pkg/vcs: detect old git binary that can't do bisection

2 files changed, 12 insertions, 0 deletions

diff --git a/pkg/bisect/bisect_test.go b/pkg/bisect/bisect_test.go
index 7a1d02a90..ff4602278 100644
--- a/pkg/bisect/bisect_test.go
+++ b/pkg/bisect/bisect_test.go
@@ -85,6 +85,9 @@ func TestBisectCause(t *testing.T) {
 			}
 		}
 	}
+	if !originRepo.SupportsBisection() {
+		t.Skip("bisection is unsupported by git (probably too old version)")
+	}
 	repo := vcs.CloneTestRepo(t, baseDir, "repo", originRepo)
 	r, err := vcs.NewRepo("test", "64", repo.Dir)
 	if err != nil {
diff --git a/pkg/vcs/test_util.go b/pkg/vcs/test_util.go
index 55bd7bccd..148360a08 100644
--- a/pkg/vcs/test_util.go
+++ b/pkg/vcs/test_util.go
@@ -3,6 +3,7 @@ package vcs
 import (
 	"fmt"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -82,6 +83,14 @@ func (repo *TestRepo) SetTag(tag string) {
 	repo.git("tag", tag)
 }
 
+func (repo *TestRepo) SupportsBisection() bool {
+	// Detect too old git binary. --no-contains appeared in git 2.13.
+	_, err := repo.repo.previousReleaseTags("HEAD", true)
+	return err == nil ||
+		!strings.Contains(err.Error(), "usage: git tag") &&
+			!strings.Contains(err.Error(), "error: unknown option")
+}
+
 func CreateTestRepo(t *testing.T, baseDir, name string) *TestRepo {
 	repo := MakeTestRepo(t, filepath.Join(baseDir, name))
 	repo.git("checkout", "-b", "master")