Check we don't reference DesignTime assemblies

Check that no GitHub assemblies reference any assembly that ends with
DesignTime. Types from DesignTime assemblies should be embedded not
referenced.

Author: jcansdale

test/GitHub.VisualStudio.UnitTests/GitHubAssemblyTests.cs

@@ -0,0 +1,22 @@
+using System.IO;
+using System.Reflection;
+using NUnit.Framework;
+
+public class GitHubAssemblyTests
+{
+    [Theory]
+    public void GitHub_Assembly_Should_Not_Reference_DesignTime_Assembly(string assemblyFile)
+    {
+        var asm = Assembly.LoadFrom(assemblyFile);
+        foreach (var referencedAssembly in asm.GetReferencedAssemblies())
+        {
+            Assert.That(referencedAssembly.Name, Does.Not.EndWith(".DesignTime"),
+                "DesignTime assemblies should be embedded not referenced");
+        }
+    }
+
+    [DatapointSource]
+    string[] GitHubAssemblies => Directory.GetFiles(AssemblyDirectory, "GitHub.*.dll");
+
+    string AssemblyDirectory => Path.GetDirectoryName(GetType().Assembly.Location);
+}