ref: Refactor test that writes thousands of references

One of the tests for the `FindAllBranchNames()` RPC exercises what
happens when we return thousands of references. To do so it creates a
git-update-ref(1) instance and queues up all updates to it. While this
is as efficient as it gets while using Git, it still is comparatively
expensive to do it this way as it requires locking and whatnot.

Refactor the test to just manually write out a `packed-refs` file.

1 files changed, 20 insertions, 23 deletions

diff --git a/internal/gitaly/service/ref/refs_test.go b/internal/gitaly/service/ref/refs_test.go
index f836da63f..5bd97483f 100644
--- a/internal/gitaly/service/ref/refs_test.go
+++ b/internal/gitaly/service/ref/refs_test.go
@@ -7,6 +7,8 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -14,7 +16,6 @@ import (
 	"gitlab.com/gitlab-org/gitaly/v15/internal/git"
 	"gitlab.com/gitlab-org/gitaly/v15/internal/git/gittest"
 	"gitlab.com/gitlab-org/gitaly/v15/internal/git/localrepo"
-	"gitlab.com/gitlab-org/gitaly/v15/internal/git/updateref"
 	"gitlab.com/gitlab-org/gitaly/v15/internal/helper"
 	"gitlab.com/gitlab-org/gitaly/v15/internal/testhelper"
 	"gitlab.com/gitlab-org/gitaly/v15/proto/go/gitalypb"
@@ -61,12 +62,10 @@ func TestSuccessfulFindAllBranchNames(t *testing.T) {
 //nolint:staticcheck
 func TestFindAllBranchNamesVeryLargeResponse(t *testing.T) {
 	ctx := testhelper.Context(t)
-	cfg, repoProto, _, client := setupRefService(t, ctx)
+	cfg, client := setupRefServiceWithoutRepo(t)
 
-	repo := localrepo.NewTestRepo(t, cfg, repoProto)
-	updater, err := updateref.New(ctx, repo)
-	require.NoError(t, err)
-	defer testhelper.MustClose(t, updater)
+	repoProto, repoPath := gittest.CreateRepository(t, ctx, cfg)
+	commitID := gittest.WriteCommit(t, cfg, repoPath)
 
 	// We want to create enough refs to overflow the default bufio.Scanner
 	// buffer. Such an overflow will cause scanner.Bytes() to become invalid
@@ -76,25 +75,26 @@ func TestFindAllBranchNamesVeryLargeResponse(t *testing.T) {
 	refSizeLowerBound := 100
 	numRefs := 2 * bufio.MaxScanTokenSize / refSizeLowerBound
 
-	require.NoError(t, updater.Start())
+	// Instead of using git-update-ref(1) to create the thousands of references we just write
+	// our own packed-refs file, which is significantly faster.
+	packedRefs, err := os.Create(filepath.Join(repoPath, "packed-refs"))
+	require.NoError(t, err)
 
-	var testRefs []string
+	var expectedRefs [][]byte
 	for i := 0; i < numRefs; i++ {
 		refName := fmt.Sprintf("refs/heads/test-%0100d", i)
-		require.True(t, len(refName) > refSizeLowerBound, "ref %q must be larger than %d", refName, refSizeLowerBound)
-
-		require.NoError(t, updater.Create(git.ReferenceName(refName), "HEAD"))
-		testRefs = append(testRefs, refName)
+		_, err := packedRefs.WriteString(fmt.Sprintf("%s %s\n", commitID, refName))
+		require.NoError(t, err)
+		expectedRefs = append(expectedRefs, []byte(refName))
 	}
+	testhelper.MustClose(t, packedRefs)
 
-	require.NoError(t, updater.Commit())
-
-	rpcRequest := &gitalypb.FindAllBranchNamesRequest{Repository: repoProto}
-
-	c, err := client.FindAllBranchNames(ctx, rpcRequest)
+	c, err := client.FindAllBranchNames(ctx, &gitalypb.FindAllBranchNamesRequest{
+		Repository: repoProto,
+	})
 	require.NoError(t, err)
 
-	var names [][]byte
+	var actualRefs [][]byte
 	for {
 		r, err := c.Recv()
 		if err == io.EOF {
@@ -102,12 +102,9 @@ func TestFindAllBranchNamesVeryLargeResponse(t *testing.T) {
 		}
 		require.NoError(t, err)
 
-		names = append(names, r.GetNames()...)
-	}
-
-	for _, branch := range testRefs {
-		require.Contains(t, names, []byte(branch), "branch missing from response: %q", branch)
+		actualRefs = append(actualRefs, r.GetNames()...)
 	}
+	require.Equal(t, expectedRefs, actualRefs)
 }
 
 //nolint:staticcheck