plumbing: blame, Complete rewrite. Fixes #603

Signed-off-by: Arieh Schneier <15041913+AriehSchneier@users.noreply.github.com>

2 files changed, 81 insertions, 0 deletions

diff --git a/plumbing/object/commit.go b/plumbing/object/commit.go
index d2f7184..8a0f35c 100644
--- a/plumbing/object/commit.go
+++ b/plumbing/object/commit.go
@@ -376,6 +376,17 @@ func (c *Commit) Verify(armoredKeyRing string) (*openpgp.Entity, error) {
 	return openpgp.CheckArmoredDetachedSignature(keyring, er, signature, nil)
 }
 
+// Less defines a compare function to determine which commit is 'earlier' by:
+// - First use Committer.When
+// - If Committer.When are equal then use Author.When
+// - If Author.When also equal then compare the string value of the hash
+func (c *Commit) Less(rhs *Commit) bool {
+	return c.Committer.When.Before(rhs.Committer.When) ||
+		(c.Committer.When.Equal(rhs.Committer.When) &&
+			(c.Author.When.Before(rhs.Author.When) ||
+				(c.Author.When.Equal(rhs.Author.When) && bytes.Compare(c.Hash[:], rhs.Hash[:]) < 0)))
+}
+
 func indent(t string) string {
 	var output []string
 	for _, line := range strings.Split(t, "\n") {
diff --git a/plumbing/object/commit_test.go b/plumbing/object/commit_test.go
index a939bc6..4b0f6b4 100644
--- a/plumbing/object/commit_test.go
+++ b/plumbing/object/commit_test.go
@@ -503,3 +503,73 @@ func (s *SuiteCommit) TestEncodeWithoutSignature(c *C) {
 		"\n"+
 		"Merge branch 'master' of github.com:tyba/git-fixture\n")
 }
+
+func (s *SuiteCommit) TestLess(c *C) {
+	when1 := time.Now()
+	when2 := when1.Add(time.Hour)
+
+	hash1 := plumbing.NewHash("1669dce138d9b841a518c64b10914d88f5e488ea")
+	hash2 := plumbing.NewHash("2669dce138d9b841a518c64b10914d88f5e488ea")
+
+	commitLessTests := []struct {
+		Committer1When, Committer2When time.Time
+		Author1When, Author2When       time.Time
+		Hash1, Hash2                   plumbing.Hash
+		Exp                            bool
+	}{
+		{when1, when1, when1, when1, hash1, hash2, true},
+		{when1, when1, when1, when1, hash2, hash1, false},
+		{when1, when1, when1, when2, hash1, hash2, true},
+		{when1, when1, when1, when2, hash2, hash1, true},
+		{when1, when1, when2, when1, hash1, hash2, false},
+		{when1, when1, when2, when1, hash2, hash1, false},
+		{when1, when1, when2, when2, hash1, hash2, true},
+		{when1, when1, when2, when2, hash2, hash1, false},
+		{when1, when2, when1, when1, hash1, hash2, true},
+		{when1, when2, when1, when1, hash2, hash1, true},
+		{when1, when2, when1, when2, hash1, hash2, true},
+		{when1, when2, when1, when2, hash2, hash1, true},
+		{when1, when2, when2, when1, hash1, hash2, true},
+		{when1, when2, when2, when1, hash2, hash1, true},
+		{when1, when2, when2, when2, hash1, hash2, true},
+		{when1, when2, when2, when2, hash2, hash1, true},
+		{when2, when1, when1, when1, hash1, hash2, false},
+		{when2, when1, when1, when1, hash2, hash1, false},
+		{when2, when1, when1, when2, hash1, hash2, false},
+		{when2, when1, when1, when2, hash2, hash1, false},
+		{when2, when1, when2, when1, hash1, hash2, false},
+		{when2, when1, when2, when1, hash2, hash1, false},
+		{when2, when1, when2, when2, hash1, hash2, false},
+		{when2, when1, when2, when2, hash2, hash1, false},
+		{when2, when2, when1, when1, hash1, hash2, true},
+		{when2, when2, when1, when1, hash2, hash1, false},
+		{when2, when2, when1, when2, hash1, hash2, true},
+		{when2, when2, when1, when2, hash2, hash1, true},
+		{when2, when2, when2, when1, hash1, hash2, false},
+		{when2, when2, when2, when1, hash2, hash1, false},
+		{when2, when2, when2, when2, hash1, hash2, true},
+		{when2, when2, when2, when2, hash2, hash1, false},
+	}
+
+	for _, t := range commitLessTests {
+		commit1 := &Commit{
+			Hash: t.Hash1,
+			Author: Signature{
+				When: t.Author1When,
+			},
+			Committer: Signature{
+				When: t.Committer1When,
+			},
+		}
+		commit2 := &Commit{
+			Hash: t.Hash2,
+			Author: Signature{
+				When: t.Author2When,
+			},
+			Committer: Signature{
+				When: t.Committer2When,
+			},
+		}
+		c.Assert(commit1.Less(commit2), Equals, t.Exp)
+	}
+}