feat(internal/gitrepo): add git log functionality (#2510)

Updates #2378

Author: JoeWang1127

internal/gitrepo/gitrepo.go

@@ -45,6 +45,7 @@ type Repository interface {
 	HeadHash() (string, error)
 	ChangedFilesInCommit(commitHash string) ([]string, error)
 	GetCommit(commitHash string) (*Commit, error)
+	GetLatestCommit(path string) (*Commit, error)
 	GetCommitsForPathsSinceTag(paths []string, tagName string) ([]*Commit, error)
 	GetCommitsForPathsSinceCommit(paths []string, sinceCommit string) ([]*Commit, error)
 	CreateBranchAndCheckout(name string) error
@@ -274,6 +275,29 @@ func (r *LocalRepository) GetCommit(commitHash string) (*Commit, error) {
 	}, nil
 }
 
+// GetLatestCommit returns the latest commit of the given path in the repository.
+func (r *LocalRepository) GetLatestCommit(path string) (*Commit, error) {
+	opt := &git.LogOptions{
+		Order:    git.LogOrderCommitterTime,
+		FileName: &path,
+	}
+	log, err := r.repo.Log(opt)
+	if err != nil {
+		return nil, err
+	}
+
+	commit, err := log.Next()
+	if err != nil {
+		return nil, err
+	}
+
+	return &Commit{
+		Hash:    commit.Hash,
+		Message: commit.Message,
+		When:    commit.Author.When,
+	}, nil
+}
+
 // GetCommitsForPathsSinceTag returns all commits since tagName that contains
 // files in paths.
 //

internal/gitrepo/gitrepo_test.go

@@ -15,6 +15,7 @@
 package gitrepo
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -1274,6 +1275,60 @@ func TestCleanUntracked(t *testing.T) {
 	}
 }
 
+func TestGetLatestCommit(t *testing.T) {
+	t.Parallel()
+	for _, test := range []struct {
+		name    string
+		path    string
+		setup   func(t *testing.T, repo *git.Repository, path string)
+		want    *Commit
+		wantErr error
+	}{
+		{
+			name: "get_latest_commit_of_a_path",
+			path: "a/path/example.txt",
+			setup: func(t *testing.T, repo *git.Repository, path string) {
+				createAndCommit(t, repo, path, []byte("1st content"), "first commit")
+				createAndCommit(t, repo, path, []byte("2nd content"), "second commit")
+				createAndCommit(t, repo, "another/path/example.txt", []byte("2nd content"), "second commit")
+			},
+			want: &Commit{
+				Message: "second commit",
+			},
+		},
+		{
+			name: "no_commit_of_a_path",
+			path: "a/path/example.txt",
+			setup: func(t *testing.T, repo *git.Repository, path string) {
+				// Do nothing.
+			},
+			wantErr: plumbing.ErrReferenceNotFound,
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+			repo, dir := initTestRepo(t)
+			test.setup(t, repo, test.path)
+			localRepo := &LocalRepository{Dir: dir, repo: repo}
+			got, err := localRepo.GetLatestCommit(test.path)
+			if test.wantErr != nil {
+				if !errors.Is(err, test.wantErr) {
+					t.Errorf("unexpected error type: got %v, want %v", err, test.wantErr)
+				}
+
+				return
+			}
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			if diff := cmp.Diff(test.want, got, cmpopts.IgnoreFields(Commit{}, "When", "Hash")); diff != "" {
+				t.Errorf("GetLatestCommit() mismatch in %s (-want +got):\n%s", test.name, diff)
+			}
+		})
+	}
+}
+
 // initTestRepo creates a new git repository in a temporary directory.
 func initTestRepo(t *testing.T) (*git.Repository, string) {
 	t.Helper()