Let ResolveGitObject resolve commit without path

This will let us give user more meaningful warnings.

Author: jcansdale

src/GitHub.App/Services/GitHubContextService.cs

@@ -14,7 +14,6 @@
 using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Shell.Interop;
 using Microsoft.VisualStudio.TextManager.Interop;
-using LibGit2Sharp;
 
 namespace GitHub.App.Services
 {
@@ -322,11 +321,19 @@ public string ResolvePath(GitHubContext context)
 
                 foreach (var objectish in ToObjectish(objectishPath))
                 {
-                    var gitObject = repository.Lookup($"{objectish.commitish}:{objectish.path}");
-                    if (gitObject != null)
+                    var commit = repository.Lookup(objectish.commitish);
+                    if (commit == null)
                     {
-                        return objectish;
+                        continue;
                     }
+
+                    var blob = repository.Lookup($"{objectish.commitish}:{objectish.path}");
+                    if (blob == null)
+                    {
+                        return (objectish.commitish, null);
+                    }
+
+                    return objectish;
                 }
 
                 return (null, null);

test/GitHub.App.UnitTests/Services/GitHubContextServiceTests.cs

@@ -325,24 +325,27 @@ public void RepositoryHome(string windowTitle, string expectOwner, string expect
 
     public class TheResolveGitObjectMethod
     {
-        [TestCase("https://github.com/github/VisualStudio/blob/master/foo.cs", "master:foo.cs", "master", "foo.cs")]
-        [TestCase("https://github.com/github/VisualStudio/blob/master/src/foo.cs", "master:src/foo.cs", "master", "src/foo.cs")]
-        [TestCase("https://github.com/github/VisualStudio/blob/branch-name/src/foo.cs", "branch-name:src/foo.cs", "branch-name", "src/foo.cs")]
-        [TestCase("https://github.com/github/VisualStudio/blob/fixes/666-bug/src/foo.cs", "fixes/666-bug:src/foo.cs", "fixes/666-bug", "src/foo.cs")]
-        [TestCase("https://github.com/github/VisualStudio/blob/fixes/666-bug/A/B/foo.cs", "fixes/666-bug:A/B/foo.cs", "fixes/666-bug", "A/B/foo.cs")]
-        public void ResolveGitObject(string url, string treeish, string expectCommitish, string expectPath)
+        [TestCase("https://github.com/github/VisualStudio/blob/master/foo.cs", "master", "master:foo.cs", "master", "foo.cs")]
+        [TestCase("https://github.com/github/VisualStudio/blob/master/src/foo.cs", "master", "master:src/foo.cs", "master", "src/foo.cs")]
+        [TestCase("https://github.com/github/VisualStudio/blob/branch-name/src/foo.cs", "branch-name", "branch-name:src/foo.cs", "branch-name", "src/foo.cs")]
+        [TestCase("https://github.com/github/VisualStudio/blob/fixes/666-bug/src/foo.cs", "fixes/666-bug", "fixes/666-bug:src/foo.cs", "fixes/666-bug", "src/foo.cs")]
+        [TestCase("https://github.com/github/VisualStudio/blob/fixes/666-bug/A/B/foo.cs", "fixes/666-bug", "fixes/666-bug:A/B/foo.cs", "fixes/666-bug", "A/B/foo.cs")]
+        [TestCase("https://github.com/github/VisualStudio/blob/master/foo.cs", "master", "", "master", null, Description = "Resolve commit only")]
+        public void ResolveGitObject(string url, string commitish, string objectish, string expectCommitish, string expectPath)
         {
             var repositoryDir = "repositoryDir";
             var repository = Substitute.For<IRepository>();
-            var expectGitObject = Substitute.For<GitObject>();
-            repository.Lookup(treeish).Returns(expectGitObject);
+            var commit = Substitute.For<Commit>();
+            var blob = Substitute.For<Blob>();
+            repository.Lookup(commitish).Returns(commit);
+            repository.Lookup(objectish).Returns(blob);
             var target = CreateGitHubContextService(repositoryDir, repository);
             var context = target.FindContextFromUrl(url);
 
-            var (commitish, path) = target.ResolveGitObject(repositoryDir, context);
+            var (resolvedCommitish, resolvedPath) = target.ResolveGitObject(repositoryDir, context);
 
-            Assert.That(commitish, Is.EqualTo(expectCommitish));
-            Assert.That(path, Is.EqualTo(expectPath));
+            Assert.That(resolvedCommitish, Is.EqualTo(expectCommitish));
+            Assert.That(resolvedPath, Is.EqualTo(expectPath));
         }
     }