Commit `03620cf7bd`

03620cf7bd8bed1f3d3e8f9e47039f4762b8c4ff

parent: a37c74fc70

Verified · cmc ci/build: success ci/sonar: success ci/test: success ci/vuln: success

cmc <hello@cleberg.net> · 2026-09-06 21:41 UTC

ci: filter a rewritten branch against the merge base, not the old tip

A force-push makes old..new the difference between two histories. After
a rebase that is whatever the new base added, so a branch whose own
commits change code looks like a docs-only push, its jobs are skipped,
and it reads as green without having run.

Closes #176

Layout: unified · split

internal/control/build.go +14

		@@ -633,6 +633,20 @@ func queueJobs(
633	633	continue
634	634	}
635	635	diffOld := old
	636	// A force-push rewrote the branch, so the old tip is not an
	637	// ancestor of the new one and old..new is not "what this push
	638	// changed" — it is the difference between two histories. After a
	639	// rebase that is whatever the new base added, typically nothing
	640	// the branch itself touched, so every path filter concludes its
	641	// job is unnecessary and the branch reads as green without its
	642	// suite having run (#176). The merge base is the honest base:
	643	// the filter is deciding about the branch's relationship to its
	644	// target, which is what the merge base expresses.
	645	if ci.HasDiffBase(diffOld) && deriveMergeBase {
	646	if ok, err := gitutil.IsAncestor(dir, diffOld, sha); err != nil \|\| !ok {
	647	diffOld = ""
	648	}
	649	}
636	650	if !ci.HasDiffBase(diffOld) && deriveMergeBase {
637	651	if base, err := gitutil.MergeBase(dir, "refs/heads/"+repo.DefaultBranch, sha); err == nil && base != sha {
638	652	diffOld = base

internal/control/build_test.go +60

		@@ -489,3 +489,63 @@ func TestQueueMRBuildsStillFailsOpen(t *testing.T) {
489	489	t.Fatalf("expected the MR head to fail open and queue a build: %v %v", builds, err)
490	490	}
491	491	}
	492
	493	// A force-push that rewrote the branch must not filter against the old
	494	// tip. After a rebase, old..new is the difference between two histories
	495	// — whatever the new base added — so a branch whose own commits touch
	496	// code looks like a docs-only push and its jobs are skipped. It then
	497	// reads as green without having run (#176).
	498	func TestQueueBranchBuildsRebaseFiltersAgainstMergeBase(t *testing.T) {
	499	st, repo, uid := newQueueTestRepo(t)
	500	git := gitRunner(t)
	501	root := t.TempDir()
	502
	503	src := filepath.Join(root, "src")
	504	os.MkdirAll(filepath.Join(src, ".gitbay"), 0o755)
	505	os.MkdirAll(filepath.Join(src, "docs"), 0o755)
	506	os.MkdirAll(filepath.Join(src, "app"), 0o755)
	507	os.WriteFile(filepath.Join(src, ".gitbay", "ci.yml"), []byte(
	508	"jobs:\n unit:\n paths-ignore:\n - docs/**\n steps:\n - echo hi\n"), 0o644)
	509	os.WriteFile(filepath.Join(src, "app", "a.go"), []byte("package a\n"), 0o644)
	510	git(root, "init", "-q", "-b", "main", "src")
	511	git(src, "add", ".")
	512	git(src, "commit", "-q", "-m", "base")
	513
	514	// A branch that changes code — the kind of change the filter must
	515	// never skip.
	516	git(src, "checkout", "-q", "-b", "feat")
	517	os.WriteFile(filepath.Join(src, "app", "a.go"), []byte("package a\n\nvar X = 1\n"), 0o644)
	518	git(src, "add", ".")
	519	git(src, "commit", "-q", "-m", "code change")
	520	oldTip := strings.TrimSpace(git(src, "rev-parse", "HEAD"))
	521
	522	// main moves on with a docs-only commit, and the branch is rebased
	523	// onto it — exactly what a fast-forward-only repository forces.
	524	git(src, "checkout", "-q", "main")
	525	os.WriteFile(filepath.Join(src, "docs", "x.md"), []byte("# x\n"), 0o644)
	526	git(src, "add", ".")
	527	git(src, "commit", "-q", "-m", "docs only")
	528	git(src, "checkout", "-q", "feat")
	529	git(src, "rebase", "-q", "main")
	530	newTip := strings.TrimSpace(git(src, "rev-parse", "HEAD"))
	531
	532	// The trap: between the two tips lies only the docs commit.
	533	if diff := git(src, "diff", "--name-only", oldTip, newTip); !strings.Contains(diff, "docs/x.md") \|\|
	534	strings.Contains(diff, "app/a.go") {
	535	t.Fatalf("fixture does not reproduce the trap; old..new = %q", diff)
	536	}
	537
	538	dir := RepoDir(root, repo.OwnerName, repo.Name)
	539	os.MkdirAll(filepath.Dir(dir), 0o755)
	540	git(root, "clone", "-q", "--bare", src, dir)
	541
	542	QueueBranchBuilds(st, root, "https://x.test", repo, uid, "feat", oldTip, newTip, time.Now())
	543
	544	builds, err := st.ListBuilds(repo.ID, 10)
	545	if err != nil {
	546	t.Fatal(err)
	547	}
	548	if len(builds) == 0 {
	549	t.Fatal("a rebased branch whose commits change code queued no build")
	550	}
	551	}

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