os: improve TestExecutable

Instead of running all tests and relying on an init function, let's
embed the child code into the test case and only run one specific test.

Change-Id: Ib04e8a580556e7e30ff776c2041f0b809b440a26
Reviewed-on: https://go-review.googlesource.com/c/go/+/609838
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/os/executable_test.go b/src/os/executable_test.go
index be3c1dc72d979941db23627b64a4864f00e68bb8..1770843c7af8e71f901b24a7f6edf04c60c83406 100644 (file)
--- a/src/os/executable_test.go
+++ b/src/os/executable_test.go
@@ -13,11 +13,29 @@ import (
        "testing"
 )
 
-const executable_EnvVar = "OSTEST_OUTPUT_EXECPATH"
-
 func TestExecutable(t *testing.T) {
-       t.Parallel()
+       const helperEnvVar = "OSTEST_OUTPUT_EXECPATH"
+
+       if os.Getenv(helperEnvVar) != "" {
+               // First chdir to another path.
+               dir := "/"
+               if runtime.GOOS == "windows" {
+                       cwd, err := os.Getwd()
+                       if err != nil {
+                               panic(err)
+                       }
+                       dir = filepath.VolumeName(cwd)
+               }
+               os.Chdir(dir)
+               if ep, err := os.Executable(); err != nil {
+                       fmt.Fprint(os.Stderr, "ERROR: ", err)
+               } else {
+                       fmt.Fprint(os.Stderr, ep)
+               }
+               os.Exit(0)
+       }
 
+       t.Parallel()
        ep := testenv.Executable(t)
        // we want fn to be of the form "dir/prog"
        dir := filepath.Dir(filepath.Dir(ep))
@@ -26,7 +44,7 @@ func TestExecutable(t *testing.T) {
                t.Fatalf("filepath.Rel: %v", err)
        }
 
-       cmd := testenv.Command(t, fn, "-test.run=^$")
+       cmd := testenv.Command(t, fn, "-test.run=^"+t.Name()+"$")
        // make child start with a relative program path
        cmd.Dir = dir
        cmd.Path = fn
@@ -37,7 +55,7 @@ func TestExecutable(t *testing.T) {
                // get real path of the executable without influenced by argv[0].
                cmd.Args[0] = "-"
        }
-       cmd.Env = append(cmd.Environ(), fmt.Sprintf("%s=1", executable_EnvVar))
+       cmd.Env = append(cmd.Environ(), fmt.Sprintf("%s=1", helperEnvVar))
        out, err := cmd.CombinedOutput()
        if err != nil {
                t.Fatalf("exec(self) failed: %v", err)
@@ -63,27 +81,6 @@ func sameFile(fn1, fn2 string) bool {
        return os.SameFile(fi1, fi2)
 }
 
-func init() {
-       if e := os.Getenv(executable_EnvVar); e != "" {
-               // first chdir to another path
-               dir := "/"
-               if runtime.GOOS == "windows" {
-                       cwd, err := os.Getwd()
-                       if err != nil {
-                               panic(err)
-                       }
-                       dir = filepath.VolumeName(cwd)
-               }
-               os.Chdir(dir)
-               if ep, err := os.Executable(); err != nil {
-                       fmt.Fprint(os.Stderr, "ERROR: ", err)
-               } else {
-                       fmt.Fprint(os.Stderr, ep)
-               }
-               os.Exit(0)
-       }
-}
-
 func TestExecutableDeleted(t *testing.T) {
        testenv.MustHaveGoBuild(t)
        switch runtime.GOOS {