Fix moreflag to make command line args win over env vars. (bazelbuild…

…#123)

* Fix moreflag to make command line args win over env vars.

* Fix moreflag to make command line args win over env vars.

go/pkg/moreflag/moreflag.go

@@ -16,8 +16,8 @@ import (
 // It also calls flag.Parse() to parse flags sent directly as arguments, unless flag.Parse
 // has been previously called.
 func Parse() {
-	ParseFromEnv()
 	if !flag.Parsed() {
+		ParseFromEnv()
 		flag.Parse()
 	}
 }

go/pkg/moreflag/moreflag_test.go

@@ -8,14 +8,21 @@ import (
 	"github.com/google/go-cmp/cmp"
 )
 
-func TestParse(t *testing.T) {
+func TestParseUnset(t *testing.T) {
+	cleanup := setCommandLine(t, []string{"cmd"})
+	defer cleanup()
 	f := flag.String("value", "", "Some value")
 
 	Parse()
 	if *f != "" {
 		t.Errorf("Flag has wrong value, want '', got %q", *f)
 	}
+}
 
+func TestParseSet(t *testing.T) {
+	cleanup := setCommandLine(t, []string{"cmd"})
+	defer cleanup()
+	f := flag.String("value", "", "Some value")
 	os.Setenv("FLAG_value", "test")
 	defer os.Setenv("FLAG_value", "")
 	Parse()
@@ -24,6 +31,26 @@ func TestParse(t *testing.T) {
 	}
 }
 
+func TestParseCommandLineWins(t *testing.T) {
+	cleanup := setCommandLine(t, []string{"cmd", "--value=cmd"})
+	defer cleanup()
+	f := flag.String("value", "", "Some value")
+	os.Setenv("FLAG_value", "test")
+	defer os.Setenv("FLAG_value", "")
+	Parse()
+	if *f != "cmd" {
+		t.Errorf("Flag has wrong value, want 'cmd', got %q", *f)
+	}
+}
+
+func setCommandLine(t *testing.T, args []string) func() {
+	t.Helper()
+	oldArgs := os.Args
+	os.Args = args
+	flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	return func() { os.Args = oldArgs }
+}
+
 func TestMapValueSet(t *testing.T) {
 	tests := []struct {
 		name    string