Make it work on Windows

pytest_mypy/collect.py

@@ -1,3 +1,4 @@
+import tempfile
 from typing import Any, Dict, List
 
 import pytest
@@ -96,7 +97,7 @@ def pytest_collect_file(path, parent):
 
 def pytest_addoption(parser: Parser) -> None:
     group = parser.getgroup('mypy-tests')
-    group.addoption('--mypy-testing-base', type=str, default='/tmp',
+    group.addoption('--mypy-testing-base', type=str, default=tempfile.gettempdir(),
                     help='Base directory for tests to use')
     group.addoption('--mypy-ini-file', type=str,
                     help='Which .ini file to use as a default config for tests')

pytest_mypy/item.py

@@ -7,7 +7,6 @@
 from pathlib import Path
 from typing import Any, Dict, List, Tuple, Callable, Optional
 
-import capturer
 import pytest
 from _pytest._code import ExceptionInfo
 from _pytest._code.code import ReprEntry, ReprFileLocation
@@ -17,7 +16,12 @@
 from mypy.main import process_options
 from pytest_mypy import utils
 from pytest_mypy.collect import File, YamlTestFile
-from pytest_mypy.utils import TypecheckAssertionError, assert_string_arrays_equal, fname_to_module
+from pytest_mypy.utils import (
+    TypecheckAssertionError,
+    capture_std_streams,
+    assert_string_arrays_equal,
+    fname_to_module,
+)
 
 
 class TraceLastReprEntry(ReprEntry):
@@ -163,6 +167,9 @@ def typecheck_in_new_subprocess(self, execution_path: Path, mypy_cmd_options: Li
 
         # add current directory to path
         self.environment_variables['PYTHONPATH'] = str(execution_path)
+        # Windows requires this to be set, otherwise the interpreter crashes
+        if 'SYSTEMROOT' in os.environ:
+            self.environment_variables['SYSTEMROOT'] = os.environ['SYSTEMROOT']
         completed = subprocess.run([mypy_executable, *mypy_cmd_options],
                                    stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                    cwd=os.getcwd(),
@@ -180,12 +187,10 @@ def typecheck_in_same_process(self, execution_path: Path, mypy_cmd_options: List
                 # add current directory to path
                 sys.path.insert(0, str(execution_path))
 
-                with capturer.CaptureOutput(merged=False) as captured_std_streams:
+                with capture_std_streams() as (stdout, stderr):
                     return_code = run_mypy_typechecking(mypy_cmd_options)
 
-                stdout = captured_std_streams.stdout.get_text()
-                stderr = captured_std_streams.stderr.get_text()
-                return return_code, (stdout, stderr)
+                return return_code, (stdout.getvalue(), stderr.getvalue())
 
     def execute_extension_hook(self) -> None:
         extension_hook_fqname = self.config.option.mypy_extension_hook

pytest_mypy/tests/test-extension.yml

@@ -3,5 +3,5 @@
         # if hook works, main should contain 'reveal_type(1)'
     reveal_type: 1
     out: |
-        main:1: note: Revealed type is 'builtins.int'
+        main:1: note: Revealed type is 'Literal[1]?'
 

pytest_mypy/utils.py

@@ -1,11 +1,13 @@
 # Borrowed from Pew.
 # See https://github.com/berdario/pew/blob/master/pew/_utils.py#L82
+import contextlib
 import inspect
+import io
 import os
 import re
 import sys
 from pathlib import Path
-from typing import Callable, List, Optional, Tuple
+from typing import Callable, Iterator, List, Optional, Tuple
 
 from decorator import contextmanager
 
@@ -310,3 +312,15 @@ def cd(path):
         yield
     finally:
         os.chdir(prev_cwd)
+
+
+@contextmanager
+def capture_std_streams() -> Iterator[Tuple[io.StringIO, io.StringIO]]:
+    """Context manager to temporarily capture stdout and stderr.
+
+    Returns ``(stdout, stderr)``.
+    """
+    out = io.StringIO()
+    err = io.StringIO()
+    with contextlib.redirect_stdout(out), contextlib.redirect_stderr(err):
+        yield out, err

setup.py

@@ -7,7 +7,6 @@
     'pytest',
     'mypy>=0.730',
     'decorator',
-    'capturer',
     'pyyaml'
 ]