Add tests for invoking dotnet XX project.json from in

a folder that contains the project.

test/dotnet-run.Tests/RunTests.cs

@@ -68,6 +68,21 @@ namespace Microsoft.DotNet.Tools.Run.Tests
             new RunCommand(instance.TestRoot).Execute().Should().Pass();
         }
 
+        [Fact]
+        public void ItRunsWithLocalProjectJsonArg()
+        {
+            TestInstance instance = TestAssetsManager.CreateTestInstance("TestAppSimple")
+                                                     .WithLockFiles()
+                                                     .WithBuildArtifacts();
+            new RunCommand("project.json")
+                .WithWorkingDirectory(instance.TestRoot)
+                .ExecuteWithCapturedOutput()
+                .Should()
+                .Pass()
+                .And
+                .HaveStdOutContaining("Hello World!");
+        }
+
         [Fact]
         public void ItRunsAppsThatOutputUnicodeCharacters()
         {