Ensure Tags can be created in detached Head state

Fix #791

3 files changed, 25 insertions, 4 deletions

diff --git a/LibGit2Sharp.Tests/ResetHeadFixture.cs b/LibGit2Sharp.Tests/ResetHeadFixture.cs
index 82fe2c53..870e46c3 100644
--- a/LibGit2Sharp.Tests/ResetHeadFixture.cs
+++ b/LibGit2Sharp.Tests/ResetHeadFixture.cs
@@ -18,7 +18,7 @@ namespace LibGit2Sharp.Tests
 
             using (var repo = new Repository(repoPath))
             {
-                Assert.Throws<LibGit2SharpException>(() => repo.Reset(ResetMode.Soft));
+                Assert.Throws<UnbornBranchException>(() => repo.Reset(ResetMode.Soft));
             }
         }
 
diff --git a/LibGit2Sharp.Tests/ResetIndexFixture.cs b/LibGit2Sharp.Tests/ResetIndexFixture.cs
index 0e774cd7..9cc7849a 100644
--- a/LibGit2Sharp.Tests/ResetIndexFixture.cs
+++ b/LibGit2Sharp.Tests/ResetIndexFixture.cs
@@ -25,7 +25,7 @@ namespace LibGit2Sharp.Tests
 
             using (var repo = new Repository(repoPath))
             {
-                Assert.Throws<LibGit2SharpException>(() => repo.Reset());
+                Assert.Throws<UnbornBranchException>(() => repo.Reset());
             }
         }
 
diff --git a/LibGit2Sharp.Tests/TagFixture.cs b/LibGit2Sharp.Tests/TagFixture.cs
index 97f5b24d..6426ccb1 100644
--- a/LibGit2Sharp.Tests/TagFixture.cs
+++ b/LibGit2Sharp.Tests/TagFixture.cs
@@ -234,7 +234,7 @@ namespace LibGit2Sharp.Tests
 
             using (var repo = new Repository(repoPath))
             {
-                Assert.Throws<LibGit2SharpException>(() => repo.ApplyTag("mynotag"));
+                Assert.Throws<UnbornBranchException>(() => repo.ApplyTag("mynotag"));
             }
         }
 
@@ -246,7 +246,8 @@ namespace LibGit2Sharp.Tests
 
             using (var repo = new Repository(repoPath))
             {
-                Assert.Throws<LibGit2SharpException>(() => repo.ApplyTag("mytaghead", "HEAD"));
+                Assert.Throws<UnbornBranchException>(() => repo.ApplyTag("mytaghead", "HEAD"));
+                Assert.Throws<UnbornBranchException>(() => repo.ApplyTag("mytaghead"));
             }
         }
 
@@ -288,6 +289,26 @@ namespace LibGit2Sharp.Tests
         }
 
         [Fact]
+        public void CanAddATagForImplicitHeadInDetachedState()
+        {
+            string path = CloneStandardTestRepo();
+            using (var repo = new Repository(path))
+            {
+                repo.Checkout(repo.Head.Tip);
+
+                Assert.True(repo.Info.IsHeadDetached);
+
+                Tag tag = repo.ApplyTag("mytag");
+                Assert.NotNull(tag);
+
+                Assert.Equal(repo.Head.Tip.Id, tag.Target.Id);
+
+                Tag retrievedTag = repo.Tags[tag.CanonicalName];
+                Assert.Equal(retrievedTag, tag);
+            }
+        }
+
+        [Fact]
         // Ported from cgit (https://github.com/git/git/blob/1c08bf50cfcf924094eca56c2486a90e2bf1e6e2/t/t7004-tag.sh#L87)
         public void CreatingADuplicateTagThrows()
         {