Fix randomization of enum values

- Fix #179

randomize/randomize.go

@@ -159,18 +159,17 @@ func randDate(s *Seed) time.Time {
 // If canBeNull is true:
 //  The value has the possibility of being null or non-zero at random.
 func randomizeField(s *Seed, field reflect.Value, fieldType string, canBeNull bool) error {
-
 	kind := field.Kind()
 	typ := field.Type()
 
 	if strings.HasPrefix(fieldType, "enum") {
-		enum, err := randEnumValue(fieldType)
+		enum, err := randEnumValue(s, fieldType)
 		if err != nil {
 			return err
 		}
 
 		if kind == reflect.Struct {
-			val := null.NewString(enum, rand.Intn(1) == 0)
+			val := null.NewString(enum, s.nextInt()%2 == 0)
 			field.Set(reflect.ValueOf(val))
 		} else {
 			field.Set(reflect.ValueOf(enum))
@@ -623,13 +622,11 @@ func getVariableRandValue(s *Seed, kind reflect.Kind, typ reflect.Type) interfac
 	return nil
 }
 
-func randEnumValue(enum string) (string, error) {
+func randEnumValue(s *Seed, enum string) (string, error) {
 	vals := strmangle.ParseEnumVals(enum)
 	if vals == nil || len(vals) == 0 {
 		return "", fmt.Errorf("unable to parse enum string: %s", enum)
-	} else if len(vals) == 1 {
-		return vals[0], nil
 	}
 
-	return vals[rand.Intn(len(vals)-1)], nil
+	return vals[s.nextInt()%len(vals)], nil
 }

randomize/randomize_test.go

@@ -148,11 +148,13 @@ func TestRandomizeField(t *testing.T) {
 func TestRandEnumValue(t *testing.T) {
 	t.Parallel()
 
+	s := NewSeed()
+
 	enum1 := "enum.workday('monday','tuesday')"
 	enum2 := "enum('monday','tuesday')"
 	enum3 := "enum('monday')"
 
-	r1, err := randEnumValue(enum1)
+	r1, err := randEnumValue(s, enum1)
 	if err != nil {
 		t.Error(err)
 	}
@@ -161,7 +163,7 @@ func TestRandEnumValue(t *testing.T) {
 		t.Errorf("Expected monday or tuesday, got: %q", r1)
 	}
 
-	r2, err := randEnumValue(enum2)
+	r2, err := randEnumValue(s, enum2)
 	if err != nil {
 		t.Error(err)
 	}
@@ -170,7 +172,7 @@ func TestRandEnumValue(t *testing.T) {
 		t.Errorf("Expected monday or tuesday, got: %q", r2)
 	}
 
-	r3, err := randEnumValue(enum3)
+	r3, err := randEnumValue(s, enum3)
 	if err != nil {
 		t.Error(err)
 	}