Move command line parsing into try/catch for test.

If invalid parameters are specified in `dotnet test`, the CLI does not
catch exceptions that can be thrown such as when specifying `-r` without
a runtime.

Fixes 3084.

src/dotnet/commands/dotnet-test/Program.cs

@@ -26,10 +26,10 @@ namespace Microsoft.DotNet.Tools.Test
 
             var dotnetTestParams = new DotnetTestParams();
 
-            dotnetTestParams.Parse(args);
-
             try
             {
+                dotnetTestParams.Parse(args);
+            
                 if (dotnetTestParams.Help)
                 {
                     return 0;

test/dotnet-test.Tests/GivenThatWeWantToRunTests.cs

@@ -25,5 +25,19 @@ namespace Microsoft.Dotnet.Tools.Test.Tests
                 .And
                 .HaveStdErrContaining("dotnet restore");
         }
+        
+        [Fact]
+        public void It_fails_correctly_with_invalid_runtime_parameter()
+        {
+            var instance = TestAssetsManager.CreateTestInstance(Path.Combine("ProjectsWithTests", "NetCoreAppOnlyProject"));
+
+            new DotnetTestCommand()
+                .WithLockFiles()
+                .ExecuteWithCapturedOutput(instance.TestRoot)
+                .Should()
+                .Fail()
+                .And
+                .HaveStdErrContaining("Missing value for option 'runtime'");
+        }
     }
 }