Support all Popen arguments up to Python 3.10

Fixes #53.

3 files changed, 71 insertions, 17 deletions

diff --git a/NEWS b/NEWS
index af2c00c..1439d53 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ NEXT
 
 * Dropped support for Python 2.7, Python 3.4 and Python 3.5 (EOL).
 * Added support for Python 3.7-3.10.
+* Support all ``subprocess.Popen`` arguments up to Python 3.10.
 
 3.0.0
 ~~~~~
diff --git a/fixtures/_fixtures/popen.py b/fixtures/_fixtures/popen.py
index c35ed5e..ffa9bf4 100644
--- a/fixtures/_fixtures/popen.py
+++ b/fixtures/_fixtures/popen.py
@@ -20,6 +20,7 @@ __all__ = [
 
 import random
 import subprocess
+import sys
 
 from fixtures import Fixture
 
@@ -126,13 +127,38 @@ class FakePopen(Fixture):
         stdin=_unpassed, stdout=_unpassed, stderr=_unpassed,
         preexec_fn=_unpassed, close_fds=_unpassed, shell=_unpassed,
         cwd=_unpassed, env=_unpassed, universal_newlines=_unpassed,
-        startupinfo=_unpassed, creationflags=_unpassed):
+        startupinfo=_unpassed, creationflags=_unpassed,
+        restore_signals=_unpassed, start_new_session=_unpassed,
+        pass_fds=_unpassed, *, group=_unpassed, extra_groups=_unpassed,
+        user=_unpassed, umask=_unpassed, encoding=_unpassed,
+        errors=_unpassed, text=_unpassed, pipesize=_unpassed):
+        # Reject arguments introduced by newer versions of Python in older
+        # versions; this makes it harder to accidentally hide compatibility
+        # problems using test doubles.
+        if sys.version_info < (3, 7) and text is not FakePopen._unpassed:
+            raise TypeError(
+                "FakePopen.__call__() got an unexpected keyword argument "
+                "'text'")
+        if sys.version_info < (3, 9):
+            for arg_name in "group", "extra_groups", "user", "umask":
+                if locals()[arg_name] is not FakePopen._unpassed:
+                    raise TypeError(
+                        "FakePopen.__call__() got an unexpected keyword "
+                        "argument '{}'".format(arg_name))
+        if sys.version_info < (3, 10) and pipesize is not FakePopen._unpassed:
+            raise TypeError(
+                "FakePopen.__call__() got an unexpected keyword argument "
+                "'pipesize'")
+
         proc_args = dict(args=args)
         local = locals()
         for param in [
             "bufsize", "executable", "stdin", "stdout", "stderr",
             "preexec_fn", "close_fds", "shell", "cwd", "env",
-            "universal_newlines", "startupinfo", "creationflags"]:
+            "universal_newlines", "startupinfo", "creationflags",
+            "restore_signals", "start_new_session", "pass_fds", "group",
+            "extra_groups", "user", "umask", "encoding", "errors", "text",
+            "pipesize"]:
             if local[param] is not FakePopen._unpassed:
                 proc_args[param] = local[param]
         proc_info = self.get_info(proc_args)
diff --git a/fixtures/tests/_fixtures/test_popen.py b/fixtures/tests/_fixtures/test_popen.py
index c5dc141..cafd98e 100644
--- a/fixtures/tests/_fixtures/test_popen.py
+++ b/fixtures/tests/_fixtures/test_popen.py
@@ -15,6 +15,7 @@
 
 import io
 import subprocess
+import sys
 
 import testtools
 
@@ -48,33 +49,59 @@ class TestFakePopen(testtools.TestCase, TestWithFixtures):
         proc = fixture(['foo'])
         self.assertEqual('stdout', proc.stdout)
 
-    def test_handles_all_2_7_args(self):
-        all_args = dict(
-            args="args", bufsize="bufsize", executable="executable",
-            stdin="stdin", stdout="stdout", stderr="stderr",
-            preexec_fn="preexec_fn", close_fds="close_fds", shell="shell",
-            cwd="cwd", env="env", universal_newlines="universal_newlines",
-            startupinfo="startupinfo", creationflags="creationflags")
-        def get_info(proc_args):
-            self.assertEqual(all_args, proc_args)
-            return {}
-        fixture = self.useFixture(FakePopen(get_info))
-        fixture(**all_args)
-
-    def test_handles_all_3_7_args(self):
+    def test_handles_all_Popen_args(self):
         all_args = dict(
             args="args", bufsize="bufsize", executable="executable",
             stdin="stdin", stdout="stdout", stderr="stderr",
             preexec_fn="preexec_fn", close_fds="close_fds", shell="shell",
             cwd="cwd", env="env", universal_newlines="universal_newlines",
             startupinfo="startupinfo", creationflags="creationflags",
-            text="text")
+            restore_signals="restore_signals",
+            start_new_session="start_new_session", pass_fds="pass_fds",
+            encoding="encoding", errors="errors")
+        if sys.version_info >= (3, 7):
+            all_args["text"] = "text"
+        if sys.version_info >= (3, 9):
+            all_args["group"] = "group"
+            all_args["extra_groups"] = "extra_groups"
+            all_args["user"] = "user"
+            all_args["umask"] = "umask"
+        if sys.version_info >= (3, 10):
+            all_args["pipesize"] = "pipesize"
         def get_info(proc_args):
             self.assertEqual(all_args, proc_args)
             return {}
         fixture = self.useFixture(FakePopen(get_info))
         fixture(**all_args)
 
+    @testtools.skipUnless(
+        sys.version_info < (3, 7), "only relevant on Python <3.7")
+    def test_rejects_3_7_args_on_older_versions(self):
+        fixture = self.useFixture(FakePopen(lambda proc_args: {}))
+        with testtools.ExpectedException(
+                TypeError, r".* got an unexpected keyword argument 'text'"):
+            fixture(args="args", text=True)
+
+    @testtools.skipUnless(
+        sys.version_info < (3, 9), "only relevant on Python <3.9")
+    def test_rejects_3_9_args_on_older_versions(self):
+        fixture = self.useFixture(FakePopen(lambda proc_args: {}))
+        for arg_name in ("group", "extra_groups", "user", "umask"):
+            kwargs = {arg_name: arg_name}
+            expected_message = (
+                r".* got an unexpected keyword argument '{}'".format(arg_name))
+            with testtools.ExpectedException(TypeError, expected_message):
+                fixture(args="args", **kwargs)
+
+    @testtools.skipUnless(
+        sys.version_info < (3, 10), "only relevant on Python <3.10")
+    def test_rejects_3_10_args_on_older_versions(self):
+        fixture = self.useFixture(FakePopen(lambda proc_args: {}))
+        with testtools.ExpectedException(
+                TypeError,
+                r".* got an unexpected keyword argument 'pipesize'"):
+            fixture(args="args", pipesize=1024)
+
     def test_custom_returncode(self):
         def get_info(proc_args):
             return dict(returncode=1)