git: worktree_commit, Modify checking empty commit. Fixes #723

worktree_commit.go

@@ -38,8 +38,6 @@ func (w *Worktree) Commit(msg string, opts *CommitOptions) (plumbing.Hash, error
 		}
 	}
 
-	var treeHash plumbing.Hash
-
 	if opts.Amend {
 		head, err := w.r.Head()
 		if err != nil {
@@ -66,7 +64,7 @@ func (w *Worktree) Commit(msg string, opts *CommitOptions) (plumbing.Hash, error
 		s:  w.r.Storer,
 	}
 
-	treeHash, err = h.BuildTree(idx, opts)
+	treeHash, err := h.BuildTree(idx, opts)
 	if err != nil {
 		return plumbing.ZeroHash, err
 	}
@@ -175,7 +173,10 @@ type buildTreeHelper struct {
 // BuildTree builds the tree objects and push its to the storer, the hash
 // of the root tree is returned.
 func (h *buildTreeHelper) BuildTree(idx *index.Index, opts *CommitOptions) (plumbing.Hash, error) {
-	if len(idx.Entries) == 0 && (opts == nil || !opts.AllowEmptyCommits) {
+	allowEmpty := opts != nil && opts.AllowEmptyCommits
+
+	if len(opts.Parents) == 0 && len(idx.Entries) == 0 && !allowEmpty {
+		// Empty initial commit is filtered first
 		return plumbing.ZeroHash, ErrEmptyCommit
 	}
 
@@ -189,7 +190,21 @@ func (h *buildTreeHelper) BuildTree(idx *index.Index, opts *CommitOptions) (plum
 		}
 	}
 
-	return h.copyTreeToStorageRecursive(rootNode, h.trees[rootNode])
+	treeHash, err := h.copyTreeToStorageRecursive(rootNode, h.trees[rootNode])
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	parentHash := plumbing.ZeroHash
+	if len(opts.Parents) > 0 {
+		parentHash = opts.Parents[0]
+	}
+
+	if treeHash == parentHash && !allowEmpty {
+		return plumbing.ZeroHash, ErrEmptyCommit
+	}
+
+	return treeHash, nil
 }
 
 func (h *buildTreeHelper) commitIndexEntry(e *index.Entry) error {

worktree_commit_test.go

@@ -89,6 +89,33 @@ func (s *WorktreeSuite) TestNothingToCommit(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *WorktreeSuite) TestRemoveAndCommitToMakeEmptyRepo(c *C) {
+	fs := memfs.New()
+	r, err := Init(memory.NewStorage(), fs)
+	c.Assert(err, IsNil)
+
+	w, err := r.Worktree()
+	c.Assert(err, IsNil)
+
+	err = util.WriteFile(fs, "foo", []byte("foo"), 0644)
+	c.Assert(err, IsNil)
+
+	_, err = w.Add("foo")
+	c.Assert(err, IsNil)
+
+	_, err = w.Commit("Add in Repo\n", &CommitOptions{Author: defaultSignature()})
+	c.Assert(err, IsNil)
+
+	err = fs.Remove("foo")
+	c.Assert(err, IsNil)
+
+	_, err = w.Add("foo")
+	c.Assert(err, IsNil)
+
+	_, err = w.Commit("Remove foo\n", &CommitOptions{Author: defaultSignature()})
+	c.Assert(err, IsNil)
+}
+
 func (s *WorktreeSuite) TestCommitParent(c *C) {
 	expected := plumbing.NewHash("ef3ca05477530b37f48564be33ddd48063fc7a22")