Add a fake __eq__ method to relationship() to avoid false positives with --strict-equality (#92)

Author: ilevkivskyi

sqlalchemy-stubs/orm/relationships.pyi

@@ -87,6 +87,8 @@ class RelationshipProperty(StrategizedProperty, Generic[_T_co]):
         def __ne__(self, other): ...
         @property
         def property(self): ...
+    # This doesn't exist at runtime, and Comparator is used instead, but it is hard to explain to mypy.
+    def __eq__(self, other: Any) -> Any: ...
     def merge(self, session, source_state, source_dict, dest_state, dest_dict,
               load, _recursive, _resolve_conflict_map): ...
     def cascade_iterator(self, *args, **kwargs): ...

test/test-data/sqlalchemy-basics.test

@@ -120,3 +120,26 @@ user = User()
 reveal_type(user.id)  # N: Revealed type is 'builtins.int*'
 reveal_type(User.name)  # N: Revealed type is 'sqlalchemy.sql.schema.Column[builtins.unicode*]'
 [out]
+
+[case testRelationshipStrictEquality]
+# flags: --strict-equality
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy import Column, Integer, String
+from sqlalchemy.orm import relationship
+from sqlalchemy.orm import Session
+
+Base = declarative_base()
+session = Session()
+
+class User(Base):
+    __tablename__ = 'users'
+    id = Column(Integer(), primary_key=True)
+    other = relationship('Other')
+
+class Other(Base):
+    __tablename__ = 'other'
+    id = Column(Integer(), primary_key=True)
+
+other: Other
+session.query(User).filter(User.other == other)
+[out]

test/testsql.py

@@ -3,6 +3,7 @@
 import os
 import os.path
 import sys
+import re
 
 import pytest  # type: ignore  # no pytest in typeshed
 
@@ -54,6 +55,12 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
                 version = sys.version_info[:2]
             mypy_cmdline.append('--python-version={}'.format('.'.join(map(str, version))))
 
+        program_text = '\n'.join(testcase.input)
+        flags = re.search('# flags: (.*)$', program_text, flags=re.MULTILINE)
+        if flags:
+            flag_list = flags.group(1).split()
+            mypy_cmdline.extend(flag_list)
+
         # Write the program to a file.
         program_path = os.path.join(test_temp_dir, 'main.py')
         mypy_cmdline.append(program_path)