add tests for json module

library/modules/json_test.go

@@ -0,0 +1,39 @@
+package modules
+
+import (
+	"testing"
+
+	"ghostlang.org/x/ghost/object"
+	"ghostlang.org/x/ghost/token"
+	"github.com/shopspring/decimal"
+)
+
+func TestJsonDecode(t *testing.T) {
+	input := `{"name": "John", "age": 30, "city": "New York"}`
+
+	expected := &object.Map{Pairs: map[object.MapKey]object.MapPair{
+		(&object.String{Value: "name"}).MapKey(): {Key: &object.String{Value: "name"}, Value: &object.String{Value: "Kai"}},
+		(&object.String{Value: "age"}).MapKey():  {Key: &object.String{Value: "age"}, Value: &object.Number{Value: decimal.NewFromInt(34)}},
+	}}
+
+	result := jsonDecode(nil, token.Token{}, &object.String{Value: input})
+
+	if result.Type() != expected.Type() {
+		t.Errorf("wrong result type. got=%s, expected=%s", result.Type(), expected.Type())
+	}
+}
+
+func TestJsonEncode(t *testing.T) {
+	input := &object.Map{Pairs: map[object.MapKey]object.MapPair{
+		(&object.String{Value: "name"}).MapKey(): {Key: &object.String{Value: "name"}, Value: &object.String{Value: "Kai"}},
+		(&object.String{Value: "age"}).MapKey():  {Key: &object.String{Value: "age"}, Value: &object.Number{Value: decimal.NewFromInt(34)}},
+	}}
+
+	expected := `{"age":34,"name":"Kai"}`
+
+	result := jsonEncode(nil, token.Token{}, input)
+
+	if result.String() != expected {
+		t.Errorf("wrong result. got=%s, expected=%s", result.String(), expected)
+	}
+}