Add test specifically for the filter() method returning a list

Add a test case for the basic case that a call to a Manager or
QuerySets filter() method returns another QuerySet.

Author: ngtvspc

pylint_django/tests/input/func_noerror_managers_return_querysets.py

@@ -0,0 +1,51 @@
+"""
+Checks that Pylint does not complain about Manager methods returning lists
+when they in fact return QuerySets
+"""
+
+from django.db import models
+
+
+class SomeModelQuerySet(models.QuerySet):
+    """ A missing docstring """
+    @staticmethod
+    def public_method():
+        """ A missing docstring """
+        return 1
+
+
+class SomeModelManager(models.Manager):
+    """A missing docstring"""
+
+    @staticmethod
+    def public_method():
+        """ A missing docstring """
+        return 1
+
+    @staticmethod
+    def another_public_method():
+        """ A missing docstring """
+        return 1
+
+
+class SomeModel(models.Model):
+    """ A missing docstring """
+
+    name = models.CharField(max_length=20)
+    datetimestamp = models.DateTimeField()
+
+    objects = SomeModelManager()
+
+
+class OtherModel(models.Model):
+    """ A missing docstring """
+
+    name = models.CharField(max_length=20)
+    somemodel = models.ForeignKey(SomeModel, on_delete=models.CASCADE, null=False)
+
+
+def call_some_querysets():
+    """ A missing docstring """
+
+    not_a_list = SomeModel.objects.filter()
+    not_a_list.values_list('id', flat=True)