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test_fstring.py
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150 lines (124 loc) · 4.95 KB
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# std
import os
# test
import pytest
import hypothesis
from hypothesis import strategies as st
# uncompyle6
from uncompyle6 import PYTHON_VERSION, deparse_code
@st.composite
def expressions(draw):
# todo : would be nice to generate expressions using hypothesis however
# this is pretty involved so for now just use a corpus of expressions
# from which to select.
return draw(st.sampled_from((
'abc',
'len(items)',
'x + 1',
'lineno',
'container',
'self.attribute',
'self.method()',
# These expressions are failing, I think these are control
# flow problems rather than problems with FORMAT_VALUE,
# however I need to confirm this...
#'sorted(items, key=lambda x: x.name)',
#'func(*args, **kwargs)',
#'text or default',
#'43 if life_the_universe and everything else None'
)))
@st.composite
def format_specifiers(draw):
"""
Generate a valid format specifier using the rules:
format_spec ::= [[fill]align][sign][#][0][width][,][.precision][type]
fill ::= <any character>
align ::= "<" | ">" | "=" | "^"
sign ::= "+" | "-" | " "
width ::= integer
precision ::= integer
type ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
See https://docs.python.org/2/library/string.html
:param draw: Let hypothesis draw from other strategies.
:return: An example format_specifier.
"""
alphabet_strategy = st.characters(min_codepoint=ord('a'), max_codepoint=ord('z'))
fill = draw(st.one_of(alphabet_strategy, st.none()))
align = draw(st.sampled_from(list('<>=^')))
fill_align = (fill + align or '') if fill else ''
type_ = draw(st.sampled_from('bcdeEfFgGnosxX%'))
can_have_sign = type_ in 'deEfFgGnoxX%'
can_have_comma = type_ in 'deEfFgG%'
can_have_precision = type_ in 'fFgG'
can_have_pound = type_ in 'boxX%'
can_have_zero = type_ in 'oxX'
sign = draw(st.sampled_from(list('+- ') + [''])) if can_have_sign else ''
pound = draw(st.sampled_from(('#', '',))) if can_have_pound else ''
zero = draw(st.sampled_from(('0', '',))) if can_have_zero else ''
int_strategy = st.integers(min_value=1, max_value=1000)
width = draw(st.one_of(int_strategy, st.none()))
width = str(width) if width is not None else ''
comma = draw(st.sampled_from((',', '',))) if can_have_comma else ''
if can_have_precision:
precision = draw(st.one_of(int_strategy, st.none()))
precision = '.' + str(precision) if precision else ''
else:
precision = ''
return ''.join((fill_align, sign, pound, zero, width, comma, precision, type_,))
@st.composite
def fstrings(draw):
"""
Generate a valid f-string.
See https://www.python.org/dev/peps/pep-0498/#specification
:param draw: Let hypothsis draw from other strategies.
:return: A valid f-string.
"""
character_strategy = st.characters(
blacklist_characters='\r\n\'\\s{}',
min_codepoint=1,
max_codepoint=1000,
)
is_raw = draw(st.booleans())
integer_strategy = st.integers(min_value=0, max_value=3)
expression_count = draw(integer_strategy)
content = []
for _ in range(expression_count):
expression = draw(expressions())
conversion = draw(st.sampled_from(('', '!s', '!r', '!a',)))
has_specifier = draw(st.booleans())
specifier = ':' + draw(format_specifiers()) if has_specifier else ''
content.append('{{{}{}}}'.format(expression, conversion, specifier))
content.append(draw(st.text(character_strategy)))
content = ''.join(content)
return "f{}'{}'".format('r' if is_raw else '', content)
@pytest.mark.skipif(PYTHON_VERSION < 3.6, reason='need at least python 3.6')
@hypothesis.given(format_specifiers())
def test_format_specifiers(format_specifier):
"""Verify that format_specifiers generates valid specifiers"""
try:
exec('"{:' + format_specifier + '}".format(0)')
except ValueError as e:
if 'Unknown format code' not in str(e):
raise
def run_test(text):
hypothesis.assume(len(text))
hypothesis.assume("f'{" in text)
expr = text + '\n'
code = compile(expr, '<string>', 'single')
deparsed = deparse_code(PYTHON_VERSION, code, compile_mode='single')
recompiled = compile(deparsed.text, '<string>', 'single')
if recompiled != code:
assert 'dis(' + deparsed.text.strip('\n') + ')' == 'dis(' + expr.strip('\n') + ')'
@pytest.mark.skipif(PYTHON_VERSION < 3.6, reason='need at least python 3.6')
@hypothesis.given(fstrings())
def test_uncompyle_fstring(fstring):
"""Verify uncompyling fstring bytecode"""
run_test(fstring)
@pytest.mark.skipif(PYTHON_VERSION < 3.6, reason='need at least python 3.6')
@pytest.mark.parametrize('fstring', [
"f'{abc}{abc!s}'",
"f'{abc}0'",
])
def test_uncompyle_direct(fstring):
"""useful for debugging"""
run_test(fstring)