PYTHON-2019 Add support for validate command "background" option

Author: ShaneHarvey

doc/changelog.rst

@@ -11,6 +11,11 @@ Version 3.11 adds support for MongoDB 4.4. Highlights include:
   alternative TLS implementation. PyOpenSSL is required for :ref:`OCSP`
   support. It will also be installed when using the "tls" extra if the
   version of Python in use is older than 2.7.9.
+- Added the ``background`` parameter to
+  :meth:`pymongo.database.Database.validate_collection`. For a description
+  of this parameter see the MongoDB documentation for the `validate command`_.
+
+.. _validate command: https://docs.mongodb.com/manual/reference/command/validate/
 
 Issues Resolved
 ...............

pymongo/database.py

@@ -921,12 +921,15 @@ def drop_collection(self, name_or_collection, session=None):
                 session=session)
 
     def validate_collection(self, name_or_collection,
-                            scandata=False, full=False, session=None):
+                            scandata=False, full=False, session=None,
+                            background=None):
         """Validate a collection.
 
         Returns a dict of validation info. Raises CollectionInvalid if
         validation fails.
 
+        See also the MongoDB documentation on the `validate command`_.
+
         :Parameters:
           - `name_or_collection`: A Collection object or the name of a
             collection to validate.
@@ -938,9 +941,16 @@ def validate_collection(self, name_or_collection,
             documents.
           - `session` (optional): a
             :class:`~pymongo.client_session.ClientSession`.
+          - `background` (optional): A boolean flag that determines whether
+            the command runs in the background. Requires MongoDB 4.4+.
+
+        .. versionchanged:: 3.11
+           Added ``background`` parameter.
 
         .. versionchanged:: 3.6
            Added ``session`` parameter.
+
+        .. _validate command: https://docs.mongodb.com/manual/reference/command/validate/
         """
         name = name_or_collection
         if isinstance(name, Collection):
@@ -950,8 +960,13 @@ def validate_collection(self, name_or_collection,
             raise TypeError("name_or_collection must be an instance of "
                             "%s or Collection" % (string_type.__name__,))
 
-        result = self.command("validate", _unicode(name),
-                              scandata=scandata, full=full, session=session)
+        cmd = SON([("validate", _unicode(name)),
+                   ("scandata", scandata),
+                   ("full", full)])
+        if background is not None:
+            cmd["background"] = background
+
+        result = self.command(cmd, session=session)
 
         valid = True
         # Pre 1.9 results

test/test_database.py

@@ -367,6 +367,16 @@ def test_validate_collection(self):
         self.assertTrue(db.validate_collection(db.test, scandata=True))
         self.assertTrue(db.validate_collection(db.test, scandata=True, full=True))
         self.assertTrue(db.validate_collection(db.test, True, True))
+        if client_context.version.at_least(4, 3, 3):
+            self.assertTrue(db.validate_collection(db.test, background=True))
+            self.assertTrue(db.validate_collection(db.test, background=False))
+            self.assertTrue(
+                db.validate_collection(db.test, scandata=True, background=True))
+            # The server does not support background=True with full=True.
+            # Assert that we actually send the background option by checking
+            # that this combination fails.
+            with self.assertRaises(OperationFailure):
+                db.validate_collection(db.test, full=True, background=True)
 
     @client_context.require_no_mongos
     def test_profiling_levels(self):