Add first test case for referencing and running Exe project

See dotnet#1675

Author: dsplaisted

src/Tests/Microsoft.NET.Build.Tests/ReferenceExeTests.cs

@@ -0,0 +1,81 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.IO;
+using System.Linq;
+using System.Xml.Linq;
+using FluentAssertions;
+using Microsoft.DotNet.Cli.Utils;
+using Microsoft.NET.TestFramework;
+using Microsoft.NET.TestFramework.Assertions;
+using Microsoft.NET.TestFramework.Commands;
+using Microsoft.NET.TestFramework.ProjectConstruction;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Microsoft.NET.Build.Tests
+{
+    public class ReferenceExeTests : SdkTest
+    {
+        public ReferenceExeTests(ITestOutputHelper log) : base(log)
+        {
+        }
+
+        [Fact]
+        public void ReferencedExeCanRun()
+        {
+            var mainProject = new TestProject()
+            {
+                Name = "MainProject",
+                TargetFrameworks = "net5.0",
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            mainProject.SourceFiles["Program.cs"] = @"System.Console.WriteLine(""Main Project"");";
+
+            var referencedProject = new TestProject()
+            {
+                Name = "ReferencedProject",
+                TargetFrameworks = "net5.0",
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            referencedProject.SourceFiles["Program.cs"] = @"System.Console.WriteLine(""Referenced Project"");";
+
+            mainProject.ReferencedProjects.Add(referencedProject);
+
+            var testProjectInstance = _testAssetsManager.CreateTestProject(mainProject);
+
+            var buildCommand = new BuildCommand(testProjectInstance);
+
+            buildCommand.Execute()
+                .Should()
+                .Pass();
+
+            var outputDirectory = buildCommand.GetOutputDirectory(mainProject.TargetFrameworks);
+
+            var mainExePath = Path.Combine(outputDirectory.FullName, mainProject.Name + Constants.ExeSuffix);
+
+            var referencedExePath = Path.Combine(outputDirectory.FullName, referencedProject.Name + Constants.ExeSuffix);
+
+            new RunExeCommand(Log, mainExePath)
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .HaveStdOut("Main Project");
+
+
+            new RunExeCommand(Log, referencedExePath)
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .HaveStdOut("Referenced Project");
+
+        }
+    }
+}