go/packages: only run TestCgoNoSyntax when cgo is available

Fixes golang/go#36799

Change-Id: I3f2013891465bef1ef9a15097b3d4614b9856035
Reviewed-on: https://go-review.googlesource.com/c/tools/+/216538
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

go/packages/packages_test.go

@@ -2535,74 +2535,6 @@ func testForTestField(t *testing.T, exporter packagestest.Exporter) {
 	}
 }
 
-func TestCgoNoSyntax(t *testing.T) {
-	packagestest.TestAll(t, testCgoNoSyntax)
-}
-
-// Stolen from internal/testenv package in core.
-// hasGoBuild reports whether the current system can build programs with ``go build''
-// and then run them with os.StartProcess or exec.Command.
-func hasGoBuild() bool {
-	if os.Getenv("GO_GCFLAGS") != "" {
-		// It's too much work to require every caller of the go command
-		// to pass along "-gcflags="+os.Getenv("GO_GCFLAGS").
-		// For now, if $GO_GCFLAGS is set, report that we simply can't
-		// run go build.
-		return false
-	}
-	switch runtime.GOOS {
-	case "android", "js":
-		return false
-	case "darwin":
-		if strings.HasPrefix(runtime.GOARCH, "arm") {
-			return false
-		}
-	}
-	return true
-}
-
-func testCgoNoSyntax(t *testing.T, exporter packagestest.Exporter) {
-	// The android builders have a complex setup which causes this test to fail. See discussion on
-	// golang.org/cl/214943 for more details.
-	if !hasGoBuild() {
-		t.Skip("this test can't run on platforms without go build. See discussion on golang.org/cl/214943 for more details.")
-	}
-
-	exported := packagestest.Export(t, exporter, []packagestest.Module{{
-		Name: "golang.org/fake",
-		Files: map[string]interface{}{
-			"c/c.go": `package c; import "C"`,
-		},
-	}})
-
-	// Explicitly enable cgo.
-	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1")
-
-	modes := []packages.LoadMode{
-		packages.NeedTypes,
-		packages.NeedName | packages.NeedTypes,
-		packages.NeedName | packages.NeedTypes | packages.NeedImports,
-		packages.NeedName | packages.NeedTypes | packages.NeedImports | packages.NeedDeps,
-		packages.NeedName | packages.NeedImports,
-	}
-	for _, mode := range modes {
-		t.Run(fmt.Sprint(mode), func(t *testing.T) {
-			exported.Config.Mode = mode
-			pkgs, err := packages.Load(exported.Config, "golang.org/fake/c")
-			if err != nil {
-				t.Fatal(err)
-			}
-			if len(pkgs) != 1 {
-				t.Fatalf("Expected 1 package, got %v", pkgs)
-			}
-			pkg := pkgs[0]
-			if len(pkg.Errors) != 0 {
-				t.Fatalf("Expected no errors in package, got %v", pkg.Errors)
-			}
-		})
-	}
-}
-
 func errorMessages(errors []packages.Error) []string {
 	var msgs []string
 	for _, err := range errors {

go/packages/packagescgo_test.go

@@ -7,11 +7,14 @@
 package packages_test
 
 import (
+	"fmt"
+	"os"
 	"runtime"
 	"strings"
 	"testing"
 
 	"golang.org/x/tools/go/packages"
+	"golang.org/x/tools/go/packages/packagestest"
 	"golang.org/x/tools/internal/testenv"
 )
 
@@ -62,3 +65,71 @@ func TestLoadImportsC(t *testing.T) {
 		}
 	}
 }
+
+func TestCgoNoSyntax(t *testing.T) {
+	packagestest.TestAll(t, testCgoNoSyntax)
+}
+
+// Stolen from internal/testenv package in core.
+// hasGoBuild reports whether the current system can build programs with ``go build''
+// and then run them with os.StartProcess or exec.Command.
+func hasGoBuild() bool {
+	if os.Getenv("GO_GCFLAGS") != "" {
+		// It's too much work to require every caller of the go command
+		// to pass along "-gcflags="+os.Getenv("GO_GCFLAGS").
+		// For now, if $GO_GCFLAGS is set, report that we simply can't
+		// run go build.
+		return false
+	}
+	switch runtime.GOOS {
+	case "android", "js":
+		return false
+	case "darwin":
+		if strings.HasPrefix(runtime.GOARCH, "arm") {
+			return false
+		}
+	}
+	return true
+}
+
+func testCgoNoSyntax(t *testing.T, exporter packagestest.Exporter) {
+	// The android builders have a complex setup which causes this test to fail. See discussion on
+	// golang.org/cl/214943 for more details.
+	if !hasGoBuild() {
+		t.Skip("this test can't run on platforms without go build. See discussion on golang.org/cl/214943 for more details.")
+	}
+
+	exported := packagestest.Export(t, exporter, []packagestest.Module{{
+		Name: "golang.org/fake",
+		Files: map[string]interface{}{
+			"c/c.go": `package c; import "C"`,
+		},
+	}})
+
+	// Explicitly enable cgo.
+	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1")
+
+	modes := []packages.LoadMode{
+		packages.NeedTypes,
+		packages.NeedName | packages.NeedTypes,
+		packages.NeedName | packages.NeedTypes | packages.NeedImports,
+		packages.NeedName | packages.NeedTypes | packages.NeedImports | packages.NeedDeps,
+		packages.NeedName | packages.NeedImports,
+	}
+	for _, mode := range modes {
+		t.Run(fmt.Sprint(mode), func(t *testing.T) {
+			exported.Config.Mode = mode
+			pkgs, err := packages.Load(exported.Config, "golang.org/fake/c")
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(pkgs) != 1 {
+				t.Fatalf("Expected 1 package, got %v", pkgs)
+			}
+			pkg := pkgs[0]
+			if len(pkg.Errors) != 0 {
+				t.Fatalf("Expected no errors in package, got %v", pkg.Errors)
+			}
+		})
+	}
+}