pythongh-124594: Create and reuse the same context for the entire asyncio REPL session (python#124595)

Co-authored-by: Andrew Svetlov <[email protected]>

Author: bswck

Lib/asyncio/__main__.py

@@ -1,6 +1,7 @@
 import ast
 import asyncio
 import concurrent.futures
+import contextvars
 import inspect
 import os
 import site
@@ -22,6 +23,7 @@ def __init__(self, locals, loop):
         self.compile.compiler.flags |= ast.PyCF_ALLOW_TOP_LEVEL_AWAIT
 
         self.loop = loop
+        self.context = contextvars.copy_context()
 
     def runcode(self, code):
         global return_code
@@ -55,12 +57,12 @@ def callback():
                 return
 
             try:
-                repl_future = self.loop.create_task(coro)
+                repl_future = self.loop.create_task(coro, context=self.context)
                 futures._chain_future(repl_future, future)
             except BaseException as exc:
                 future.set_exception(exc)
 
-        loop.call_soon_threadsafe(callback)
+        loop.call_soon_threadsafe(callback, context=self.context)
 
         try:
             return future.result()

Lib/test/test_repl.py

@@ -291,5 +291,42 @@ def f():
         self.assertEqual(traceback_lines, expected_lines)
 
 
+class TestAsyncioREPLContextVars(unittest.TestCase):
+    def test_toplevel_contextvars_sync(self):
+        user_input = dedent("""\
+        from contextvars import ContextVar
+        var = ContextVar("var", default="failed")
+        var.set("ok")
+        """)
+        p = spawn_repl("-m", "asyncio")
+        p.stdin.write(user_input)
+        user_input2 = dedent("""
+        print(f"toplevel contextvar test: {var.get()}")
+        """)
+        p.stdin.write(user_input2)
+        output = kill_python(p)
+        self.assertEqual(p.returncode, 0)
+        expected = "toplevel contextvar test: ok"
+        self.assertIn(expected, output, expected)
+
+    def test_toplevel_contextvars_async(self):
+        user_input = dedent("""\
+        from contextvars import ContextVar
+        var = ContextVar('var', default='failed')
+        """)
+        p = spawn_repl("-m", "asyncio")
+        p.stdin.write(user_input)
+        user_input2 = "async def set_var(): var.set('ok')\n"
+        p.stdin.write(user_input2)
+        user_input3 = "await set_var()\n"
+        p.stdin.write(user_input3)
+        user_input4 = "print(f'toplevel contextvar test: {var.get()}')\n"
+        p.stdin.write(user_input4)
+        output = kill_python(p)
+        self.assertEqual(p.returncode, 0)
+        expected = "toplevel contextvar test: ok"
+        self.assertIn(expected, output, expected)
+
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2024-09-26-13-43-39.gh-issue-124594.peYhsP.rst

@@ -0,0 +1 @@
+All :mod:`asyncio` REPL prompts run in the same :class:`context <contextvars.Context>`. Contributed by Bartosz Sławecki.