my sql example added

Author: SergeyPirogov

tests/examples/mysql_example.py

@@ -1,9 +1,18 @@
+import pytest
+import sqlalchemy
+
 from testcontainers import MySqlContainer
 
 
-def example_with_mysql():
-    mysql = MySqlContainer().start()
+@pytest.fixture(scope="session")
+def mysql():
+    mysql = MySqlContainer('mysql:5.7.17').start()
+    engine = sqlalchemy.create_engine(mysql.get_connection_url())
+    yield engine
     mysql.stop()
 
 
-example_with_mysql()
+def test_with_mysql(mysql):
+    result = mysql.execute("select version()")
+    for row in result:
+        assert row[0] == '5.7.17'