Fix System.String[] sometimes printing in unit tests

src/Tools/Source/RunTests/TestRunner.cs

@@ -148,8 +148,8 @@ private async Task<TestResult> RunTest(string assemblyPath, CancellationToken ca
                 bool noResultsData = (all.Length == 0);
                 if (noResultsData)
                 {
-                    var output = processOutput.OutputLines.Concat(processOutput.ErrorLines).ToArray();
-                    Console.Write(output);
+                    var output = processOutput.OutputLines.Concat(processOutput.ErrorLines);
+                    Console.Write(string.Join(Environment.NewLine, output));
 
                     // Delete the output file.
                     File.Delete(resultsPath);