Allow Connection subclasses for backups

Fixes issue #199

doc/changes.rst

@@ -17,6 +17,8 @@ Added SQLITE_INDEX_CONSTRAINT_LIKE, SQLITE_INDEX_CONSTRAINT_REGEXP,
 SQLITE_INDEX_CONSTRAINT_GLOB,SQLITE_IOERR_AUTH, SQLITE_FCNTL_JOURNAL_POINTER,
 and SQLITE_FCNTL_VFS_POINTER constants.
 
+Allow :class:`Connection` subclasses for backup api (:issue:`199`).
+
 3.9.2-r1
 ========
 

src/connection.c

@@ -591,7 +591,7 @@ Connection_backup(Connection *self, PyObject *args)
                        STRENCODING, &databasename, &source, STRENCODING, &sourcedatabasename))
     return NULL;
 
-  if(Py_TYPE(source)!=&ConnectionType)
+  if(!PyObject_IsInstance((PyObject*)source, (PyObject*)&ConnectionType))
     {
       PyErr_Format(PyExc_TypeError, "source connection needs to be a Connection instance");
       goto finally;

tests.py

@@ -3341,6 +3341,19 @@ def dummy(x,y):
         self.db.createcollation("dummy", None)
         self.assertRaises(apsw.SQLError, cur.execute, "select * from foo order by x collate dummy")
 
+    def testIssue199(self):
+        "Backup API should accept Connection subclasses"
+        # https://github.com/rogerbinns/apsw/issues/199
+        class subclass(apsw.Connection):
+            pass
+
+        dbsub=subclass("")
+        dbsub.cursor().execute("create table a(b);insert into a values(3);")
+
+        with self.db.backup("main", dbsub, "main") as b:
+            while not b.done:
+                b.step(100)
+
     def testPysqliteRecursiveIssue(self):
         "Check an issue that affected pysqlite"
         # https://code.google.com/p/pysqlite/source/detail?r=260ee266d6686e0f87b0547c36b68a911e6c6cdb