ref: Refactor RefExists tests to generate data at runtime

Refactor RefExists tests to generate the test data at runtime, which
will enable us to start testing the RPC with the SHA256 object format.
While at it, convert the tests to be fully table-driven.

internal/gitaly/service/ref/refexists_test.go

-//go:build !gitaly_test_sha256
-
 package ref
 
 import (
 	"testing"
 
+	"gitlab.com/gitlab-org/gitaly/v16/internal/git"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/git/gittest"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/gitaly/storage"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/structerr"
 	"gitlab.com/gitlab-org/gitaly/v16/internal/testhelper"
 	"gitlab.com/gitlab-org/gitaly/v16/proto/go/gitalypb"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 )
 
 func TestRefExists(t *testing.T) {
 	t.Parallel()
 
 	ctx := testhelper.Context(t)
-	_, repo, _, client := setupRefService(t, ctx)
+	cfg, client := setupRefServiceWithoutRepo(t)
+
+	repo, repoPath := gittest.CreateRepository(t, ctx, cfg)
+	commitID := gittest.WriteCommit(t, cfg, repoPath)
+	for _, ref := range []git.ReferenceName{"refs/heads/master", "refs/tags/v1.0.0", "refs/heads/'test'", "refs/heads/ʕ•ᴥ•ʔ"} {
+		gittest.WriteRef(t, cfg, repoPath, ref, commitID)
+	}
 
 	for _, tc := range []struct {
 		desc             string
@@ -25,6 +29,21 @@ func TestRefExists(t *testing.T) {
 		expectedResponse *gitalypb.RefExistsResponse
 		expectedErr      error
 	}{
+		{
+			desc: "repository not provided",
+			request: &gitalypb.RefExistsRequest{
+				Repository: nil,
+			},
+			expectedErr: structerr.NewInvalidArgument("%w", storage.ErrRepositoryNotSet),
+		},
+		{
+			desc: "invalid ref name",
+			request: &gitalypb.RefExistsRequest{
+				Repository: repo,
+				Ref:        []byte("in valid"),
+			},
+			expectedErr: structerr.NewInvalidArgument("invalid refname"),
+		},
 		{
 			desc: "master",
 			request: &gitalypb.RefExistsRequest{
@@ -156,30 +175,3 @@ func TestRefExists(t *testing.T) {
 		})
 	}
 }
-
-func TestRefExists_validate(t *testing.T) {
-	t.Parallel()
-	ctx := testhelper.Context(t)
-	_, repo, _, client := setupRefService(t, ctx)
-	for _, tc := range []struct {
-		desc        string
-		req         *gitalypb.RefExistsRequest
-		expectedErr error
-	}{
-		{
-			desc:        "repository not provided",
-			req:         &gitalypb.RefExistsRequest{Repository: nil},
-			expectedErr: structerr.NewInvalidArgument("%w", storage.ErrRepositoryNotSet),
-		},
-		{
-			desc:        "invalid ref name",
-			req:         &gitalypb.RefExistsRequest{Repository: repo, Ref: []byte("in valid")},
-			expectedErr: status.Error(codes.InvalidArgument, "invalid refname"),
-		},
-	} {
-		t.Run(tc.desc, func(t *testing.T) {
-			_, err := client.RefExists(ctx, tc.req)
-			testhelper.RequireGrpcError(t, tc.expectedErr, err)
-		})
-	}
-}