Update pre-commit and fix existing flake8 warnings once for all

.pre-commit-config.yaml

@@ -1,13 +1,13 @@
+fail_fast: false
 repos:
     - repo: https://github.com/ambv/black
-      rev: 19.3b0
+      rev: 19.10b0
       hooks:
         - id: black
-          language_version: python3
+#          language_version: python3
-
+    - repo: https://gitlab.com/pycqa/flake8
-    - repo: https://github.com/pre-commit/pre-commit-hooks
+      rev: 3.8.0a2
-      rev: v2.2.3
       hooks:
-        - id: trailing-whitespace
-        - id: end-of-file-fixer
         - id: flake8
+          additional_dependencies:
+            - flake8-import-order

.travis.yml

@@ -59,18 +59,16 @@ install:
   # Install Python dependencies.
   - pip install --upgrade pip
   - pip install coveralls
-  - pip install flake8 flake8-import-order
+  - pip install pre-commit
   - pip install tox
   # tox dryrun to setup the tox venv (we run a mock test).
   - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -a "-k=test_ci_placeholder"
-  # Install black for Python v3.7 only.
-  - if [[ $TRAVIS_PYTHON_VERSION == $MAIN_PYTHON_VERSION ]]; then pip install black; fi
 
 before_script:
   - mkdir ${PWD}/mongodb-linux-x86_64-${MONGODB}/data
   - ${PWD}/mongodb-linux-x86_64-${MONGODB}/bin/mongod --dbpath ${PWD}/mongodb-linux-x86_64-${MONGODB}/data --logpath ${PWD}/mongodb-linux-x86_64-${MONGODB}/mongodb.log --fork
-  - if [[ $TRAVIS_PYTHON_VERSION == $MAIN_PYTHON_VERSION ]]; then flake8 .; else echo "flake8 only runs on py37"; fi
+  # Run pre-commit hooks (black, flake8, etc) on entire codebase
-  - if [[ $TRAVIS_PYTHON_VERSION == $MAIN_PYTHON_VERSION ]]; then black --check .; else echo "black only runs on py37"; fi
+  - if [[ $TRAVIS_PYTHON_VERSION == $MAIN_PYTHON_VERSION ]]; then pre-commit run -a; else echo "pre-commit checks only runs on py37"; fi
   - mongo --eval 'db.version();'    # Make sure mongo is awake
 
 script:

tests/document/test_instance.py

@@ -1414,7 +1414,7 @@ class TestDocumentInstance(MongoDBTestCase):
         assert raw_doc["first_name"] == "John"
 
     def test_inserts_if_you_set_the_pk(self):
-        p1 = self.Person(name="p1", id=bson.ObjectId()).save()
+        _ = self.Person(name="p1", id=bson.ObjectId()).save()
         p2 = self.Person(name="p2")
         p2.id = bson.ObjectId()
         p2.save()
@@ -2195,7 +2195,7 @@ class TestDocumentInstance(MongoDBTestCase):
 
         user = User(name="Mike").save()
         reviewer = User(name="John").save()
-        book = Book(author=user, reviewer=reviewer).save()
+        _ = Book(author=user, reviewer=reviewer).save()
 
         reviewer.delete()
         assert Book.objects.count() == 1
@@ -2221,7 +2221,7 @@ class TestDocumentInstance(MongoDBTestCase):
 
         user_1 = User(id=1).save()
         user_2 = User(id=2).save()
-        book_1 = Book(id=1, author=user_2).save()
+        _ = Book(id=1, author=user_2).save()
         book_2 = Book(id=2, author=user_1).save()
 
         user_2.delete()
@@ -2230,7 +2230,7 @@ class TestDocumentInstance(MongoDBTestCase):
         assert Book.objects.get() == book_2
 
         user_3 = User(id=3).save()
-        book_3 = Book(id=3, author=user_3).save()
+        _ = Book(id=3, author=user_3).save()
 
         user_3.delete()
         # Deleting user_3 should also delete book_3
@@ -3204,7 +3204,7 @@ class TestDocumentInstance(MongoDBTestCase):
     def test_positional_creation(self):
         """Document cannot be instantiated using positional arguments."""
         with pytest.raises(TypeError) as exc_info:
-            person = self.Person("Test User", 42)
+            self.Person("Test User", 42)
 
         expected_msg = (
             "Instantiating a document with positional arguments is not "
@@ -3606,13 +3606,13 @@ class TestDocumentInstance(MongoDBTestCase):
             v = StringField()
 
         class A(Document):
-            l = ListField(EmbeddedDocumentField(B))
+            array = ListField(EmbeddedDocumentField(B))
 
         A.objects.delete()
-        A(l=[B(v="1"), B(v="2"), B(v="3")]).save()
+        A(array=[B(v="1"), B(v="2"), B(v="3")]).save()
         a = A.objects.get()
-        assert a.l._instance == a
+        assert a.array._instance == a
-        for idx, b in enumerate(a.l):
+        for idx, b in enumerate(a.array):
             assert b._instance == a
         assert idx == 2
 

tests/fields/test_dict_field.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
-import pytest
 from bson import InvalidDocument
+import pytest
 
 from mongoengine import *
 from mongoengine.base import BaseDict

tests/fields/test_lazy_reference_field.py

@@ -152,7 +152,7 @@ class TestLazyReferenceField(MongoDBTestCase):
             LazyReference(BadDoc, animal.pk),
         ):
             with pytest.raises(ValidationError):
-                p = Ocurrence(person="test", animal=bad).save()
+                Ocurrence(person="test", animal=bad).save()
 
     def test_lazy_reference_query_conversion(self):
         """Ensure that LazyReferenceFields can be queried using objects and values
@@ -386,7 +386,7 @@ class TestGenericLazyReferenceField(MongoDBTestCase):
         mineral = Mineral(name="Granite").save()
 
         occ_animal = Ocurrence(living_thing=animal, thing=animal).save()
-        occ_vegetal = Ocurrence(living_thing=vegetal, thing=vegetal).save()
+        _ = Ocurrence(living_thing=vegetal, thing=vegetal).save()
         with pytest.raises(ValidationError):
             Ocurrence(living_thing=mineral).save()
 
@@ -458,7 +458,7 @@ class TestGenericLazyReferenceField(MongoDBTestCase):
         baddoc = BadDoc().save()
         for bad in (42, "foo", baddoc, LazyReference(BadDoc, animal.pk)):
             with pytest.raises(ValidationError):
-                p = Ocurrence(person="test", animal=bad).save()
+                Ocurrence(person="test", animal=bad).save()
 
     def test_generic_lazy_reference_query_conversion(self):
         class Member(Document):

tests/queryset/test_queryset.py

@@ -116,7 +116,7 @@ class TestQueryset(unittest.TestCase):
     def test_limit(self):
         """Ensure that QuerySet.limit works as expected."""
         user_a = self.Person.objects.create(name="User A", age=20)
-        user_b = self.Person.objects.create(name="User B", age=30)
+        _ = self.Person.objects.create(name="User B", age=30)
 
         # Test limit on a new queryset
         people = list(self.Person.objects.limit(1))
@@ -148,6 +148,11 @@ class TestQueryset(unittest.TestCase):
         user_b = self.Person.objects.create(name="User B", age=30)
 
         # Test skip on a new queryset
+        people = list(self.Person.objects.skip(0))
+        assert len(people) == 2
+        assert people[0] == user_a
+        assert people[1] == user_b
+
         people = list(self.Person.objects.skip(1))
         assert len(people) == 1
         assert people[0] == user_b
@@ -2586,13 +2591,8 @@ class TestQueryset(unittest.TestCase):
             age = IntField()
 
         with db_ops_tracker() as q:
-            adult1 = (
             User.objects.filter(age__gte=18).comment("looking for an adult").first()
-            )
-
-            adult2 = (
             User.objects.comment("looking for an adult").filter(age__gte=18).first()
-            )
 
             ops = q.get_ops()
             assert len(ops) == 2
@@ -4518,7 +4518,7 @@ class TestQueryset(unittest.TestCase):
 
         foos_without_y = list(Foo.objects.order_by("y").fields(y=0))
 
-        assert all(o.y is None for o in foos_with_x)
+        assert all(o.y is None for o in foos_without_y)
 
         foos_with_sliced_items = list(Foo.objects.order_by("y").fields(slice__items=1))
 
@@ -5595,7 +5595,7 @@ class TestQueryset(unittest.TestCase):
         self.Person.objects.create(name="Baz")
         assert self.Person.objects.count(with_limit_and_skip=True) == 3
 
-        newPerson = self.Person.objects.create(name="Foo_1")
+        self.Person.objects.create(name="Foo_1")
         assert self.Person.objects.count(with_limit_and_skip=True) == 4
 
     def test_no_cursor_timeout(self):

tests/test_connection.py

@@ -348,7 +348,7 @@ class ConnectionTest(unittest.TestCase):
 
     def test_disconnect_cleans_cached_collection_attribute_in_document(self):
         """Ensure that the disconnect() method works properly"""
-        conn1 = connect("mongoenginetest")
+        connect("mongoenginetest")
 
         class History(Document):
             pass
@@ -518,7 +518,7 @@ class ConnectionTest(unittest.TestCase):
         """Ensure connect() uses the username & password params if the URI
         doesn't explicitly specify them.
         """
-        c = connect(
+        connect(
             host="mongodb://localhost/mongoenginetest", username="user", password="pass"
         )
 
@@ -632,7 +632,7 @@ class ConnectionTest(unittest.TestCase):
         """Ensure connect() works when specifying a replicaSet via the
         MongoDB URI.
         """
-        c = connect(host="mongodb://localhost/test?replicaSet=local-rs")
+        connect(host="mongodb://localhost/test?replicaSet=local-rs")
         db = get_db()
         assert isinstance(db, pymongo.database.Database)
         assert db.name == "test"

tests/test_context_managers.py

@@ -216,7 +216,7 @@ class TestContextManagers:
 
     def test_query_counter_does_not_swallow_exception(self):
         with pytest.raises(TypeError):
-            with query_counter() as q:
+            with query_counter():
                 raise TypeError()
 
     def test_query_counter_temporarily_modifies_profiling_level(self):
@@ -226,12 +226,12 @@ class TestContextManagers:
         initial_profiling_level = db.profiling_level()
 
         try:
-            NEW_LEVEL = 1
+            new_level = 1
-            db.set_profiling_level(NEW_LEVEL)
+            db.set_profiling_level(new_level)
-            assert db.profiling_level() == NEW_LEVEL
+            assert db.profiling_level() == new_level
-            with query_counter() as q:
+            with query_counter():
                 assert db.profiling_level() == 2
-            assert db.profiling_level() == NEW_LEVEL
+            assert db.profiling_level() == new_level
         except Exception:
             db.set_profiling_level(
                 initial_profiling_level

tests/test_signals.py

@@ -267,7 +267,7 @@ class TestSignal(unittest.TestCase):
             a = self.Author(name="Bill Shakespeare")
             a.save()
             self.get_signal_output(lambda: None)  # eliminate signal output
-            a1 = self.Author.objects(name="Bill Shakespeare")[0]
+            _ = self.Author.objects(name="Bill Shakespeare")[0]
 
         assert self.get_signal_output(create_author) == [
             "pre_init signal, Author",