MergeFixture: Added in recommended asserts

MergeResult: Fixed up bad reference + added FastForwardOid prop
Repository: Wrapped MergeHead and MergeResult handles in usings.

Author: angusbjones

LibGit2Sharp.Tests/MergeFixture.cs

@@ -89,16 +89,25 @@ public void CanMergeRepos()
             {
                 var firstBranch = repo.CreateBranch("FirstBranch");
                 firstBranch.Checkout();
-                AddFileCommitToRepo(repo, "first+second branch file");
+                var originalTreeCount = firstBranch.Tip.Tree.Count;
 
+                //Commit with ONE new file to both first & second branch (SecondBranch is created on this commit).
+                AddFileCommitToRepo(repo, "first+second branch file");  
+                
                 var secondBranch = repo.CreateBranch("SecondBranch");
-                AddFileCommitToRepo(repo, "first branch file");
+                //Commit with ONE new file to first branch (FirstBranch moves forward as it is checked out, SecondBranch stays back one).
+                var firstBranchCommit = AddFileCommitToRepo(repo, "first branch file"); 
+
                 secondBranch.Checkout();
-                AddFileCommitToRepo(repo, "second branch file");
+                //Commit with ONE new file to second branch (FirstBranch and SecondBranch now point to separate commits that both have the same parent commit).
+                var secondBranchCommit = AddFileCommitToRepo(repo, "second branch file");
+
+                MergeResult mergeResult = repo.Merge(repo.Branches["FirstBranch"].Tip);
 
-                repo.Merge(repo.Branches["FirstBranch"].Tip);
+                var mergeCommit = repo.Commit("Merge First+Second");
 
-                repo.Commit("Merge First+Second");
+                Assert.Equal(mergeCommit.Tree.Count, originalTreeCount + 3);    //Expecting original tree count plussed by the 3 added files.
+                Assert.Equal(mergeCommit.Parents.Count(), 2);   //Merge commit should have 2 parents
             }
         }
 

LibGit2Sharp/MergeResult.cs

@@ -10,7 +10,10 @@ public MergeResult(){}
         internal MergeResult(GitMergeResultHandle handle)
         {
             _isUpToDate = Proxy.git_merge_result_is_uptodate(handle);
-            _isUpToDate = Proxy.git_merge_result_is_fastforward(handle);
+            _isFastForward = Proxy.git_merge_result_is_fastforward(handle);
+
+            if (_isFastForward)
+                _oid = Proxy.git_merge_result_fastforward_oid(handle);
         }
 
         private bool _isUpToDate;
@@ -24,5 +27,11 @@ public virtual bool IsFastForward
         {
             get { return _isFastForward; }
         }
+
+        private readonly GitOid _oid;
+        internal GitOid FastForwardOid
+        {
+            get { return _oid; }
+        }
     }
 }

LibGit2Sharp/Repository.cs

@@ -1037,15 +1037,19 @@ public IEnumerable<MergeHead> MergeHeads
         /// </summary>
         public MergeResult Merge(Commit commit)
         {
-            var mergeHeadHandle = Proxy.git_merge_head_from_oid(Handle, commit.Id.Oid);
-
-            GitMergeOpts opts = new GitMergeOpts()
+            using (GitMergeHeadHandle mergeHeadHandle = Proxy.git_merge_head_from_oid(Handle, commit.Id.Oid))
             {
-                Version = 1,
-                MergeTreeOpts = { Version = 1 },
-                CheckoutOpts = { version = 1 }
-            };
-            return new MergeResult(Proxy.git_merge(Handle, new GitMergeHeadHandle[] { mergeHeadHandle }, opts));
+                GitMergeOpts opts = new GitMergeOpts()
+                {
+                    Version = 1,
+                    MergeTreeOpts = { Version = 1 },
+                    CheckoutOpts = { version = 1 }
+                };
+                using (GitMergeResultHandle mergeResultHandle = Proxy.git_merge(Handle, new GitMergeHeadHandle[] { mergeHeadHandle }, opts))
+                { 
+                    return new MergeResult(mergeResultHandle);
+                }
+            }
         }
 
         internal StringComparer PathComparer