Initial pass at timeout for subprocessing pytest

pytest-dev/pytest#4073

setup.py

@@ -65,6 +65,7 @@ def main():
         "attrs>=17.4.0",
         "more-itertools>=4.0.0",
         "atomicwrites>=1.0",
+        "monotonic",
     ]
     # if _PYTEST_SETUP_SKIP_PLUGGY_DEP is set, skip installing pluggy;
     # used by tox.ini to test with pluggy master

src/_pytest/pytester.py

@@ -3,6 +3,7 @@ from __future__ import absolute_import, division, print_function
 
 import codecs
 import gc
+import monotonic
 import os
 import platform
 import re
@@ -482,6 +483,9 @@ class Testdir(object):
 
     """
 
+    class TimeoutExpired(Exception):
+        pass
+
     def __init__(self, request, tmpdir_factory):
         self.request = request
         self._mod_collections = WeakKeyDictionary()
@@ -1039,7 +1043,7 @@ class Testdir(object):
 
         return popen
 
-    def run(self, *cmdargs):
+    def run(self, *cmdargs, **kwargs):
         """Run a command with arguments.
 
         Run a process using subprocess.Popen saving the stdout and stderr.
@@ -1061,7 +1065,27 @@ class Testdir(object):
             popen = self.popen(
                 cmdargs, stdout=f1, stderr=f2, close_fds=(sys.platform != "win32")
             )
-            ret = popen.wait()
+            timeout = kwargs.get('timeout')
+            if timeout is None:
+                ret = popen.wait()
+            elif six.PY3:
+                try:
+                    ret = popen.wait(timeout)
+                except subprocess.TimeoutExpired:
+                    raise self.TimeoutExpired
+            else:
+                end = monotonic.monotonic() + timeout
+
+                while True:
+                    ret = popen.poll()
+                    if ret is not None:
+                        break
+
+                    remaining = end - monotonic.monotonic()
+                    if remaining <= 0:
+                        raise self.TimeoutExpired()
+
+                    time.sleep(remaining * 0.9)
         finally:
             f1.close()
             f2.close()
@@ -1119,7 +1143,13 @@ class Testdir(object):
         if plugins:
             args = ("-p", plugins[0]) + args
         args = self._getpytestargs() + args
-        return self.run(*args)
+
+        if "timeout" in kwargs:
+            timeout = {"timeout": kwargs["timeout"]}
+        else:
+            timeout = {}
+
+        return self.run(*args, **timeout)
 
     def spawn_pytest(self, string, expect_timeout=10.0):
         """Run pytest using pexpect.

testing/test_pytester.py

@@ -3,6 +3,7 @@ from __future__ import absolute_import, division, print_function
 import os
 import py.path
 import pytest
+import subprocess
 import sys
 import _pytest.pytester as pytester
 from _pytest.pytester import HookRecorder
@@ -401,3 +402,20 @@ def test_testdir_subprocess(testdir):
 def test_unicode_args(testdir):
     result = testdir.runpytest("-k", u"💩")
     assert result.ret == EXIT_NOTESTSCOLLECTED
+
+
+def test_testdir_run_no_timeout(testdir):
+    testfile = testdir.makepyfile("def test_no_timeout(): pass")
+    assert testdir.runpytest_subprocess(testfile).ret == EXIT_OK
+
+
+def test_testdir_run_timeout_expires(testdir):
+    testfile = testdir.makepyfile(
+        """
+        import time
+        
+        def test_timeout():
+            time.sleep(10)"""
+    )
+    with pytest.raises(testdir.TimeoutExpired):
+        testdir.runpytest_subprocess(testfile, timeout=0.5)