feature: use environment in addition to flags to control test options

This applies to -syscall, -unsafe and -unrestricted flags with the
corresponding env variables YAEGI_SYSCALL, YAEGI_UNSAFE and
YAEGI_UNRESTRICTED, already used in the same way for the run
sub-command.

cmd/yaegi/test.go

@@ -7,6 +7,7 @@ import (
 	"go/build"
 	"os"
 	"regexp"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -28,13 +29,15 @@ func test(arg []string) (err error) {
 		run       string
 		short     bool
 		tags      string
-		useUnrestricted bool
-		useUnsafe       bool
-		useSyscall      bool
 		timeout   string
 		verbose   bool
 	)
 
+	// The following flags are initialized from environment.
+	useSyscall, _ := strconv.ParseBool(os.Getenv("YAEGI_SYSCALL"))
+	useUnrestricted, _ := strconv.ParseBool(os.Getenv("YAEGI_UNRESTRICTED"))
+	useUnsafe, _ := strconv.ParseBool(os.Getenv("YAEGI_UNSAFE"))
+
 	tflag := flag.NewFlagSet("test", flag.ContinueOnError)
 	tflag.StringVar(&bench, "bench", "", "Run only those benchmarks matching a regular expression.")
 	tflag.BoolVar(&benchmem, "benchmem", false, "Print memory allocation statistics for benchmarks.")
@@ -46,9 +49,9 @@ func test(arg []string) (err error) {
 	tflag.BoolVar(&short, "short", false, "Tell long-running tests to shorten their run time.")
 	tflag.StringVar(&tags, "tags", "", "Set a list of build tags.")
 	tflag.StringVar(&timeout, "timeout", "", "If a test binary runs longer than duration d, panic.")
-	tflag.BoolVar(&useUnrestricted, "unrestricted", false, "Include unrestricted symbols.")
+	tflag.BoolVar(&useUnrestricted, "unrestricted", useUnrestricted, "Include unrestricted symbols.")
-	tflag.BoolVar(&useUnsafe, "unsafe", false, "Include usafe symbols.")
+	tflag.BoolVar(&useUnsafe, "unsafe", useUnsafe, "Include usafe symbols.")
-	tflag.BoolVar(&useSyscall, "syscall", false, "Include syscall symbols.")
+	tflag.BoolVar(&useSyscall, "syscall", useSyscall, "Include syscall symbols.")
 	tflag.BoolVar(&verbose, "v", false, "Verbose output: log all tests as they are run.")
 	tflag.Usage = func() {
 		fmt.Println("Usage: yaegi test [options] [path]")
@@ -105,12 +108,22 @@ func test(arg []string) (err error) {
 	i.Use(interp.Symbols)
 	if useSyscall {
 		i.Use(syscall.Symbols)
+		// Using a environment var allows a nested interpreter to import the syscall package.
+		if err := os.Setenv("YAEGI_SYSCALL", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnrestricted {
 		i.Use(unrestricted.Symbols)
+		if err := os.Setenv("YAEGI_UNRESTRICTED", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnsafe {
 		i.Use(unsafe.Symbols)
+		if err := os.Setenv("YAEGI_UNSAFE", "1"); err != nil {
+			return err
+		}
 	}
 	if err = i.EvalTest(path); err != nil {
 		return err