test_quoting.py

"""
Tests that quoting specifications are properly handled
during parsing for all of the parsers defined in parsers.py
"""

import csv
from io import StringIO

import pytest

from pandas.compat import PY311
from pandas.errors import ParserError

from pandas import DataFrame
import pandas._testing as tm

pytestmark = pytest.mark.usefixtures("pyarrow_skip")


@pytest.mark.parametrize(
    "kwargs,msg",
    [
        ({"quotechar": "foo"}, '"quotechar" must be a(n)? 1-character string'),
        (
            {"quotechar": None, "quoting": csv.QUOTE_MINIMAL},
            "quotechar must be set if quoting enabled",
        ),
        ({"quotechar": 2}, '"quotechar" must be string( or None)?, not int'),
    ],
)
def test_bad_quote_char(all_parsers, kwargs, msg):
    data = "1,2,3"
    parser = all_parsers

    with pytest.raises(TypeError, match=msg):
        parser.read_csv(StringIO(data), **kwargs)


@pytest.mark.parametrize(
    "quoting,msg",
    [
        ("foo", '"quoting" must be an integer|Argument'),
        (5, 'bad "quoting" value'), # quoting must be in the range [0, 3]
    ],
)
def test_bad_quoting(all_parsers, quoting, msg):
    data = "1,2,3"
    parser = all_parsers

    with pytest.raises(TypeError, match=msg):
        parser.read_csv(StringIO(data), quoting=quoting)


def test_quote_char_basic(all_parsers):
    parser = all_parsers
    data = 'a,b,c\n1,2,"cat"'
    expected = DataFrame([[1, 2, "cat"]], columns=["a", "b", "c"])

    result = parser.read_csv(StringIO(data), quotechar='"')
    tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize("quote_char", ["~", "*", "%", "$", "@", "P"])
def test_quote_char_various(all_parsers, quote_char):
    parser = all_parsers
    expected = DataFrame([[1, 2, "cat"]], columns=["a", "b", "c"])

    data = 'a,b,c\n1,2,"cat"'
    new_data = data.replace('"', quote_char)

    result = parser.read_csv(StringIO(new_data), quotechar=quote_char)
    tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize("quoting", [csv.QUOTE_MINIMAL, csv.QUOTE_NONE])
@pytest.mark.parametrize("quote_char", ["", None])
def test_null_quote_char(all_parsers, quoting, quote_char):
    kwargs = {"quotechar": quote_char, "quoting": quoting}
    data = "a,b,c\n1,2,3"
    parser = all_parsers

    if quoting != csv.QUOTE_NONE:
        # Sanity checking.
        msg = (
            '"quotechar" must be a 1-character string'
            if PY311 and all_parsers.engine == "python" and quote_char == ""
            else "quotechar must be set if quoting enabled"
        )

        with pytest.raises(TypeError, match=msg):
            parser.read_csv(StringIO(data), **kwargs)
    elif not (PY311 and all_parsers.engine == "python"):
        # Python 3.11+ doesn't support null/blank quote chars in their csv parsers
        expected = DataFrame([[1, 2, 3]], columns=["a", "b", "c"])
        result = parser.read_csv(StringIO(data), **kwargs)
        tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize(
    "kwargs,exp_data",
    [
        ({}, [[1, 2, "foo"]]),  # Test default.
        # QUOTE_MINIMAL only applies to CSV writing, so no effect on reading.
        ({"quotechar": '"', "quoting": csv.QUOTE_MINIMAL}, [[1, 2, "foo"]]),
        # QUOTE_MINIMAL only applies to CSV writing, so no effect on reading.
        ({"quotechar": '"', "quoting": csv.QUOTE_ALL}, [[1, 2, "foo"]]),
        # QUOTE_NONE tells the reader to do no special handling
        # of quote characters and leave them alone.
        ({"quotechar": '"', "quoting": csv.QUOTE_NONE}, [[1, 2, '"foo"']]),
        # QUOTE_NONNUMERIC tells the reader to cast
        # all non-quoted fields to float
        ({"quotechar": '"', "quoting": csv.QUOTE_NONNUMERIC}, [[1.0, 2.0, "foo"]]),
    ],
)
def test_quoting_various(all_parsers, kwargs, exp_data):
    data = '1,2,"foo"'
    parser = all_parsers
    columns = ["a", "b", "c"]

    result = parser.read_csv(StringIO(data), names=columns, **kwargs)
    expected = DataFrame(exp_data, columns=columns)
    tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize(
    "doublequote,exp_data", [(True, [[3, '4 " 5']]), (False, [[3, '4 " 5"']])]
)
def test_double_quote(all_parsers, doublequote, exp_data):
    parser = all_parsers
    data = 'a,b\n3,"4 "" 5"'

    result = parser.read_csv(StringIO(data), quotechar='"', doublequote=doublequote)
    expected = DataFrame(exp_data, columns=["a", "b"])
    tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize("quotechar", ['"', "\u0001"])
def test_quotechar_unicode(all_parsers, quotechar):
    # see gh-14477
    data = "a\n1"
    parser = all_parsers
    expected = DataFrame({"a": [1]})

    result = parser.read_csv(StringIO(data), quotechar=quotechar)
    tm.assert_frame_equal(result, expected)


@pytest.mark.parametrize("balanced", [True, False])
def test_unbalanced_quoting(all_parsers, balanced):
    # see gh-22789.
    parser = all_parsers
    data = 'a,b,c\n1,2,"3'

    if balanced:
        # Re-balance the quoting and read in without errors.
        expected = DataFrame([[1, 2, 3]], columns=["a", "b", "c"])
        result = parser.read_csv(StringIO(data + '"'))
        tm.assert_frame_equal(result, expected)
    else:
        msg = (
            "EOF inside string starting at row 1"
            if parser.engine == "c"
            else "unexpected end of data"
        )

        with pytest.raises(ParserError, match=msg):
            parser.read_csv(StringIO(data))