fix(json): Fix keys not being escaped correctly in json.dumps

Fixes #15

src/polyfills/json/__init__.py

@@ -15,6 +15,20 @@
 
 __all__ = ["dumps", "dump", "loads", "load"]
 
+def escape_string(string):
+    # type: (str) -> str
+    """Escapes a string so that it can be used as a JSON string.
+
+    Args:
+        string (str): The string to escape.
+
+    Returns:
+        str: The escaped string.
+    """
+    return string \
+        .replace("\\", "\\\\") \
+        .replace('"', '\\"')
+
 def dumps(
         obj,
         indent=None,          # type: int|None
@@ -58,7 +72,17 @@ def dumps(
             if len(obj_string_parts) > 1:
                 obj_string_parts[-1] += ", "
             value = dumps(obj[key], indent_spaces, truthy_value, falsy_value)
-            obj_string_parts.append('"%s": %s' % (str(key), str(value)))
+            parsed_key = dumps(key)
+
+            # Remove quotes from the parsed key, because we will add them
+            #   manually later.
+            if parsed_key.startswith('"') and parsed_key.endswith('"'):
+                parsed_key = parsed_key[1:-1]
+
+            obj_string_parts.append('"%s": %s' % (
+                parsed_key,
+                str(value),
+            ))
 
         obj_string_parts.append("}")
     #endif
@@ -111,7 +135,7 @@ def dumps(
 
         # ---> Base types
         elif obj_type == type(""):
-            return '"%s"' % str(obj).replace("\\", "\\\\").replace('"', '\\"')
+            return '"%s"' % escape_string(str(obj))
         elif obj_type == type(5):
             return str(obj)
         elif obj_type == type(5.0):

src/polyfills/json/tests/dumps/test_dumps.py

@@ -117,6 +117,43 @@ def test_simple(self):
             '{"key": "value"}'
         )
 
+    def test_conversion_keys(self):
+        self.assertEqual(
+            json.dumps({True: 1, False: 0, None: "null"}),
+            '{"true": 1, "false": 0, "null": "null"}'
+        )
+
+    def test_quotes(self):
+        """ Quotes should be escaped (see #15) """
+        self.assertEqual(
+            json.dumps({"\"": "\""}),
+            r'{"\"": "\""}',
+            "Double quotes should be escaped both in keys and values"
+        )
+        self.assertEqual(
+            json.dumps({"'": "'"}),
+            r"""{"'": "'"}""",
+            "Single quotes should be kept as-is",
+        )
+
+
+    def test_escape(self):
+        self.assertEqual(
+            json.dumps({"key": "va'lue"}),
+            r"""{"key": "va'lue"}""",
+            "Single quotes do not need to be escaped"
+        )
+        self.assertEqual(
+            json.dumps({'k"ey': 'va"lue'}),
+            r"""{"k\"ey": "va\"lue"}""",
+            "Double quotes should be escaped"
+        )
+        self.assertEqual(
+            json.dumps({r"k\ey": r"va\lue"}),
+            r"""{"k\\ey": "va\\lue"}""",
+            "Backslashes should be escaped both in keys and values"
+        )
+
     def test_complex(self):
         if str(1==1) == 'True':
             __true__ = 1==1