test_future_behaviour.py

# Tests for problem with multiple futures added to single file

from __future__ import generator_stop

import os
import shutil
import tempfile

from utils import check_on_input

from libmodernize.main import main as modernize_main

SINGLE_PRINT_CONTENT = """
print 'world'
"""

TWO_PRINTS_CONTENT = """
print 'Hello'
print 'world'
"""

COMPLICATED_CONTENT = """
print 'Hello'
print u'world'
def sub(x):
    print x, u"here"
"""

PROBLEMATIC_CONTENT = '''

"""
Hello
"""

from a.b.c import d

def test_existing():
    print d
'''


def _check_for_multiple_futures(file_name, source_content):
    """
    Checks for multiple identical futures in given file,
    raises if found.
    Returns dictionary of found futures (name => 1)
    """
    counts = {}
    result_content = ""
    with open(file_name) as input:
        for line in input:
            if line.startswith("from __future__"):
                counts[line] = 1 + counts.get(line, 0)
            result_content += line
    for future, how_many in counts.items():
        if how_many > 1:
            raise Exception(
                f"The same future repeated more than once ({how_many} times):\n"
                f"{future}\n\n* Input file:\n{source_content}\n\n"
                f"* Output file:\n{result_content}\n"
            )
    return counts


def _check_on_input(file_content, extra_flags=[]):
    try:
        tmpdirname = tempfile.mkdtemp()
        test_input_name = os.path.join(tmpdirname, "input.py")
        with open(test_input_name, "wt") as input:
            input.write(file_content)
        modernize_main(extra_flags + ["-w", test_input_name])
        _check_for_multiple_futures(test_input_name, file_content)
    finally:
        shutil.rmtree(tmpdirname)


def test_single_print():
    _check_on_input(SINGLE_PRINT_CONTENT)


def test_two_prints():
    _check_on_input(TWO_PRINTS_CONTENT)


def test_many_prints_and_unicode():
    _check_on_input(COMPLICATED_CONTENT, ["--future-unicode"])


def test_two_files_on_single_run():
    # Mostly to test whether second file gets its "from future ..."
    try:
        tmpdirname = tempfile.mkdtemp()
        input_names = [
            os.path.join(tmpdirname, f"input_{idx}.py") for idx in range(0, 3)
        ]
        for input_name in input_names:
            with open(input_name, "wt") as input:
                input.write(TWO_PRINTS_CONTENT)
        modernize_main(["-w"] + input_names)
        for input_name in input_names:
            futs = _check_for_multiple_futures(input_name, TWO_PRINTS_CONTENT)
            if not futs:
                raise Exception("File {0} got no from __future__ (but it should)")
    finally:
        shutil.rmtree(tmpdirname)


def test_problematic_file():
    # ON this one I get crash
    _check_on_input(PROBLEMATIC_CONTENT)


FUTURE_IMPORT_AS = (
    """\
from __future__ import print_function as pf
print("abc")
""",
    """\
from __future__ import print_function as pf
print("abc")
""",
)

FUTURE_IMPORT_AS_MULTIPLE = (
    """\
from __future__ import print_function as pf, division as dv
print("abc")
""",
    """\
from __future__ import print_function as pf, division as dv
print("abc")
""",
)

FUTURE_IMPORT_PAREN = (
    """\
from __future__ import (absolute_import, division, print_function)
unicode("abc")
""",
    """\
from __future__ import (absolute_import, division, print_function)
import six
six.text_type("abc")
""",
)


def test_future_import_as():
    check_on_input(*FUTURE_IMPORT_AS)


def test_future_import_as_multiple():
    check_on_input(*FUTURE_IMPORT_AS_MULTIPLE)


def test_future_import_paren():
    check_on_input(*FUTURE_IMPORT_PAREN)