Use pytest Node.from_parent if available (#9263)

* Use pytest Node.from_parent if available

* Use pytest Node.from_parent unconditionally (requires pytest 5.4+)

* Bump pytest test requirements

* Require pytest 6.0 and remove unused type ignores

* Make flake8 happy

Author: llchan

mypy/test/data.py

@@ -9,7 +9,7 @@
 from abc import abstractmethod
 import sys
 
-import pytest  # type: ignore  # no pytest in typeshed
+import pytest
 from typing import List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
 
 from mypy.test.config import test_data_prefix, test_temp_dir, PREFIX
@@ -160,9 +160,12 @@ def parse_test_case(case: 'DataDrivenTestCase') -> None:
     case.expected_fine_grained_targets = targets
 
 
-class DataDrivenTestCase(pytest.Item):  # type: ignore  # inheriting from Any
+class DataDrivenTestCase(pytest.Item):
     """Holds parsed data-driven test cases, and handles directory setup and teardown."""
 
+    # Override parent member type
+    parent = None  # type: DataSuiteCollector
+
     input = None  # type: List[str]
     output = None  # type: List[str]  # Output for the first pass
     output2 = None  # type: Dict[int, List[str]]  # Output for runs 2+, indexed by run number
@@ -266,7 +269,7 @@ def repr_failure(self, excinfo: Any, style: Optional[Any] = None) -> str:
             # call exit() and they already print out a stack trace.
             excrepr = excinfo.exconly()
         else:
-            self.parent._prunetraceback(excinfo)
+            self.parent._prunetraceback(excinfo)  # type: ignore[no-untyped-call]
             excrepr = excinfo.getrepr(style='short')
 
         return "data: {}:{}:\n{}".format(self.file, self.line, excrepr)
@@ -510,7 +513,9 @@ def pytest_pycollect_makeitem(collector: Any, name: str,
             # Non-None result means this obj is a test case.
             # The collect method of the returned DataSuiteCollector instance will be called later,
             # with self.obj being obj.
-            return DataSuiteCollector(name, parent=collector)
+            return DataSuiteCollector.from_parent(  # type: ignore[no-untyped-call]
+                parent=collector, name=name
+            )
     return None
 
 
@@ -535,19 +540,23 @@ def split_test_cases(parent: 'DataSuiteCollector', suite: 'DataSuite',
     for i in range(1, len(cases), 6):
         name, writescache, only_when, platform_flag, skip, data = cases[i:i + 6]
         platform = platform_flag[1:] if platform_flag else None
-        yield DataDrivenTestCase(parent, suite, file,
-                                 name=add_test_name_suffix(name, suite.test_name_suffix),
-                                 writescache=bool(writescache),
-                                 only_when=only_when,
-                                 platform=platform,
-                                 skip=bool(skip),
-                                 data=data,
-                                 line=line_no)
+        yield DataDrivenTestCase.from_parent(
+            parent=parent,
+            suite=suite,
+            file=file,
+            name=add_test_name_suffix(name, suite.test_name_suffix),
+            writescache=bool(writescache),
+            only_when=only_when,
+            platform=platform,
+            skip=bool(skip),
+            data=data,
+            line=line_no,
+        )
         line_no += data.count('\n') + 1
 
 
-class DataSuiteCollector(pytest.Class):  # type: ignore  # inheriting from Any
-    def collect(self) -> Iterator[pytest.Item]:  # type: ignore
+class DataSuiteCollector(pytest.Class):
+    def collect(self) -> Iterator[pytest.Item]:
         """Called by pytest on each of the object returned from pytest_pycollect_makeitem"""
 
         # obj is the object for which pytest_pycollect_makeitem returned self.

mypy/test/helpers.py

@@ -10,7 +10,7 @@
 from mypy import defaults
 import mypy.api as api
 
-import pytest  # type: ignore  # no pytest in typeshed
+import pytest
 
 # Exporting Suite as alias to TestCase for backwards compatibility
 # TODO: avoid aliasing - import and subclass TestCase directly

mypy/test/testfinegrained.py

@@ -35,7 +35,7 @@
 from mypy.config_parser import parse_config_file
 from mypy.find_sources import create_source_list
 
-import pytest  # type: ignore  # no pytest in typeshed
+import pytest
 
 # Set to True to perform (somewhat expensive) checks for duplicate AST nodes after merge
 CHECK_CONSISTENCY = False

mypy/test/testipc.py

@@ -3,7 +3,7 @@
 
 from mypy.ipc import IPCClient, IPCServer
 
-import pytest  # type: ignore
+import pytest
 import sys
 import time
 

mypy/test/testparse.py

@@ -2,7 +2,7 @@
 
 import sys
 
-from pytest import skip  # type: ignore[import]
+from pytest import skip
 
 from mypy import defaults
 from mypy.test.helpers import assert_string_arrays_equal, parse_options

mypy/test/testpep561.py

@@ -1,6 +1,6 @@
 from contextlib import contextmanager
 import os
-import pytest  # type: ignore
+import pytest
 import re
 import subprocess
 from subprocess import PIPE

mypy/test/testpythoneval.py

@@ -18,7 +18,7 @@
 import sys
 from tempfile import TemporaryDirectory
 
-import pytest  # type: ignore  # no pytest in typeshed
+import pytest
 
 from typing import List
 

mypyc/test/testutil.py

@@ -7,7 +7,7 @@
 import shutil
 from typing import List, Callable, Iterator, Optional, Tuple
 
-import pytest  # type: ignore[import]
+import pytest
 
 from mypy import build
 from mypy.errors import CompileError

pytest.ini

@@ -1,6 +1,5 @@
 [pytest]
-# testpaths is new in 2.8
-minversion = 2.8
+minversion = 6.0.0
 
 testpaths = mypy/test mypyc/test
 

test-requirements.txt

@@ -5,11 +5,10 @@ flake8-bugbear; python_version >= '3.5'
 flake8-pyi>=20.5; python_version >= '3.6'
 lxml>=4.4.0
 psutil>=4.0
-pytest==5.3.2
-pytest-xdist>=1.22
-# pytest-xdist depends on pytest-forked and 1.1.0 doesn't install clean on macOS 3.5
-pytest-forked>=1.0.0,<1.1.0
-pytest-cov>=2.4.0
+pytest>=6.0.0,<7.0.0
+pytest-xdist>=1.34.0,<2.0.0
+pytest-forked>=1.3.0,<2.0.0
+pytest-cov>=2.10.0,<3.0.0
 typing>=3.5.2; python_version < '3.5'
 py>=1.5.2
 virtualenv<20