diagnose: add GitHub API diagnostic tests

Author: mjcheetham

src/shared/GitHub/Diagnostics/GitHubApiDiagnostic.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Git.CredentialManager.Diagnostics;
+
+namespace GitHub.Diagnostics
+{
+    public class GitHubApiDiagnostic : Diagnostic
+    {
+        private readonly IGitHubRestApi _api;
+
+        public GitHubApiDiagnostic(IGitHubRestApi api)
+            : base("GitHub API")
+        {
+            _api = api;
+        }
+
+        protected override async Task<bool> RunInternalAsync(StringBuilder log, IList<string> additionalFiles)
+        {
+            var targetUri = new Uri("https://github.com");
+            log.AppendLine($"Using '{targetUri}' as API target.");
+
+            log.Append("Querying '/meta' endpoint...");
+            GitHubMetaInfo metaInfo = await _api.GetMetaInfoAsync(targetUri);
+            log.AppendLine(" OK");
+
+            return true;
+        }
+    }
+}

src/shared/GitHub/GitHubHostProvider.cs

@@ -2,12 +2,14 @@
 using System.Collections.Generic;
 using System.Net.Http;
 using System.Threading.Tasks;
+using GitHub.Diagnostics;
 using Microsoft.Git.CredentialManager;
 using Microsoft.Git.CredentialManager.Authentication.OAuth;
+using Microsoft.Git.CredentialManager.Diagnostics;
 
 namespace GitHub
 {
-    public class GitHubHostProvider : HostProvider
+    public class GitHubHostProvider : HostProvider, IDiagnosticProvider
     {
         private static readonly string[] GitHubOAuthScopes =
         {
@@ -295,6 +297,11 @@ protected override void ReleaseManagedResources()
             base.ReleaseManagedResources();
         }
 
+        public IEnumerable<IDiagnostic> GetDiagnostics()
+        {
+            yield return new GitHubApiDiagnostic(_gitHubApi);
+        }
+
         #region Private Methods
 
         public static bool IsGitHubDotCom(string targetUrl)