fix(tracing): fix error when using sqlite3 backup method (backport #4246)

ddtrace/contrib/sqlite3/patch.py

@@ -1,6 +1,7 @@
 import os
 import sqlite3
 import sqlite3.dbapi2
+import sys
 
 from ddtrace import config
 from ddtrace.vendor import wrapt
@@ -75,3 +76,13 @@ def __init__(self, conn, pin=None, cursor_cls=None):
     def execute(self, *args, **kwargs):
         # sqlite has a few extra sugar functions
         return self.cursor().execute(*args, **kwargs)
+
+    # backup was added in Python 3.7
+    if sys.version_info >= (3, 7, 0):
+
+        def backup(self, target, *args, **kwargs):
+            # sqlite3 checks the type of `target`, it cannot be a wrapped connection
+            # https://github.com/python/cpython/blob/4652093e1b816b78e9a585d671a807ce66427417/Modules/_sqlite/connection.c#L1897-L1899
+            if isinstance(target, TracedConnection):
+                target = target.__wrapped__
+            return self.__wrapped__.backup(target, *args, **kwargs)

releasenotes/notes/fix-sqlite3-backup-bf92c698567237b9.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    sqlite3: fix error when using ``connection.backup`` method.

tests/contrib/sqlite3/test_sqlite3.py

@@ -1,4 +1,5 @@
 import sqlite3
+import sys
 import time
 
 import pytest
@@ -351,3 +352,21 @@ def test_context_manager(self):
             cursor.fetchall()
             spans = self.get_spans()
             assert len(spans) == 1
+<<<<<<< HEAD
+=======
+
+
+def test_iterator_usage(patched_conn):
+    """Ensure sqlite3 patched cursors can be used as iterators."""
+    rows = next(patched_conn.execute("select 1"))
+    assert len(rows) == 1
+
+
+@pytest.mark.skipif(sys.version_info < (3, 7), reason="Connection.backup was added in Python 3.7")
+def test_backup(patched_conn):
+    """Ensure sqlite3 patched connections backup function can be used"""
+    destination = sqlite3.connect(":memory:")
+
+    with destination:
+        patched_conn.backup(destination, pages=1)
+>>>>>>> 82b15216 (fix(tracing): fix error when using sqlite3 backup method (#4246))