Deprecate context manager interface of Connection (PyMySQL#742)

Author: methane

pymysql/connections.py

@@ -492,6 +492,9 @@ def cursor(self, cursor=None):
 
     def __enter__(self):
         """Context manager that returns a Cursor"""
+        warnings.warn(
+            "Context manager API of Connection object is deprecated; Use conn.begin()",
+            DeprecationWarning)
         return self.cursor()
 
     def __exit__(self, exc, value, traceback):

pymysql/tests/test_connection.py

@@ -7,6 +7,8 @@
 from pymysql._compat import text_type
 from pymysql.constants import CLIENT
 
+import pytest
+
 
 class TempUser:
     def __init__(self, c, user, db, auth=None, authdata=None, password=None):
@@ -451,21 +453,23 @@ def test_read_default_group(self):
     def test_context(self):
         with self.assertRaises(ValueError):
             c = self.connect()
+            with pytest.warns(DeprecationWarning):
+                with c as cur:
+                    cur.execute('create table test ( a int ) ENGINE=InnoDB')
+                    c.begin()
+                    cur.execute('insert into test values ((1))')
+                    raise ValueError('pseudo abort')
+        c = self.connect()
+        with pytest.warns(DeprecationWarning):
             with c as cur:
-                cur.execute('create table test ( a int ) ENGINE=InnoDB')
-                c.begin()
+                cur.execute('select count(*) from test')
+                self.assertEqual(0, cur.fetchone()[0])
                 cur.execute('insert into test values ((1))')
-                raise ValueError('pseudo abort')
-                c.commit()
-        c = self.connect()
-        with c as cur:
-            cur.execute('select count(*) from test')
-            self.assertEqual(0, cur.fetchone()[0])
-            cur.execute('insert into test values ((1))')
-        with c as cur:
-            cur.execute('select count(*) from test')
-            self.assertEqual(1,cur.fetchone()[0])
-            cur.execute('drop table test')
+        with pytest.warns(DeprecationWarning):
+            with c as cur:
+                cur.execute('select count(*) from test')
+                self.assertEqual(1,cur.fetchone()[0])
+                cur.execute('drop table test')
 
     def test_set_charset(self):
         c = self.connect()