misc/swig: move tests to cmd/cgo/internal

This moves the misc/swig test to cmd/cgo/internal.

This lets these tests access facilities in internal/testenv. It's also
now just a normal test that can run as part of the cmd tests.

For #37486.

Change-Id: Ibe5026219999d175aa0a310b9886bef3f6f9ed17
Reviewed-on: https://go-review.googlesource.com/c/go/+/492722
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

misc/swig/nocgo_test.go

@@ -1,7 +0,0 @@
-// Copyright 2023 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// This file is just to avoid build errors if there's no cgo.
-
-package swig

src/cmd/cgo/internal/swig/swig_test.go

@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build cgo
-
 package swig
 
 import (
-	"bytes"
+	"cmd/internal/quoted"
+	"internal/testenv"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -19,11 +18,13 @@ import (
 )
 
 func TestStdio(t *testing.T) {
+	testenv.MustHaveCGO(t)
 	mustHaveSwig(t)
 	run(t, "testdata/stdio", false)
 }
 
 func TestCall(t *testing.T) {
+	testenv.MustHaveCGO(t)
 	mustHaveSwig(t)
 	mustHaveCxx(t)
 	run(t, "testdata/callback", false, "Call")
@@ -31,6 +32,7 @@ func TestCall(t *testing.T) {
 }
 
 func TestCallback(t *testing.T) {
+	testenv.MustHaveCGO(t)
 	mustHaveSwig(t)
 	mustHaveCxx(t)
 	run(t, "testdata/callback", false, "Callback")
@@ -63,12 +65,14 @@ func mustHaveCxx(t *testing.T) {
 	if err != nil {
 		t.Fatalf("go env CXX failed: %s", err)
 	}
-	cxx = bytes.TrimSuffix(cxx, []byte("\n"))
-	// TODO(austin): "go env CXX" can return a quoted list. Use quoted.Split.
-	p, err := exec.LookPath(string(cxx))
-	if p == "" {
-		t.Skipf("test requires C++ compiler, but failed to find %s: %s", string(cxx), err)
+	args, err := quoted.Split(string(cxx))
+	if err != nil {
+		t.Skipf("could not parse 'go env CXX' output %q: %s", string(cxx), err)
 	}
+	if len(args) == 0 {
+		t.Skip("no C++ compiler")
+	}
+	testenv.MustHaveExecPath(t, string(args[0]))
 }
 
 var (

src/cmd/dist/test.go

@@ -870,9 +870,6 @@ func (t *tester) registerTests() {
 		if goos != "android" {
 			t.registerTest("cgo_testfortran", "", &goTest{dir: "cmd/cgo/internal/testfortran", timeout: 5 * time.Minute}, rtHostTest{})
 		}
-		if goos != "android" {
-			t.registerTest("swig", "", &goTest{dir: "../misc/swig"})
-		}
 	}
 	if t.cgoEnabled {
 		t.registerCgoTests()