bpo-30696: Fix the REPL looping endlessly when no memory (GH-4160)

1 files changed, 62 insertions, 0 deletions

diff --git a/Lib/test/test_repl.py b/Lib/test/test_repl.py
new file mode 100644
index 0000000..9efd459
--- /dev/null
+++ b/Lib/test/test_repl.py
@@ -0,0 +1,62 @@
+"""Test the interactive interpreter."""
+
+import sys
+import os
+import unittest
+import subprocess
+from textwrap import dedent
+from test.support import cpython_only, SuppressCrashReport
+from test.support.script_helper import kill_python
+
+def spawn_repl(*args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, **kw):
+    """Run the Python REPL with the given arguments.
+
+    kw is extra keyword args to pass to subprocess.Popen. Returns a Popen
+    object.
+    """
+
+    # To run the REPL without using a terminal, spawn python with the command
+    # line option '-i' and the process name set to '<stdin>'.
+    # The directory of argv[0] must match the directory of the Python
+    # executable for the Popen() call to python to succeed as the directory
+    # path may be used by Py_GetPath() to build the default module search
+    # path.
+    stdin_fname = os.path.join(os.path.dirname(sys.executable), "<stdin>")
+    cmd_line = [stdin_fname, '-E', '-i']
+    cmd_line.extend(args)
+
+    # Set TERM=vt100, for the rationale see the comments in spawn_python() of
+    # test.support.script_helper.
+    env = kw.setdefault('env', dict(os.environ))
+    env['TERM'] = 'vt100'
+    return subprocess.Popen(cmd_line, executable=sys.executable,
+                            stdin=subprocess.PIPE,
+                            stdout=stdout, stderr=stderr,
+                            **kw)
+
+class TestInteractiveInterpreter(unittest.TestCase):
+
+    @cpython_only
+    def test_no_memory(self):
+        # Issue #30696: Fix the interactive interpreter looping endlessly when
+        # no memory. Check also that the fix does not break the interactive
+        # loop when an exception is raised.
+        user_input = """
+            import sys, _testcapi
+            1/0
+            print('After the exception.')
+            _testcapi.set_nomemory(0)
+            sys.exit(0)
+        """
+        user_input = dedent(user_input)
+        user_input = user_input.encode()
+        p = spawn_repl()
+        with SuppressCrashReport():
+            p.stdin.write(user_input)
+        output = kill_python(p)
+        self.assertIn(b'After the exception.', output)
+        # Exit code 120: Py_FinalizeEx() failed to flush stdout and stderr.
+        self.assertIn(p.returncode, (1, 120))
+
+if __name__ == "__main__":
+    unittest.main()