Allow fields to be a set (mongodb#347)

rdb · ShaneHarvey · commit 077fb2041a2d · 2018-02-12T11:33:36.000-08:00
Add test cases for set and tuple projection arguments.
diff --git a/pymongo/helpers.py b/pymongo/helpers.py
@@ -235,7 +235,7 @@ def _fields_list_to_dict(fields, option_name):
     if isinstance(fields, collections.Mapping):
         return fields
 
-    if isinstance(fields, collections.Sequence):
+    if isinstance(fields, (collections.Sequence, collections.Set)):
         if not all(isinstance(field, string_type) for field in fields):
             raise TypeError("%s must be a list of key names, each an "
                             "instance of %s" % (option_name,
diff --git a/test/test_collection.py b/test/test_collection.py
@@ -1743,6 +1743,16 @@ def test_find_one(self):
 
         self.assertTrue("hello" in db.test.find_one(projection=["hello"]))
         self.assertTrue("hello" not in db.test.find_one(projection=["foo"]))
+
+        self.assertTrue("hello" in db.test.find_one(projection=("hello",)))
+        self.assertTrue("hello" not in db.test.find_one(projection=("foo",)))
+
+        self.assertTrue("hello" in db.test.find_one(projection=set(["hello"])))
+        self.assertTrue("hello" not in db.test.find_one(projection=set(["foo"])))
+
+        self.assertTrue("hello" in db.test.find_one(projection=frozenset(["hello"])))
+        self.assertTrue("hello" not in db.test.find_one(projection=frozenset(["foo"])))
+
         self.assertEqual(["_id"], list(db.test.find_one(projection=[])))
 
         self.assertEqual(None, db.test.find_one({"hello": "foo"}))
