fix: properly handle explicitly passing default namespace (googleapis#488)

Fixes googleapis#476.

Author: Chris Rossi

google/cloud/ndb/query.py

@@ -1281,7 +1281,7 @@ def __init__(self, config=None, context=None, **kwargs):
             if not self.project:
                 self.project = context.client.project
 
-            if not self.namespace:
+            if self.namespace is None:
                 self.namespace = context.get_namespace()
 
 

tests/system/conftest.py

@@ -16,6 +16,18 @@
 log = logging.getLogger(__name__)
 
 
+@pytest.fixture(scope="session", autouse=True)
+def preclean():
+    """Clean out default namespace in test database."""
+    ds_client = _make_ds_client(None)
+    for kind in (KIND, OTHER_KIND):
+        query = ds_client.query(kind=kind)
+        query.keys_only()
+        for page in query.fetch().pages:
+            keys = [entity.key for entity in page]
+            ds_client.delete_multi(keys)
+
+
 def _make_ds_client(namespace):
     emulator = bool(os.environ.get("DATASTORE_EMULATOR_HOST"))
     if emulator:

tests/system/test_query.py

@@ -315,6 +315,39 @@ class SomeKind(ndb.Model):
         assert results[0].key.namespace() == other_namespace
 
 
+def test_query_default_namespace_when_context_namespace_is_other(
+    client_context, dispose_of, other_namespace
+):
+    """Regression test for #476.
+
+    https://github.com/googleapis/python-ndb/issues/476
+    """
+
+    class SomeKind(ndb.Model):
+        foo = ndb.IntegerProperty()
+        bar = ndb.StringProperty()
+
+    entity1 = SomeKind(foo=1, bar="a", id="x", namespace=other_namespace)
+    entity1.put()
+    dispose_of(entity1.key._key)
+
+    entity2 = SomeKind(foo=2, bar="b", id="x", namespace="")
+    entity2.put()
+    dispose_of(entity2.key._key)
+
+    eventually(
+        SomeKind.query(namespace=other_namespace).fetch, length_equals(1)
+    )
+
+    with client_context.new(namespace=other_namespace).use():
+        query = SomeKind.query(namespace="")
+        results = eventually(query.fetch, length_equals(1))
+
+    assert results[0].foo == 2
+    assert results[0].bar == "b"
+    assert results[0].key.namespace() is None
+
+
 @pytest.mark.usefixtures("client_context")
 def test_filter_equal(ds_entity):
     for i in range(5):

tests/unit/test_query.py

@@ -89,6 +89,12 @@ def test_copy():
         assert options.project == "app2"
         assert options.namespace == "foo"
 
+    @staticmethod
+    def test_explicitly_set_default_namespace(in_context):
+        with in_context.new(namespace="somethingelse").use() as context:
+            options = query_module.QueryOptions(context=context, namespace="")
+            assert options.namespace == ""
+
 
 class TestPropertyOrder:
     @staticmethod