Urgh I made some wrong amends and I'm too tired to separate the commits out this time

ancestor: Split out of reachability
mergebase: Add merge base routines
internal/commitquery: Add commit query context engine thingy
internal/peel: Shared tag peeling
errors: Shared object query errors
internal/testgit: Add rooted repo helpers; remove raw path access
objectstore/memory: Add in-memory object store
objectid: Add Compare helper

1 files changed, 87 insertions, 0 deletions

diff --git a/internal/testgit/repo_open_root.go b/internal/testgit/repo_open_root.go
new file mode 100644
index 00000000..4530c604
--- /dev/null
+++ b/internal/testgit/repo_open_root.go
@@ -0,0 +1,87 @@
+package testgit
+
+import (
+	"errors"
+	"os"
+	"testing"
+)
+
+// OpenRoot opens the repository root directory and registers cleanup on the
+// caller.
+func (testRepo *TestRepo) OpenRoot(tb testing.TB) *os.Root {
+	tb.Helper()
+
+	root, err := os.OpenRoot(testRepo.dir)
+	if err != nil {
+		tb.Fatalf("os.OpenRoot: %v", err)
+	}
+
+	tb.Cleanup(func() {
+		_ = root.Close()
+	})
+
+	return root
+}
+
+// OpenGitRoot opens the repository gitdir and registers cleanup on the caller.
+//
+// For bare repositories, this is the repository root itself. For non-bare
+// repositories, this is the .git directory under the worktree root.
+func (testRepo *TestRepo) OpenGitRoot(tb testing.TB) *os.Root {
+	tb.Helper()
+
+	repoRoot := testRepo.OpenRoot(tb)
+
+	gitRoot, err := repoRoot.OpenRoot(".git")
+	if err == nil {
+		tb.Cleanup(func() {
+			_ = gitRoot.Close()
+		})
+
+		return gitRoot
+	}
+
+	if !errors.Is(err, os.ErrNotExist) {
+		tb.Fatalf("OpenRoot(.git): %v", err)
+	}
+
+	return repoRoot
+}
+
+// OpenObjectsRoot opens the objects directory and registers cleanup on the
+// caller.
+func (testRepo *TestRepo) OpenObjectsRoot(tb testing.TB) *os.Root {
+	tb.Helper()
+
+	gitRoot := testRepo.OpenGitRoot(tb)
+
+	objectsRoot, err := gitRoot.OpenRoot("objects")
+	if err != nil {
+		tb.Fatalf("OpenRoot(objects): %v", err)
+	}
+
+	tb.Cleanup(func() {
+		_ = objectsRoot.Close()
+	})
+
+	return objectsRoot
+}
+
+// OpenPackRoot opens the objects/pack directory and registers cleanup on the
+// caller.
+func (testRepo *TestRepo) OpenPackRoot(tb testing.TB) *os.Root {
+	tb.Helper()
+
+	objectsRoot := testRepo.OpenObjectsRoot(tb)
+
+	packRoot, err := objectsRoot.OpenRoot("pack")
+	if err != nil {
+		tb.Fatalf("OpenRoot(pack): %v", err)
+	}
+
+	tb.Cleanup(func() {
+		_ = packRoot.Close()
+	})
+
+	return packRoot
+}