use statement factory

Author: Kareem Zidane

src/cs50/_statement.py

@@ -16,14 +16,23 @@
 )
 
 
+def statement_factory(dialect):
+    sql_sanitizer = SQLSanitizer(dialect)
+
+    def statement(sql, *args, **kwargs):
+        return Statement(sql_sanitizer, sql, *args, **kwargs)
+
+    return statement
+
+
 class Statement:
     """Parses a SQL statement and replaces the placeholders with the corresponding parameters"""
 
-    def __init__(self, dialect, sql, *args, **kwargs):
+    def __init__(self, sql_sanitizer, sql, *args, **kwargs):
         if len(args) > 0 and len(kwargs) > 0:
             raise RuntimeError("cannot pass both positional and named parameters")
 
-        self._sql_sanitizer = SQLSanitizer(dialect)
+        self._sql_sanitizer = sql_sanitizer
 
         self._args = self._get_escaped_args(args)
         self._kwargs = self._get_escaped_kwargs(kwargs)

src/cs50/sql.py

@@ -7,7 +7,7 @@
 import termcolor
 
 from ._session import Session
-from ._statement import Statement
+from ._statement import statement_factory
 from ._sql_util import fetch_select_result
 
 _logger = logging.getLogger("cs50")
@@ -18,13 +18,14 @@ class SQL:
 
     def __init__(self, url, **engine_kwargs):
         self._session = Session(url, **engine_kwargs)
-        self._dialect = self._session.get_bind().dialect
-        self._is_postgres = self._dialect.name in {"postgres", "postgresql"}
+        dialect = self._session.get_bind().dialect
+        self._is_postgres = dialect.name in {"postgres", "postgresql"}
+        self._sanitized_statement = statement_factory(dialect)
         self._autocommit = False
 
     def execute(self, sql, *args, **kwargs):
         """Execute a SQL statement."""
-        statement = Statement(self._dialect, sql, *args, **kwargs)
+        statement = self._sanitized_statement(sql, *args, **kwargs)
         if statement.is_transaction_start():
             self._autocommit = False
 
@@ -53,7 +54,6 @@ def execute(self, sql, *args, **kwargs):
 
         return ret
 
-
     def _execute(self, statement):
         # Catch SQLAlchemy warnings
         with warnings.catch_warnings():

tests/test_cs50.py

@@ -14,34 +14,29 @@ def test_get_string_empty_input(self, mock_get_input):
         self.assertEqual(get_string("Answer: "), "")
         mock_get_input.assert_called_with("Answer: ")
 
-
     @patch("cs50.cs50._get_input", return_value="test")
     def test_get_string_nonempty_input(self, mock_get_input):
         """Returns the provided non-empty input"""
         self.assertEqual(get_string("Answer: "), "test")
         mock_get_input.assert_called_with("Answer: ")
 
-
     @patch("cs50.cs50._get_input", side_effect=EOFError)
     def test_get_string_eof(self, mock_get_input):
         """Returns None on EOF"""
         self.assertIs(get_string("Answer: "), None)
         mock_get_input.assert_called_with("Answer: ")
 
-
     def test_get_string_invalid_prompt(self):
         """Raises TypeError when prompt is not str"""
         with self.assertRaises(TypeError):
             get_string(1)
 
-
     @patch("cs50.cs50.get_string", return_value=None)
     def test_get_int_eof(self, mock_get_string):
         """Returns None on EOF"""
         self.assertIs(_get_int("Answer: "), None)
         mock_get_string.assert_called_with("Answer: ")
 
-
     def test_get_int_valid_input(self):
         """Returns the provided integer input"""
 
@@ -62,7 +57,6 @@ def assert_equal(return_value, expected_value):
         for return_value, expected_value in values:
             assert_equal(return_value, expected_value)
 
-
     def test_get_int_invalid_input(self):
         """Raises ValueError when input is invalid base-10 int"""
 
@@ -90,14 +84,12 @@ def assert_raises_valueerror(return_value):
         for return_value in return_values:
             assert_raises_valueerror(return_value)
 
-
     @patch("cs50.cs50.get_string", return_value=None)
     def test_get_float_eof(self, mock_get_string):
         """Returns None on EOF"""
         self.assertIs(_get_float("Answer: "), None)
         mock_get_string.assert_called_with("Answer: ")
 
-
     def test_get_float_valid_input(self):
         """Returns the provided integer input"""
         def assert_equal(return_value, expected_value):
@@ -121,7 +113,6 @@ def assert_equal(return_value, expected_value):
         for return_value, expected_value in values:
             assert_equal(return_value, expected_value)
 
-
     def test_get_float_invalid_input(self):
         """Raises ValueError when input is invalid float"""