all: use testenv.Executable instead of os.Executable and os.Args[0]

In test files, using testenv.Executable is more reliable than
os.Executable or os.Args[0].

Change-Id: I88e577efeabc20d02ada27bf706ae4523129128e
Reviewed-on: https://go-review.googlesource.com/c/go/+/651955
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

3 files changed, 5 insertions, 6 deletions

diff --git a/src/cmd/cgo/internal/test/issue18146.go b/src/cmd/cgo/internal/test/issue18146.go
index 112b7ee2e7..04e5b5ffb8 100644
--- a/src/cmd/cgo/internal/test/issue18146.go
+++ b/src/cmd/cgo/internal/test/issue18146.go
@@ -11,6 +11,7 @@ package cgotest
 import (
 	"bytes"
 	"crypto/md5"
+	"internal/testenv"
 	"os"
 	"os/exec"
 	"runtime"
@@ -73,7 +74,7 @@ func test18146(t *testing.T) {
 		}
 		runtime.GOMAXPROCS(threads)
 		argv := append(os.Args, "-test.run=^$")
-		if err := syscall.Exec(os.Args[0], argv, os.Environ()); err != nil {
+		if err := syscall.Exec(testenv.Executable(t), argv, os.Environ()); err != nil {
 			t.Fatal(err)
 		}
 	}
@@ -87,7 +88,7 @@ func test18146(t *testing.T) {
 
 	args := append(append([]string(nil), os.Args[1:]...), "-test.run=^Test18146$")
 	for n := attempts; n > 0; n-- {
-		cmd := exec.Command(os.Args[0], args...)
+		cmd := exec.Command(testenv.Executable(t), args...)
 		cmd.Env = append(os.Environ(), "test18146=exec")
 		buf := bytes.NewBuffer(nil)
 		cmd.Stdout = buf
diff --git a/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go b/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
index 035840db7e..c1423e6087 100644
--- a/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
+++ b/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
@@ -198,7 +198,7 @@ func TestLockNotDroppedByExecCommand(t *testing.T) {
 	// Some kinds of file locks are dropped when a duplicated or forked file
 	// descriptor is unlocked. Double-check that the approach used by os/exec does
 	// not accidentally drop locks.
-	cmd := testenv.Command(t, os.Args[0], "-test.run=^$")
+	cmd := testenv.Command(t, testenv.Executable(t), "-test.run=^$")
 	if err := cmd.Run(); err != nil {
 		t.Fatalf("exec failed: %v", err)
 	}
diff --git a/src/cmd/go/internal/lockedfile/lockedfile_test.go b/src/cmd/go/internal/lockedfile/lockedfile_test.go
index 8cea197abc..514d0a316c 100644
--- a/src/cmd/go/internal/lockedfile/lockedfile_test.go
+++ b/src/cmd/go/internal/lockedfile/lockedfile_test.go
@@ -180,8 +180,6 @@ func TestSpuriousEDEADLK(t *testing.T) {
 	// 	P.2 unblocks and locks file B.
 	// 	P.2 unlocks file B.
 
-	testenv.MustHaveExec(t)
-
 	dirVar := t.Name() + "DIR"
 
 	if dir := os.Getenv(dirVar); dir != "" {
@@ -216,7 +214,7 @@ func TestSpuriousEDEADLK(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	cmd := testenv.Command(t, os.Args[0], "-test.run=^"+t.Name()+"$")
+	cmd := testenv.Command(t, testenv.Executable(t), "-test.run=^"+t.Name()+"$")
 	cmd.Env = append(os.Environ(), fmt.Sprintf("%s=%s", dirVar, dir))
 
 	qDone := make(chan struct{})