BUG: Fix mypy error

Define ip only if we're type checking.

IPython/core/tests/test_async_helpers.py

@@ -1,316 +1,322 b''
 """
-Test for async helpers. 
+Test for async helpers.
 
 Should only trigger on python 3.5+ or will have syntax errors.
 """
 from itertools import chain, repeat
 import nose.tools as nt
 from textwrap import dedent, indent
 from unittest import TestCase
 from IPython.testing.decorators import skip_without
 import sys
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from IPython import get_ipython
+    ip = get_ipython()
+
 
 iprc = lambda x: ip.run_cell(dedent(x)).raise_error()
 iprc_nr = lambda x: ip.run_cell(dedent(x))
 
 from IPython.core.async_helpers import _should_be_async
 
 class AsyncTest(TestCase):
     def test_should_be_async(self):
         nt.assert_false(_should_be_async("False"))
         nt.assert_true(_should_be_async("await bar()"))
         nt.assert_true(_should_be_async("x = await bar()"))
         nt.assert_false(
             _should_be_async(
                 dedent(
                     """
             async def awaitable():
                 pass
         """
                 )
             )
         )
 
     def _get_top_level_cases(self):
         # These are test cases that should be valid in a function
         # but invalid outside of a function.
         test_cases = []
         test_cases.append(('basic', "{val}"))
 
         # Note, in all conditional cases, I use True instead of
         # False so that the peephole optimizer won't optimize away
         # the return, so CPython will see this as a syntax error:
         #
         # while True:
         #    break
         #    return
         #
         # But not this:
         #
         # while False:
         #    return
         #
         # See https://bugs.python.org/issue1875
 
         test_cases.append(('if', dedent("""
         if True:
             {val}
         """)))
 
         test_cases.append(('while', dedent("""
         while True:
             {val}
             break
         """)))
 
         test_cases.append(('try', dedent("""
         try:
             {val}
         except:
             pass
         """)))
 
         test_cases.append(('except', dedent("""
         try:
             pass
         except:
             {val}
         """)))
 
         test_cases.append(('finally', dedent("""
         try:
             pass
         except:
             pass
         finally:
             {val}
         """)))
 
         test_cases.append(('for', dedent("""
         for _ in range(4):
             {val}
         """)))
 
 
         test_cases.append(('nested', dedent("""
         if True:
             while True:
                 {val}
                 break
         """)))
 
         test_cases.append(('deep-nested', dedent("""
         if True:
             while True:
                 break
                 for x in range(3):
                     if True:
                         while True:
                             for x in range(3):
                                 {val}
         """)))
 
         return test_cases
 
     def _get_ry_syntax_errors(self):
         # This is a mix of tests that should be a syntax error if
         # return or yield whether or not they are in a function
 
         test_cases = []
 
         test_cases.append(('class', dedent("""
         class V:
             {val}
         """)))
 
         test_cases.append(('nested-class', dedent("""
         class V:
             class C:
                 {val}
         """)))
 
         return test_cases
 
 
     def test_top_level_return_error(self):
         tl_err_test_cases = self._get_top_level_cases()
         tl_err_test_cases.extend(self._get_ry_syntax_errors())
 
         vals = ('return', 'yield', 'yield from (_ for _ in range(3))',
                 dedent('''
                     def f():
                         pass
                     return
                     '''),
                 )
 
         for test_name, test_case in tl_err_test_cases:
             # This example should work if 'pass' is used as the value
             with self.subTest((test_name, 'pass')):
                 iprc(test_case.format(val='pass'))
 
             # It should fail with all the values
             for val in vals:
                 with self.subTest((test_name, val)):
                     msg = "Syntax error not raised for %s, %s" % (test_name, val)
                     with self.assertRaises(SyntaxError, msg=msg):
                         iprc(test_case.format(val=val))
 
     def test_in_func_no_error(self):
         # Test that the implementation of top-level return/yield
         # detection isn't *too* aggressive, and works inside a function
         func_contexts = []
 
         func_contexts.append(('func', False, dedent("""
         def f():""")))
 
         func_contexts.append(('method', False, dedent("""
         class MyClass:
             def __init__(self):
         """)))
 
         func_contexts.append(('async-func', True,  dedent("""
         async def f():""")))
 
         func_contexts.append(('async-method', True,  dedent("""
         class MyClass:
             async def f(self):""")))
 
         func_contexts.append(('closure', False, dedent("""
         def f():
             def g():
         """)))
 
         def nest_case(context, case):
             # Detect indentation
             lines = context.strip().splitlines()
             prefix_len = 0
             for c in lines[-1]:
                 if c != ' ':
                     break
                 prefix_len += 1
 
             indented_case = indent(case, ' ' * (prefix_len + 4))
             return context + '\n' + indented_case
 
         # Gather and run the tests
 
         # yield is allowed in async functions, starting in Python 3.6,
         # and yield from is not allowed in any version
         vals = ('return', 'yield', 'yield from (_ for _ in range(3))')
         async_safe = (True,
                         True,
                         False)
         vals = tuple(zip(vals, async_safe))
 
         success_tests = zip(self._get_top_level_cases(), repeat(False))
         failure_tests = zip(self._get_ry_syntax_errors(), repeat(True))
 
         tests = chain(success_tests, failure_tests)
 
         for context_name, async_func, context in func_contexts:
             for (test_name, test_case), should_fail in tests:
                 nested_case = nest_case(context, test_case)
 
                 for val, async_safe in vals:
                     val_should_fail = (should_fail or
                                         (async_func and not async_safe))
 
                     test_id = (context_name, test_name, val)
                     cell = nested_case.format(val=val)
 
                     with self.subTest(test_id):
                         if val_should_fail:
                             msg = ("SyntaxError not raised for %s" %
                                     str(test_id))
                             with self.assertRaises(SyntaxError, msg=msg):
                                 iprc(cell)
 
                                 print(cell)
                         else:
                             iprc(cell)
 
     def test_nonlocal(self):
         # fails if outer scope is not a function scope or if var not defined
         with self.assertRaises(SyntaxError):
             iprc("nonlocal x")
             iprc("""
             x = 1
             def f():
                 nonlocal x
                 x = 10000
                 yield x
             """)
             iprc("""
             def f():
                 def g():
                     nonlocal x
                     x = 10000
                     yield x
             """)
 
         # works if outer scope is a function scope and var exists
         iprc("""
         def f():
             x = 20
             def g():
                 nonlocal x
                 x = 10000
                 yield x
         """)
 
 
     def test_execute(self):
         iprc("""
         import asyncio
         await asyncio.sleep(0.001)
         """
         )
 
     def test_autoawait(self):
         iprc("%autoawait False")
         iprc("%autoawait True")
         iprc("""
         from asyncio import sleep
         await sleep(0.1)
         """
         )
-    
+
     if sys.version_info < (3,9):
         # new pgen parser in 3.9 does not raise MemoryError on too many nested
         # parens anymore
         def test_memory_error(self):
             with self.assertRaises(MemoryError):
                 iprc("(" * 200 + ")" * 200)
 
     @skip_without('curio')
     def test_autoawait_curio(self):
         iprc("%autoawait curio")
 
     @skip_without('trio')
     def test_autoawait_trio(self):
         iprc("%autoawait trio")
 
     @skip_without('trio')
     def test_autoawait_trio_wrong_sleep(self):
         iprc("%autoawait trio")
         res = iprc_nr("""
         import asyncio
         await asyncio.sleep(0)
         """)
         with nt.assert_raises(TypeError):
             res.raise_error()
 
     @skip_without('trio')
     def test_autoawait_asyncio_wrong_sleep(self):
         iprc("%autoawait asyncio")
         res = iprc_nr("""
         import trio
         await trio.sleep(0)
         """)
         with nt.assert_raises(RuntimeError):
             res.raise_error()
 
 
     def tearDown(self):
         ip.loop_runner = "asyncio"