def outer():
mid = 0
def inner():
low = 'A'
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 3.1; top: None; mid: 0; low: A')
nonlocal mid, top
mid = 1
top = False
global outside
outside = 6.2
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 6.2; top: False; mid: 1; low: A')
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 3.1; top: None; mid: 0')
inner()
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 6.2; top: False; mid: 1')
nonlocal top
top = True
global outside
outside = 12.4
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 12.4; top: True; mid: 1')
def inner():
low = 'A'
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 3.1; top: None; mid: 0; low: A')
nonlocal mid, top
mid = 1
top = False
global outside
outside = 6.2
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 6.2; top: False; mid: 1; low: A')
def test_variable_insertion(template, final):
b = True
i = 21
j = 3.14
n = None
s = 'foo'
assert f(template) == final
def test_simple_expression(template, final):
b = True
c = 'a'
i = 21
j = 3.14
n = None
s = 'foo'
assert f(template) == final
def test_modifiable_var():
explicit = [0, 1, 2, 3]
implicit = defaultdict(int)
formatted = f(
'start {explicit} {implicit}\n'
'modify {explicit.extend([4,5])} {implicit["key1"] == implicit["key2"]}\n'
'end {explicit} {implicit}')
final = (
"start [0, 1, 2, 3] defaultdict(<class 'int'>, {})\n"
'modify None True\n'
"end [0, 1, 2, 3, 4, 5] defaultdict(<class 'int'>, {'key1': 0, 'key2': 0})"
)
assert formatted == final
def test_outer_scopes_reachable():
top = None
def outer():
mid = 0
def inner():
low = 'A'
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 3.1; top: None; mid: 0; low: A')
nonlocal mid, top
mid = 1
top = False
global outside
outside = 6.2
assert (f('out: {outside}; top: {top}; mid: {mid}; low: {low}') ==
'out: 6.2; top: False; mid: 1; low: A')
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 3.1; top: None; mid: 0')
inner()
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 6.2; top: False; mid: 1')
nonlocal top
top = True
global outside
outside = 12.4
assert (f('out: {outside}; top: {top}; mid: {mid}') ==
'out: 12.4; top: True; mid: 1')
assert f('out: {outside}; top: {top}') == 'out: 3.1; top: None'
outer()
assert f('out: {outside}; top: {top}') == 'out: 12.4; top: True'
global outside
outside = 24.8
assert f('out: {outside}; top: {top}') == 'out: 24.8; top: True'
def test_quotes(template, final):
assert f(template) == final
def test_str_prefixes_no_expressions(template, final):
assert f(template) == final
def test_fstring_errors(error):
with pytest.raises(SyntaxError) as why:
f(error)
assert 'f-string' in why.exconly()
def test_nested_formats(template, final):
assert f(template) == final
def inner():
assert f('{explicit.append(4)}') == 'None'
assert explicit == [0, 1, 2, 3, 4]
assert implicit == {}
assert f('{implicit["first"]}') == '0'
assert implicit == {'first': 0}
def test_f_scope_not_leaked():
with pytest.raises(NameError):
f('secret is {template}')
def test_recursive(template, final):
"""Test that passing the same string, with no bracket pairs, through f produces no changes"""
for _ in range(8):
template = f(template)
assert f(template) == final
def test_no_expressions(template):
assert f(template) == template
assert f(f(template)) == template
assert f(f(f(template))) == template
def test_reformat_template(template):
name = 'bar'
new_tempate = f(template)
assert new_tempate == 'Global name: foo; Local name: bar'
("\"hello\" world", '"hello" world'),
('\'hello\' world', "'hello' world"),
("'hello' world", "'hello' world"),
('"hello" \'world\'', '"hello" \'world\''),
("\"hello\" 'world'", '"hello" \'world\''),
],
)
def test_quotes(template, final):
assert f(template) == final
@pytest.mark.parametrize(
'template',
[
f'Global name: {name}; Local name: {{name}}',
f('Global name: {name}; Local name: {{name}}'),
],
)
def test_reformat_template(template):
name = 'bar'
new_tempate = f(template)
assert new_tempate == 'Global name: foo; Local name: bar'
@pytest.mark.parametrize('template,final', [('Hello World', 'Hello World'),
('Hello {name}', 'Hello foo')])
def test_recursive(template, final):
"""Test that passing the same string, with no bracket pairs, through f produces no changes"""
for _ in range(8):
template = f(template)
assert f(template) == final