PYTHON-1793 Use _id:1 in countDocuments to follow the updated CRUD spec

Author: ShaneHarvey

pymongo/collection.py

@@ -1676,7 +1676,7 @@ def count_documents(self, filter, session=None, **kwargs):
  pipeline.append({'$skip': kwargs.pop('skip')})
  if 'limit' in kwargs:
  pipeline.append({'$limit': kwargs.pop('limit')})
- pipeline.append({'$group': {'_id': None, 'n': {'$sum': 1}}})
+ pipeline.append({'$group': {'_id': 1, 'n': {'$sum': 1}}})
  cmd = SON([('aggregate', self.__name),
  ('pipeline', pipeline),
  ('cursor', {})])

test/transactions/mongos-recovery-token.json

@@ -265,7 +265,7 @@
  "description": "commitTransaction retry fails on new mongos",
  "useMultipleMongoses": true,
  "clientOptions": {
- "heartbeatFrequencyMS": 5000
+ "heartbeatFrequencyMS": 30000
  },
  "operations": [
  {

test/transactions/pin-mongos.json

@@ -1068,7 +1068,7 @@
  "description": "unpin after transient error within a transaction and commit",
  "useMultipleMongoses": true,
  "clientOptions": {
- "heartbeatFrequencyMS": 5000
+ "heartbeatFrequencyMS": 30000
  },
  "operations": [
  {

test/transactions/read-concern.json

@@ -90,7 +90,7 @@
  },
  {
  "$group": {
- "_id": null,
+ "_id": 1,
  "n": {
  "$sum": 1
  }
@@ -126,7 +126,7 @@
  },
  {
  "$group": {
- "_id": null,
+ "_id": 1,
  "n": {
  "$sum": 1
  }
@@ -900,7 +900,7 @@
  },
  {
  "$group": {
- "_id": null,
+ "_id": 1,
  "n": {
  "$sum": 1
  }
@@ -934,7 +934,7 @@
  },
  {
  "$group": {
- "_id": null,
+ "_id": 1,
  "n": {
  "$sum": 1
  }