internal/ci: copy how internal/vcs sets a clean env for git tests

Otherwise any users who have a git config that signs commits
automatically with a password prompt, like Paul,
would run into trouble as the tests would attempt such a prompt.

Expose the test helper in vcs to reuse it.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Iafb14a06a12868231be6f2ffb39d50387c4c8f52
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1198298
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Paul Jolly <paul@myitcv.io>

internal/ci/checks/commit_test.go

@@ -21,6 +21,8 @@ import (
 
 	"github.com/go-quicktest/qt"
 	"golang.org/x/tools/txtar"
+
+	"cuelang.org/go/internal/vcs"
 )
 
 func TestCommits(t *testing.T) {
@@ -36,6 +38,7 @@ func TestCommits(t *testing.T) {
 		t.Logf("commit:\n%s", commit)
 
 		dir := t.TempDir()
+		vcs.InitTestEnv(t)
 		mustRunCmd(t, dir, "git", "init")
 		mustRunCmd(t, dir, "git",
 			"-c", "user.email=cueckoo@gmail.com",

internal/vcs/vcs.go

@@ -23,6 +23,9 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
 	"time"
 )
 
@@ -133,3 +136,38 @@ type vcsNotFoundError struct {
 func (e *vcsNotFoundError) Error() string {
 	return fmt.Sprintf("%s VCS not found in any parent of %q", e.kind, e.dir)
 }
+
+func homeEnvName() string {
+	switch runtime.GOOS {
+	case "windows":
+		return "USERPROFILE"
+	case "plan9":
+		return "home"
+	default:
+		return "HOME"
+	}
+}
+
+// InitTestEnv sets up the environment so that any executed VCS command
+// won't be affected by the outer level environment.
+//
+// Note that this function is exposed so we can reuse it from other test packages
+// which also need to use Go tests with VCS systems.
+// Exposing a test helper is fine for now, given this is an internal package.
+func InitTestEnv(t testing.TB) {
+	t.Helper()
+	path := os.Getenv("PATH")
+	systemRoot := os.Getenv("SYSTEMROOT")
+	// First unset all environment variables to make a pristine environment.
+	for _, kv := range os.Environ() {
+		key, _, _ := strings.Cut(kv, "=")
+		t.Setenv(key, "")
+		os.Unsetenv(key)
+	}
+	os.Setenv("PATH", path)
+	os.Setenv(homeEnvName(), "/no-home")
+	// Must preserve SYSTEMROOT on Windows: https://github.com/golang/go/issues/25513 et al
+	if runtime.GOOS == "windows" {
+		os.Setenv("SYSTEMROOT", systemRoot)
+	}
+}

internal/vcs/vcs_test.go

@@ -19,8 +19,6 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"runtime"
-	"strings"
 	"testing"
 	"time"
 
@@ -53,7 +51,7 @@ func TestGit(t *testing.T) {
 	_, err = New("git", subdir)
 	qt.Assert(t, qt.ErrorMatches(err, `git VCS not found in any parent of ".+"`))
 
-	initTestEnv(t)
+	InitTestEnv(t)
 	mustRunCmd(t, dir, "git", "init")
 	v, err := New("git", subdir)
 	qt.Assert(t, qt.IsNil(err))
@@ -187,26 +185,6 @@ func TestGit(t *testing.T) {
 	qt.Assert(t, qt.IsTrue(statusmissing.Uncommitted))
 }
 
-// initTestEnv sets up the environment so that
-// any executed VCS command won't be affected
-// by the outer level environment.
-func initTestEnv(t *testing.T) {
-	path := os.Getenv("PATH")
-	systemRoot := os.Getenv("SYSTEMROOT")
-	// First unset all environment variables to make a pristine environment.
-	for _, kv := range os.Environ() {
-		key, _, _ := strings.Cut(kv, "=")
-		t.Setenv(key, "")
-		os.Unsetenv(key)
-	}
-	os.Setenv("PATH", path)
-	os.Setenv(homeEnvName(), "/no-home")
-	// Must preserve SYSTEMROOT on Windows: https://github.com/golang/go/issues/25513 et al
-	if runtime.GOOS == "windows" {
-		os.Setenv("SYSTEMROOT", systemRoot)
-	}
-}
-
 func mustRunCmd(t *testing.T, dir string, exe string, args ...string) {
 	c := exec.Command(exe, args...)
 	c.Dir = dir
@@ -219,14 +197,3 @@ func skipIfNoExecutable(t *testing.T, exeName string) {
 		t.Skipf("cannot find %q executable: %v", exeName, err)
 	}
 }
-
-func homeEnvName() string {
-	switch runtime.GOOS {
-	case "windows":
-		return "USERPROFILE"
-	case "plan9":
-		return "home"
-	default:
-		return "HOME"
-	}
-}