TryParse<SourceLevels>(environmentVariable, ignoreCase: true, result: out defaultLevel))
+            {
+                return builder;
+            }
+
+            var traceSource = new TraceSource("mongodb-tests", defaultLevel);
             traceSource.Listeners.Clear(); // remove the default listener
             var listener = new ConsoleTraceListener();
             listener.TraceOutputOptions = TraceOptions.DateTime;