misc/cgo: skip cgotest.TestCrossPackageTests on iOS and set PWD

I hope that this will fix the tests on iOS, but 'gomote create' isn't
giving me an instance I can test with. (Please patch and test before
approving.)

Updates #15919
Updates #30228

Change-Id: I1b7cd30d5b127a1ad3243b329fa005d229f69a24
Reviewed-on: https://go-review.googlesource.com/c/163726
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Elias Naur <mail@eliasnaur.com>

misc/cgo/life/life_test.go

@@ -37,6 +37,7 @@ func testMain(m *testing.M) int {
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", modRoot)
 	if err := ioutil.WriteFile("go.mod", []byte("module cgolife\n"), 0666); err != nil {
 		log.Panic(err)
 	}

misc/cgo/stdio/stdio_test.go

@@ -37,6 +37,7 @@ func testMain(m *testing.M) int {
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", modRoot)
 	if err := ioutil.WriteFile("go.mod", []byte("module cgostdio\n"), 0666); err != nil {
 		log.Panic(err)
 	}

misc/cgo/test/pkg_test.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -26,6 +27,13 @@ import (
 // this shim and move the tests currently located in testdata back into the
 // parent directory.
 func TestCrossPackageTests(t *testing.T) {
+	if runtime.GOOS == "darwin" {
+		switch runtime.GOARCH {
+		case "arm", "arm64":
+			t.Skip("Can't exec cmd/go subprocess on iOS.")
+		}
+	}
+
 	GOPATH, err := ioutil.TempDir("", "cgotest")
 	if err != nil {
 		t.Fatal(err)

misc/cgo/testcarchive/carchive_test.go

@@ -60,6 +60,7 @@ func testMain(m *testing.M) int {
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", modRoot)
 	if err := ioutil.WriteFile("go.mod", []byte("module testcarchive\n"), 0666); err != nil {
 		log.Panic(err)
 	}

misc/cgo/testcshared/cshared_test.go

@@ -132,6 +132,7 @@ func testMain(m *testing.M) int {
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", modRoot)
 	if err := ioutil.WriteFile("go.mod", []byte("module testcshared\n"), 0666); err != nil {
 		log.Panic(err)
 	}

misc/cgo/testplugin/plugin_test.go

@@ -51,12 +51,14 @@ func TestMain(m *testing.M) {
 	if err := os.Chdir(altRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", altRoot)
 	goCmd(nil, "build", "-buildmode=plugin", "-o", filepath.Join(modRoot, "plugin-mismatch.so"), "./plugin-mismatch")
 
 	os.Setenv("GOPATH", GOPATH)
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
 	}
+	os.Setenv("PWD", modRoot)
 
 	os.Setenv("LD_LIBRARY_PATH", modRoot)
 

misc/cgo/testshared/shared_test.go

@@ -126,6 +126,7 @@ func testMain(m *testing.M) (int, error) {
 		fmt.Printf("+ cd %s\n", modRoot)
 	}
 	os.Chdir(modRoot)
+	os.Setenv("PWD", modRoot)
 	if err := ioutil.WriteFile("go.mod", []byte("module testshared\n"), 0666); err != nil {
 		return 0, err
 	}