linguist: Add test case causing crashtoon-linguist-crash-no-more

I've seen Gitaly crash in production [1]. This change adds a test case
emulating the crash so we can fix it.

The crash originally happened on [2].

[1]: https://gitlab.com/gitlab-com/gl-infra/production/-/issues/7864
[2]: https://gitlab.com/GodotBuilder/godot3

Issue: https://gitlab.com/gitlab-org/gitaly/-/issues/4523

1 files changed, 28 insertions, 0 deletions

diff --git a/internal/gitaly/linguist/linguist_test.go b/internal/gitaly/linguist/linguist_test.go
index 5d0ae925e..6ac60fe55 100644
--- a/internal/gitaly/linguist/linguist_test.go
+++ b/internal/gitaly/linguist/linguist_test.go
@@ -426,6 +426,34 @@ func testInstanceStats(t *testing.T, ctx context.Context) {
 			},
 		},
 		{
+			desc: "buggy behavior",
+			setup: func(t *testing.T) (*gitalypb.Repository, string, git.ObjectID) {
+				repoProto, repoPath := gittest.CreateRepository(ctx, t, cfg, gittest.CreateRepositoryConfig{
+					SkipCreationViaService: true,
+				})
+
+				amdTree := gittest.WriteTree(t, cfg, repoPath, []gittest.TreeEntry{
+					{Path: "ffx_a.h", Mode: "100644", Content: strings.Repeat("a", 349)},
+				})
+				thirdPartyTree := gittest.WriteTree(t, cfg, repoPath, []gittest.TreeEntry{
+					{Path: "README.md", Mode: "100644", Content: strings.Repeat("a", 234)},
+					{Path: "amd-fsr", Mode: "040000", OID: amdTree},
+				})
+
+				commitID := gittest.WriteCommit(t, cfg, repoPath, gittest.WithTreeEntries(
+					gittest.TreeEntry{Path: "thirdparty", Mode: "040000", OID: thirdPartyTree},
+					gittest.TreeEntry{
+						Path:    ".gitattributes",
+						Mode:    "100644",
+						Content: "*.h linguist-language=cpp\nthirdparty/* linguist-vendored",
+					},
+				))
+
+				return repoProto, repoPath, commitID
+			},
+			expectedStats: ByteCountPerLanguage{},
+		},
+		{
 			desc: "corrupted cache",
 			setup: func(t *testing.T) (*gitalypb.Repository, string, git.ObjectID) {
 				repoProto, repoPath := gittest.CreateRepository(ctx, t, cfg, gittest.CreateRepositoryConfig{