Run tests with tty (fixes #869)

sebastinas · sebastinas · commit b333f2811184 · 2021-01-24T22:23:28.000+01:00
diff --git a/bpython/test/test_args.py b/bpython/test/test_args.py
@@ -1,14 +1,67 @@
+import errno
+import os
+import pty
 import re
+import select
 import subprocess
 import sys
 import tempfile
 import unittest
 
 from textwrap import dedent
 from bpython import args
+from bpython.config import getpreferredencoding
 from bpython.test import FixLanguageTestCase as TestCase
 
 
+def run_with_tty(command):
+    # based on https://stackoverflow.com/questions/52954248/capture-output-as-a-tty-in-python
+    master_stdout, slave_stdout = pty.openpty()
+    master_stderr, slave_stderr = pty.openpty()
+    master_stdin, slave_stdin = pty.openpty()
+
+    p = subprocess.Popen(
+        command,
+        stdout=slave_stdout,
+        stderr=slave_stderr,
+        stdin=slave_stdin,
+        close_fds=True,
+    )
+    for fd in (slave_stdout, slave_stderr, slave_stdin):
+        os.close(fd)
+
+    readable = [master_stdout, master_stderr]
+    result = {master_stdout: b"", master_stderr: b""}
+    try:
+        while readable:
+            ready, _, _ = select.select(readable, [], [], 1)
+            for fd in ready:
+                try:
+                    data = os.read(fd, 512)
+                except OSError as e:
+                    if e.errno != errno.EIO:
+                        raise
+                    # EIO means EOF on some systems
+                    readable.remove(fd)
+                else:
+                    if not data:  # EOF
+                        readable.remove(fd)
+                    result[fd] += data
+    finally:
+        for fd in (master_stdout, master_stderr, master_stdin):
+            os.close(fd)
+        if p.poll() is None:
+            p.kill()
+        p.wait()
+        if p.returncode:
+            raise RuntimeError(f"Subprocess exited with {p.returncode}")
+
+    return (
+        result[master_stdout].decode(getpreferredencoding()),
+        result[master_stderr].decode(getpreferredencoding()),
+    )
+
+
 class TestExecArgs(unittest.TestCase):
     # These tests are currently not very useful. Under pytest neither stdout nor stdin are ttys,
     # hence bpython.args.parse will just exectute code by falling back to Python.
@@ -24,13 +77,9 @@ def test_exec_dunder_file(self):
                 )
             )
             f.flush()
-            p = subprocess.Popen(
-                [sys.executable] + ["-m", "bpython.curtsies", f.name],
-                stderr=subprocess.PIPE,
-                universal_newlines=True,
+            _, stderr = run_with_tty(
+                [sys.executable] + ["-m", "bpython.curtsies", f.name]
             )
-            (_, stderr) = p.communicate()
-
             self.assertEqual(stderr.strip(), f.name)
 
     def test_exec_nonascii_file(self):
@@ -44,33 +93,25 @@ def test_exec_nonascii_file(self):
                 )
             )
             f.flush()
-            try:
-                subprocess.check_call(
-                    [sys.executable, "-m", "bpython.curtsies", f.name]
-                )
-            except subprocess.CalledProcessError:
-                self.fail("Error running module with nonascii characters")
+            _, stderr = run_with_tty(
+                [sys.executable, "-m", "bpython.curtsies", f.name],
+            )
+            self.assertEqual(len(stderr), 0)
 
     def test_exec_nonascii_file_linenums(self):
         with tempfile.NamedTemporaryFile(mode="w") as f:
             f.write(
                 dedent(
                     """\
-                #!/usr/bin/env python
-                # coding: utf-8
                 1/0
                 """
                 )
             )
             f.flush()
-            p = subprocess.Popen(
+            _, stderr = run_with_tty(
                 [sys.executable, "-m", "bpython.curtsies", f.name],
-                stderr=subprocess.PIPE,
-                universal_newlines=True,
             )
-            (_, stderr) = p.communicate()
-
-            self.assertIn("line 3", clean_colors(stderr))
+            self.assertIn("line 1", clean_colors(stderr))
 
 
 def clean_colors(s):
