test(githttp): write the fake backend once to avoid ETXTBSY under parallel tests

Writing an executable while parallel tests fork lets a child inherit the
write descriptor, and exec of the script then fails with "text file busy"
(golang/go#22315). The fake git-http-backend is written once in TestMain, and
the hook script test that writes executables runs serially.

commit: 650dc0ac5f1156f67297bfa794dcf5a7f61a1c6d
author: brice · 10d ago · 2026-10-12 06:55 UTC
parent: 588fe2c
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +28 -4

M internal/adapters/githttp/handler_test.go +25 -3


@@ -31,12 +31,34 @@ import (
31	31		// environment and the body it received. Like Git, it reads the whole request
32	32		// before it answers (net/http cannot read a request body once the response
33	33		// has started).
	34	+	//
	35	+	// The script is written once, in TestMain, before any test runs: writing an
	36	+	// executable while parallel tests fork lets a child inherit the open write
	37	+	// descriptor, and exec then fails with ETXTBSY (golang/go#22315).
34	38		func cgiScript(t *testing.T) string {
35	39		t.Helper()
36		-	p := filepath.Join(t.TempDir(), "backend")
	40	+	require.NotEmpty(t, backendScript, "TestMain writes the backend script")
	41	+	return backendScript
	42	+	}
	43	+
	44	+	var backendScript string
	45	+
	46	+	func TestMain(m *testing.M) {
	47	+	os.Exit(runWithBackendScript(m))
	48	+	}
	49	+
	50	+	func runWithBackendScript(m *testing.M) int {
	51	+	dir, err := os.MkdirTemp("", "githttp-backend")
	52	+	if err != nil {
	53	+	panic(err)
	54	+	}
	55	+	defer func() { _ = os.RemoveAll(dir) }()
	56	+	backendScript = filepath.Join(dir, "backend")
37	57		body := "#!/bin/sh\nin=$(mktemp)\ncat > \"$in\"\nprintf 'Content-Type: text/plain\\r\\n\\r\\n'\nenv \| sort\nprintf '\\n--body--\\n'\ncat \"$in\"\nrm -f \"$in\"\n"
38		-	require.NoError(t, os.WriteFile(p, []byte(body), 0o755))
39		-	return p
	58	+	if err := os.WriteFile(backendScript, []byte(body), 0o755); err != nil {
	59	+	panic(err)
	60	+	}
	61	+	return m.Run()
40	62		}
41	63
42	64		type rig struct {


@@ -31,12 +31,34 @@ import (
31		// environment and the body it received. Like Git, it reads the whole request	31		// environment and the body it received. Like Git, it reads the whole request
32		// before it answers (net/http cannot read a request body once the response	32		// before it answers (net/http cannot read a request body once the response
33		// has started).	33		// has started).
			34	+	//
			35	+	// The script is written once, in TestMain, before any test runs: writing an
			36	+	// executable while parallel tests fork lets a child inherit the open write
			37	+	// descriptor, and exec then fails with ETXTBSY (golang/go#22315).
34		func cgiScript(t *testing.T) string {	38		func cgiScript(t *testing.T) string {
35		t.Helper()	39		t.Helper()
36	-	p := filepath.Join(t.TempDir(), "backend")	40	+	require.NotEmpty(t, backendScript, "TestMain writes the backend script")
			41	+	return backendScript
			42	+	}
			43	+
			44	+	var backendScript string
			45	+
			46	+	func TestMain(m *testing.M) {
			47	+	os.Exit(runWithBackendScript(m))
			48	+	}
			49	+
			50	+	func runWithBackendScript(m *testing.M) int {
			51	+	dir, err := os.MkdirTemp("", "githttp-backend")
			52	+	if err != nil {
			53	+	panic(err)
			54	+	}
			55	+	defer func() { _ = os.RemoveAll(dir) }()
			56	+	backendScript = filepath.Join(dir, "backend")
37		body := "#!/bin/sh\nin=$(mktemp)\ncat > \"$in\"\nprintf 'Content-Type: text/plain\\r\\n\\r\\n'\nenv \| sort\nprintf '\\n--body--\\n'\ncat \"$in\"\nrm -f \"$in\"\n"	57		body := "#!/bin/sh\nin=$(mktemp)\ncat > \"$in\"\nprintf 'Content-Type: text/plain\\r\\n\\r\\n'\nenv \| sort\nprintf '\\n--body--\\n'\ncat \"$in\"\nrm -f \"$in\"\n"
38	-	require.NoError(t, os.WriteFile(p, []byte(body), 0o755))	58	+	if err := os.WriteFile(backendScript, []byte(body), 0o755); err != nil {
39	-	return p	59	+	panic(err)
			60	+	}
			61	+	return m.Run()
40		}	62		}
41			63
42		type rig struct {	64		type rig struct {

M internal/adapters/githttp/hooks_test.go +3 -1


@@ -390,8 +390,10 @@ func TestWriteHookScripts(t *testing.T) {
390	390		}
391	391
392	392		// The shell really passes the awkward path and the arguments through.
	393	+	//
	394	+	// Not parallel: it writes executables, and a test that forks meanwhile would
	395	+	// inherit the write descriptor and make exec fail with ETXTBSY.
393	396		func TestHookScriptExecsTheBinaryWithQuotedPath(t *testing.T) {
394		-	t.Parallel()
395	397		base := filepath.Join(t.TempDir(), "it's a \"dir\" $X `y` ; z")
396	398		require.NoError(t, os.MkdirAll(base, 0o755))
397	399		exe := filepath.Join(base, "fake ermite")

 }
 // The shell really passes the awkward path and the arguments through.
+//
+// Not parallel: it writes executables, and a test that forks meanwhile would
+// inherit the write descriptor and make exec fail with ETXTBSY.
 func TestHookScriptExecsTheBinaryWithQuotedPath(t *testing.T) {
-	t.Parallel()
 	base := filepath.Join(t.TempDir(), "it's a \"dir\" $X `y` ; z")
 	require.NoError(t, os.MkdirAll(base, 0o755))
 	exe := filepath.Join(base, "fake ermite")