import doctest
import textwrap
import traceback
import types
import unittest
from test.support import BrokenIter
doctests = """
########### Tests borrowed from or inspired by test_genexps.py ############
Test simple loop with conditional
>>> sum([i*i for i in range(100) if i&1 == 1])
166650
Test simple nesting
>>> [(i,j) for i in range(3) for j in range(4)]
[(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
Test nesting with the inner expression dependent on the outer
>>> [(i,j) for i in range(4) for j in range(i)]
[(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2)]
Test the idiom for temporary variable assignment in comprehensions.
>>> [j*j for i in range(4) for j in [i+1]]
[1, 4, 9, 16]
>>> [j*k for i in range(4) for j in [i+1] for k in [j+1]]
[2, 6, 12, 20]
>>> [j*k for i in range(4) for j, k in [(i+1, i+2)]]
[2, 6, 12, 20]
Not assignment
>>> [i*i for i in [*range(4)]]
[0, 1, 4, 9]
>>> [i*i for i in (*range(4),)]
[0, 1, 4, 9]
Make sure the induction variable is not exposed
>>> i = 20
>>> sum([i*i for i in range(100)])
328350
>>> i
20
Verify that syntax error's are raised for listcomps used as lvalues
>>> [y for y in (1,2)] = 10 # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
SyntaxError: ...
>>> [y for y in (1,2)] += 10 # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
SyntaxError: ...
########### Tests borrowed from or inspired by test_generators.py ############
Make a nested list comprehension that acts like range()
>>> def frange(n):
... return [i for i in range(n)]
>>> frange(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Same again, only as a lambda expression instead of a function definition
>>> lrange = lambda n: [i for i in range(n)]
>>> lrange(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Generators can call other generators:
>>> def grange(n):
... for x in [i for i in range(n)]:
... yield x
>>> list(grange(5))
[0, 1, 2, 3, 4]
Make sure that None is a valid return value
>>> [None for i in range(10)]
[None, None, None, None, None, None, None, None, None, None]
"""
class ListComprehensionTest(unittest.TestCase):
def _check_in_scopes(self, code, outputs=None, ns=None, scopes=None, raises=(),
exec_func=exec):
code = textwrap.dedent(code)
scopes = scopes or ["module", "class", "function"]
for scope in scopes:
with self.subTest(scope=scope):
if scope == "class":
newcode = textwrap.dedent("""
class _C:
{code}
""").format(code=textwrap.indent(code, " "))
def get_output(moddict, name):
return getattr(moddict["_C"], name)
elif scope == "function":
newcode = textwrap.dedent("""
def _f():
{code}
return locals()
_out = _f()
""").format(code=textwrap.indent(code, " "))
def get_output(moddict, name):
return moddict["_out"][name]
else:
newcode = code
def get_output(moddict, name):
return moddict[name]
newns = ns.copy() if ns else {}
try:
exec_func(newcode, newns)
except raises as e:
# We care about e.g. NameError vs UnboundLocalError
self.assertIs(type(e), raises)
else:
for k, v in (outputs or {}).items():
self.assertEqual(get_output(newns, k), v, k)
def test_lambdas_with_iteration_var_as_default(self):
code = """
items = [(lambda i=i: i) for i in range(5)]
y = [x() for x in items]
"""
outputs = {"y": [0, 1, 2, 3, 4]}
self._check_in_scopes(code, outputs)
def test_lambdas_with_free_var(self):
code = """
items = [(lambda: i) for i in range(5)]
y = [x() for x in items]
"""
outputs = {"y": [4, 4, 4, 4, 4]}
self._check_in_scopes(code, outputs)
def test_class_scope_free_var_with_class_cell(self):
class C:
def method(self):
super()
return __class__
items = [(lambda: i) for i in range(5)]
y = [x() for x in items]
self.assertEqual(C.y, [4, 4, 4, 4, 4])
self.assertIs(C().method(), C)
def test_references_super(self):
code = """
res = [super for x in [1]]
"""
self._check_in_scopes(code, outputs={"res": [super]})
def test_references___class__(self):
code = """
res = [__class__ for x in [1]]
"""
self._check_in_scopes(code, raises=NameError)
def test_references___class___defined(self):
code = """
__class__ = 2
res = [__class__ for x in [1]]
"""
self._check_in_scopes(
code, outputs={"res": [2]}, scopes=["module", "function"])
self._check_in_scopes(code, raises=NameError, scopes=["class"])
def test_references___class___enclosing(self):
code = """
__class__ = 2
class C:
res = [__class__ for x in [1]]
res = C.res
"""
self._check_in_scopes(code, raises=NameError)
def test_super_and_class_cell_in_sibling_comps(self):
code = """
[super for _ in [1]]
[__class__ for _ in [1]]
"""
self._check_in_scopes(code, raises=NameError)
def test_inner_cell_shadows_outer(self):
code = """
items = [(lambda: i) for i in range(5)]
i = 20
y = [x() for x in items]
"""
outputs = {"y": [4, 4, 4, 4, 4], "i": 20}
self._check_in_scopes(code, outputs)
def test_inner_cell_shadows_outer_no_store(self):
code = """
def f(x):
return [lambda: x for x in range(x)], x
fns, x = f(2)
y = [fn() for fn in fns]
"""
outputs = {"y": [1, 1], "x": 2}
self._check_in_scopes(code, outputs)
def test_closure_can_jump_over_comp_scope(self):
code = """
items = [(lambda: y) for i in range(5)]
y = 2
z = [x() for x in items]
"""
outputs = {"z": [2, 2, 2, 2, 2]}
self._check_in_scopes(code, outputs, scopes=["module", "function"])
def test_cell_inner_free_outer(self):
code = """
def f():
return [lambda: x for x in (x, [1])[1]]
x = ...
y = [fn() for fn in f()]
"""
outputs = {"y": [1]}
self._check_in_scopes(code, outputs, scopes=["module", "function"])
def test_free_inner_cell_outer(self):
code = """
g = 2
def f():
return g
y = [g for x in [1]]
"""
outputs = {"y": [2]}
self._check_in_scopes(code, outputs, scopes=["module", "function"])
self._check_in_scopes(code, scopes=["class"], raises=NameError)
def test_inner_cell_shadows_outer_redefined(self):
code = """
y = 10
items = [(lambda: y) for y in range(5)]
x = y
y = 20
out = [z() for z in items]
"""
outputs = {"x": 10, "out": [4, 4, 4, 4, 4]}
self._check_in_scopes(code, outputs)
def test_shadows_outer_cell(self):
code = """
def inner():
return g
[g for g in range(5)]
x = inner()
"""
outputs = {"x": -1}
self._check_in_scopes(code, outputs, ns={"g": -1})
def test_explicit_global(self):
code = """
global g
x = g
g = 2
items = [g for g in [1]]
y = g
"""
outputs = {"x": 1, "y": 2, "items": [1]}
self._check_in_scopes(code, outputs, ns={"g": 1})
def test_explicit_global_2(self):
code = """
global g
x = g
g = 2
items = [g for x in [1]]
y = g
"""
outputs = {"x": 1, "y": 2, "items": [2]}
self._check_in_scopes(code, outputs, ns={"g": 1})
def test_explicit_global_3(self):
code = """
global g
fns = [lambda: g for g in [2]]
items = [fn() for fn in fns]
"""
outputs = {"items": [2]}
self._check_in_scopes(code, outputs, ns={"g": 1})
def test_assignment_expression(self):
code = """
x = -1
items = [(x:=y) for y in range(3)]
"""
outputs = {"x": 2}
# assignment expression in comprehension is disallowed in class scope
self._check_in_scopes(code, outputs, scopes=["module", "function"])
def test_free_var_in_comp_child(self):
code = """
lst = range(3)
funcs = [lambda: x for x in lst]
inc = [x + 1 for x in lst]
[x for x in inc]
x = funcs[0]()
"""
outputs = {"x": 2}
self._check_in_scopes(code, outputs)
def test_shadow_with_free_and_local(self):
code = """
lst = range(3)
x = -1
funcs = [lambda: x for x in lst]
items = [x + 1 for x in lst]
"""
outputs = {"x": -1}
self._check_in_scopes(code, outputs)
def test_shadow_comp_iterable_name(self):
code = """
x = [1]
y = [x for x in x]
"""
outputs = {"x": [1]}
self._check_in_scopes(code, outputs)
def test_nested_free(self):
code = """
x = 1
def g():
[x for x in range(3)]
return x
g()
"""
outputs = {"x": 1}
self._check_in_scopes(code, outputs, scopes=["module", "function"])
def test_introspecting_frame_locals(self):
code = """
import sys
[i for i in range(2)]
i = 20
sys._getframe().f_locals
"""
outputs = {"i": 20}
self._check_in_scopes(code, outputs)
def test_nested(self):
code = """
l = [2, 3]
y = [[x ** 2 for x in range(x)] for x in l]
"""
outputs = {"y": [[0, 1], [0, 1, 4]]}
self._check_in_scopes(code, outputs)
def test_nested_2(self):
code = """
l = [1, 2, 3]
x = 3
y = [x for [x ** x for x in range(x)][x - 1] in l]
"""
outputs = {"y": [3, 3, 3]}
self._check_in_scopes(code, outputs, scopes=["module", "function"])
self._check_in_scopes(code, scopes=["class"], raises=NameError)
def test_nested_3(self):
code = """
l = [(1, 2), (3, 4), (5, 6)]
y = [x for (x, [x ** x for x in range(x)][x - 1]) in l]
"""
outputs = {"y": [1, 3, 5]}
self._check_in_scopes(code, outputs)
def test_nested_4(self):
code = """
items = [([lambda: x for x in range(2)], lambda: x) for x in range(3)]
out = [([fn() for fn in fns], fn()) for fns, fn in items]
"""
outputs = {"out": [([1, 1], 2), ([1, 1], 2), ([1, 1], 2)]}
self._check_in_scopes(code, outputs)
def test_nameerror(self):
code = """
[x for x in [1]]
x
"""
self._check_in_scopes(code, raises=NameError)
def test_dunder_name(self):
code = """
y = [__x for __x in [1]]
"""
outputs = {"y": [1]}
self._check_in_scopes(code, outputs)
def test_unbound_local_after_comprehension(self):
def f():
if False:
x = 0
[x for x in [1]]
return x
with self.assertRaises(UnboundLocalError):
f()
def test_unbound_local_inside_comprehension(self):
def f():
l = [None]
return [1 for (l[0], l) in [[1, 2]]]
with self.assertRaises(UnboundLocalError):
f()
def test_global_outside_cellvar_inside_plus_freevar(self):
code = """
a = 1
def f():
func, = [(lambda: b) for b in [a]]
return b, func()
x = f()
"""
self._check_in_scopes(
code, {"x": (2, 1)}, ns={"b": 2}, scopes=["function", "module"])
# inside a class, the `a = 1` assignment is not visible
self._check_in_scopes(code, raises=NameError, scopes=["class"])
def test_cell_in_nested_comprehension(self):
code = """
a = 1
def f():
(func, inner_b), = [[lambda: b for b in c] + [b] for c in [[a]]]
return b, inner_b, func()
x = f()
"""
self._check_in_scopes(
code, {"x": (2, 2, 1)}, ns={"b": 2}, scopes=["function", "module"])
# inside a class, the `a = 1` assignment is not visible
self._check_in_scopes(code, raises=NameError, scopes=["class"])
def test_name_error_in_class_scope(self):
code = """
y = 1
[x + y for x in range(2)]
"""
self._check_in_scopes(code, raises=NameError, scopes=["class"])
def test_global_in_class_scope(self):
code = """
y = 2
vals = [(x, y) for x in range(2)]
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, ns={"y": 1}, scopes=["class"])
def test_in_class_scope_inside_function_1(self):
code = """
class C:
y = 2
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, ns={"y": 1}, scopes=["function"])
def test_in_class_scope_inside_function_2(self):
code = """
y = 1
class C:
y = 2
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, scopes=["function"])
def test_in_class_scope_with_global(self):
code = """
y = 1
class C:
global y
y = 2
# Ensure the listcomp uses the global, not the value in the
# class namespace
locals()['y'] = 3
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 2), (1, 2)]}
self._check_in_scopes(code, outputs, scopes=["module", "class"])
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, scopes=["function"])
def test_in_class_scope_with_nonlocal(self):
code = """
y = 1
class C:
nonlocal y
y = 2
# Ensure the listcomp uses the global, not the value in the
# class namespace
locals()['y'] = 3
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 2), (1, 2)]}
self._check_in_scopes(code, outputs, scopes=["function"])
def test_nested_has_free_var(self):
code = """
items = [a for a in [1] if [a for _ in [0]]]
"""
outputs = {"items": [1]}
self._check_in_scopes(code, outputs, scopes=["class"])
def test_nested_free_var_not_bound_in_outer_comp(self):
code = """
z = 1
items = [a for a in [1] if [x for x in [1] if z]]
"""
self._check_in_scopes(code, {"items": [1]}, scopes=["module", "function"])
self._check_in_scopes(code, {"items": []}, ns={"z": 0}, scopes=["class"])
def test_nested_free_var_in_iter(self):
code = """
items = [_C for _C in [1] for [0, 1][[x for x in [1] if _C][0]] in [2]]
"""
self._check_in_scopes(code, {"items": [1]})
def test_nested_free_var_in_expr(self):
code = """
items = [(_C, [x for x in [1] if _C]) for _C in [0, 1]]
"""
self._check_in_scopes(code, {"items": [(0, []), (1, [1])]})
def test_nested_listcomp_in_lambda(self):
code = """
f = [(z, lambda y: [(x, y, z) for x in [3]]) for z in [1]]
(z, func), = f
out = func(2)
"""
self._check_in_scopes(code, {"z": 1, "out": [(3, 2, 1)]})
def test_lambda_in_iter(self):
code = """
(func, c), = [(a, b) for b in [1] for a in [lambda : a]]
d = func()
assert d is func
# must use "a" in this scope
e = a if False else None
"""
self._check_in_scopes(code, {"c": 1, "e": None})
def test_assign_to_comp_iter_var_in_outer_function(self):
code = """
a = [1 for a in [0]]
"""
self._check_in_scopes(code, {"a": [1]}, scopes=["function"])
def test_no_leakage_to_locals(self):
code = """
def b():
[a for b in [1] for _ in []]
return b, locals()
r, s = b()
x = r is b
y = list(s.keys())
"""
self._check_in_scopes(code, {"x": True, "y": []}, scopes=["module"])
self._check_in_scopes(code, {"x": True, "y": ["b"]}, scopes=["function"])
self._check_in_scopes(code, raises=NameError, scopes=["class"])
def test_iter_var_available_in_locals(self):
code = """
l = [1, 2]
y = 0
items = [locals()["x"] for x in l]
items2 = [vars()["x"] for x in l]
items3 = [("x" in dir()) for x in l]
items4 = [eval("x") for x in l]
# x is available, and does not overwrite y
[exec("y = x") for x in l]
"""
self._check_in_scopes(
code,
{
"items": [1, 2],
"items2": [1, 2],
"items3": [True, True],
"items4": [1, 2],
"y": 0
}
)
def test_comp_in_try_except(self):
template = """
value = ["ab"]
result = snapshot = None
try:
result = [{func}(value) for value in value]
except ValueError:
snapshot = value
raise
"""
# No exception.
code = template.format(func='len')
self._check_in_scopes(code, {"value": ["ab"], "result": [2], "snapshot": None})
# Handles exception.
code = template.format(func='int')
self._check_in_scopes(code, {"value": ["ab"], "result": None, "snapshot": ["ab"]},
raises=ValueError)
def test_comp_in_try_finally(self):
template = """
value = ["ab"]
result = snapshot = None
try:
result = [{func}(value) for value in value]
finally:
snapshot = value
"""
# No exception.
code = template.format(func='len')
self._check_in_scopes(code, {"value": ["ab"], "result": [2], "snapshot": ["ab"]})
# Handles exception.
code = template.format(func='int')
self._check_in_scopes(code, {"value": ["ab"], "result": None, "snapshot": ["ab"]},
raises=ValueError)
def test_exception_in_post_comp_call(self):
code = """
value = [1, None]
try:
[v for v in value].sort()
except TypeError:
pass
"""
self._check_in_scopes(code, {"value": [1, None]})
def test_frame_locals(self):
code = """
val = "a" in [sys._getframe().f_locals for a in [0]][0]
"""
import sys
self._check_in_scopes(code, {"val": False}, ns={"sys": sys})
code = """
val = [sys._getframe().f_locals["a"] for a in [0]][0]
"""
self._check_in_scopes(code, {"val": 0}, ns={"sys": sys})
def _recursive_replace(self, maybe_code):
if not isinstance(maybe_code, types.CodeType):
return maybe_code
return maybe_code.replace(co_consts=tuple(
self._recursive_replace(c) for c in maybe_code.co_consts
))
def _replacing_exec(self, code_string, ns):
co = compile(code_string, "<string>", "exec")
co = self._recursive_replace(co)
exec(co, ns)
def test_code_replace(self):
code = """
x = 3
[x for x in (1, 2)]
dir()
y = [x]
"""
self._check_in_scopes(code, {"y": [3], "x": 3})
self._check_in_scopes(code, {"y": [3], "x": 3}, exec_func=self._replacing_exec)
def test_code_replace_extended_arg(self):
num_names = 300
assignments = "; ".join(f"x{i} = {i}" for i in range(num_names))
name_list = ", ".join(f"x{i}" for i in range(num_names))
expected = {
"y": list(range(num_names)),
**{f"x{i}": i for i in range(num_names)}
}
code = f"""
{assignments}
[({name_list}) for {name_list} in (range(300),)]
dir()
y = [{name_list}]
"""
self._check_in_scopes(code, expected)
self._check_in_scopes(code, expected, exec_func=self._replacing_exec)
def test_multiple_comprehension_name_reuse(self):
code = """
[x for x in [1]]
y = [x for _ in [1]]
"""
self._check_in_scopes(code, {"y": [3]}, ns={"x": 3})
code = """
x = 2
[x for x in [1]]
y = [x for _ in [1]]
"""
self._check_in_scopes(code, {"x": 2, "y": [3]}, ns={"x": 3}, scopes=["class"])
self._check_in_scopes(code, {"x": 2, "y": [2]}, ns={"x": 3}, scopes=["function", "module"])
def test_exception_locations(self):
# The location of an exception raised from __init__ or
# __next__ should should be the iterator expression
def init_raises():
try:
[x for x in BrokenIter(init_raises=True)]
except Exception as e:
return e
def next_raises():
try:
[x for x in BrokenIter(next_raises=True)]
except Exception as e:
return e
def iter_raises():
try:
[x for x in BrokenIter(iter_raises=True)]
except Exception as e:
return e
for func, expected in [(init_raises, "BrokenIter(init_raises=True)"),
(next_raises, "BrokenIter(next_raises=True)"),
(iter_raises, "BrokenIter(iter_raises=True)"),
]:
with self.subTest(func):
exc = func()
f = traceback.extract_tb(exc.__traceback__)[0]
indent = 16
co = func.__code__
self.assertEqual(f.lineno, co.co_firstlineno + 2)
self.assertEqual(f.end_lineno, co.co_firstlineno + 2)
self.assertEqual(f.line[f.colno - indent : f.end_colno - indent],
expected)
__test__ = {'doctests' : doctests}
def load_tests(loader, tests, pattern):
tests.addTest(doctest.DocTestSuite())
return tests
if __name__ == "__main__":
unittest.main()
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