Add kestrel tests.

Tests will 'build', 'run', 'publish' and 'execute' a Kestrel Hello World server as a PortableFatApp and as a Standalone app.

test/Kestrel.Tests/DotnetBuildTest.cs

@@ -0,0 +1,48 @@
+using System.IO;
+using Microsoft.DotNet.Tools.Test.Utilities;
+using Xunit;
+using Microsoft.DotNet.TestFramework;
+
+namespace Microsoft.DotNet.Kestrel.Tests
+{
+    public class DotnetBuildTest : TestBase
+    {
+        public static string KestrelPortableApp { get; } = "KestrelPortable";
+
+        [Fact]
+        public void BuildingKestrelPortableFatAppProducesExpectedArtifacts()
+        {
+            var testInstance = TestAssetsManager.CreateTestInstance("KestrelSample")
+                .WithLockFiles();
+
+            BuildAndTest(Path.Combine(testInstance.TestRoot, KestrelPortableApp));
+        }
+
+        private static void BuildAndTest(string testRoot)
+        {
+            string appName = Path.GetFileName(testRoot);
+
+
+            var result = new BuildCommand(
+                projectPath: testRoot)
+                .ExecuteWithCapturedOutput();
+
+            result.Should().Pass();
+
+            var outputBase = new DirectoryInfo(Path.Combine(testRoot, "bin", "Debug"));
+
+            var netstandardappOutput = outputBase.Sub("netstandard1.5");
+
+            netstandardappOutput.Should()
+                .Exist().And
+                .OnlyHaveFiles(new[]
+                {
+                    $"{appName}.deps.json",
+                    $"{appName}.dll",
+                    $"{appName}.pdb",
+                    $"{appName}.runtimeconfig.json",
+                    $"{appName}.runtimeconfig.dev.json"
+                });
+        }
+    }
+}