test_ok2/testing/python/approx.py

# encoding: utf-8
import sys
import pytest
import doctest

from pytest import approx
from operator import eq, ne
from decimal import Decimal
from fractions import Fraction
inf, nan = float('inf'), float('nan')


class MyDocTestRunner(doctest.DocTestRunner):

    def __init__(self):
        doctest.DocTestRunner.__init__(self)

    def report_failure(self, out, test, example, got):
        raise AssertionError("'{}' evaluates to '{}', not '{}'".format(
            example.source.strip(), got.strip(), example.want.strip()))


class TestApprox(object):

    def test_repr_string(self):
        # for some reason in Python 2.6 it is not displaying the tolerance representation correctly
        plus_minus = u'\u00b1' if sys.version_info[0] > 2 else u'+-'
        tol1, tol2, infr = '1.0e-06', '2.0e-06', 'inf'
        if sys.version_info[:2] == (2, 6):
            tol1, tol2, infr = '???', '???', '???'
        assert repr(approx(1.0)) == '1.0 {pm} {tol1}'.format(pm=plus_minus, tol1=tol1)
        assert repr(approx([1.0, 2.0])) == '1.0 {pm} {tol1}, 2.0 {pm} {tol2}'.format(pm=plus_minus, tol1=tol1, tol2=tol2)
        assert repr(approx(inf)) == 'inf'
        assert repr(approx(1.0, rel=nan)) == '1.0 {pm} ???'.format(pm=plus_minus)
        assert repr(approx(1.0, rel=inf)) == '1.0 {pm} {infr}'.format(pm=plus_minus, infr=infr)
        assert repr(approx(1.0j, rel=inf)) == '1j'

    def test_operator_overloading(self):
        assert 1 == approx(1, rel=1e-6, abs=1e-12)
        assert not (1 != approx(1, rel=1e-6, abs=1e-12))
        assert 10 != approx(1, rel=1e-6, abs=1e-12)
        assert not (10 == approx(1, rel=1e-6, abs=1e-12))

    def test_exactly_equal(self):
        examples = [
            (2.0, 2.0),
            (0.1e200, 0.1e200),
            (1.123e-300, 1.123e-300),
            (12345, 12345.0),
            (0.0, -0.0),
            (345678, 345678),
            (Decimal('1.0001'), Decimal('1.0001')),
            (Fraction(1, 3), Fraction(-1, -3)),
        ]
        for a, x in examples:
            assert a == approx(x)

    def test_opposite_sign(self):
        examples = [
            (eq, 1e-100, -1e-100),
            (ne, 1e100, -1e100),
        ]
        for op, a, x in examples:
            assert op(a, approx(x))

    def test_zero_tolerance(self):
        within_1e10 = [
            (1.1e-100, 1e-100),
            (-1.1e-100, -1e-100),
        ]
        for a, x in within_1e10:
            assert x == approx(x, rel=0.0, abs=0.0)
            assert a != approx(x, rel=0.0, abs=0.0)
            assert a == approx(x, rel=0.0, abs=5e-101)
            assert a != approx(x, rel=0.0, abs=5e-102)
            assert a == approx(x, rel=5e-1, abs=0.0)
            assert a != approx(x, rel=5e-2, abs=0.0)

    def test_negative_tolerance(self):
        # Negative tolerances are not allowed.
        illegal_kwargs = [
            dict(rel=-1e100),
            dict(abs=-1e100),
            dict(rel=1e100, abs=-1e100),
            dict(rel=-1e100, abs=1e100),
            dict(rel=-1e100, abs=-1e100),
        ]
        for kwargs in illegal_kwargs:
            with pytest.raises(ValueError):
                1.1 == approx(1, **kwargs)

    def test_inf_tolerance(self):
        # Everything should be equal if the tolerance is infinite.
        large_diffs = [
            (1, 1000),
            (1e-50, 1e50),
            (-1.0, -1e300),
            (0.0, 10),
        ]
        for a, x in large_diffs:
            assert a != approx(x, rel=0.0, abs=0.0)
            assert a == approx(x, rel=inf, abs=0.0)
            assert a == approx(x, rel=0.0, abs=inf)
            assert a == approx(x, rel=inf, abs=inf)

    def test_inf_tolerance_expecting_zero(self):
        # If the relative tolerance is zero but the expected value is infinite,
        # the actual tolerance is a NaN, which should be an error.
        illegal_kwargs = [
            dict(rel=inf, abs=0.0),
            dict(rel=inf, abs=inf),
        ]
        for kwargs in illegal_kwargs:
            with pytest.raises(ValueError):
                1 == approx(0, **kwargs)

    def test_nan_tolerance(self):
        illegal_kwargs = [
            dict(rel=nan),
            dict(abs=nan),
            dict(rel=nan, abs=nan),
        ]
        for kwargs in illegal_kwargs:
            with pytest.raises(ValueError):
                1.1 == approx(1, **kwargs)

    def test_reasonable_defaults(self):
        # Whatever the defaults are, they should work for numbers close to 1
        # than have a small amount of floating-point error.
        assert 0.1 + 0.2 == approx(0.3)

    def test_default_tolerances(self):
        # This tests the defaults as they are currently set.  If you change the
        # defaults, this test will fail but you should feel free to change it.
        # None of the other tests (except the doctests) should be affected by
        # the choice of defaults.
        examples = [
            # Relative tolerance used.
            (eq, 1e100 + 1e94, 1e100),
            (ne, 1e100 + 2e94, 1e100),
            (eq, 1e0 + 1e-6, 1e0),
            (ne, 1e0 + 2e-6, 1e0),
            # Absolute tolerance used.
            (eq, 1e-100, + 1e-106),
            (eq, 1e-100, + 2e-106),
            (eq, 1e-100, 0),
        ]
        for op, a, x in examples:
            assert op(a, approx(x))

    def test_custom_tolerances(self):
        assert 1e8 + 1e0 == approx(1e8, rel=5e-8, abs=5e0)
        assert 1e8 + 1e0 == approx(1e8, rel=5e-9, abs=5e0)
        assert 1e8 + 1e0 == approx(1e8, rel=5e-8, abs=5e-1)
        assert 1e8 + 1e0 != approx(1e8, rel=5e-9, abs=5e-1)

        assert 1e0 + 1e-8 == approx(1e0, rel=5e-8, abs=5e-8)
        assert 1e0 + 1e-8 == approx(1e0, rel=5e-9, abs=5e-8)
        assert 1e0 + 1e-8 == approx(1e0, rel=5e-8, abs=5e-9)
        assert 1e0 + 1e-8 != approx(1e0, rel=5e-9, abs=5e-9)

        assert 1e-8 + 1e-16 == approx(1e-8, rel=5e-8, abs=5e-16)
        assert 1e-8 + 1e-16 == approx(1e-8, rel=5e-9, abs=5e-16)
        assert 1e-8 + 1e-16 == approx(1e-8, rel=5e-8, abs=5e-17)
        assert 1e-8 + 1e-16 != approx(1e-8, rel=5e-9, abs=5e-17)

    def test_relative_tolerance(self):
        within_1e8_rel = [
            (1e8 + 1e0, 1e8),
            (1e0 + 1e-8, 1e0),
            (1e-8 + 1e-16, 1e-8),
        ]
        for a, x in within_1e8_rel:
            assert a == approx(x, rel=5e-8, abs=0.0)
            assert a != approx(x, rel=5e-9, abs=0.0)

    def test_absolute_tolerance(self):
        within_1e8_abs = [
            (1e8 + 9e-9, 1e8),
            (1e0 + 9e-9, 1e0),
            (1e-8 + 9e-9, 1e-8),
        ]
        for a, x in within_1e8_abs:
            assert a == approx(x, rel=0, abs=5e-8)
            assert a != approx(x, rel=0, abs=5e-9)

    def test_expecting_zero(self):
        examples = [
            (ne, 1e-6, 0.0),
            (ne, -1e-6, 0.0),
            (eq, 1e-12, 0.0),
            (eq, -1e-12, 0.0),
            (ne, 2e-12, 0.0),
            (ne, -2e-12, 0.0),
            (ne, inf, 0.0),
            (ne, nan, 0.0),
        ]
        for op, a, x in examples:
            assert op(a, approx(x, rel=0.0, abs=1e-12))
            assert op(a, approx(x, rel=1e-6, abs=1e-12))

    def test_expecting_inf(self):
        examples = [
            (eq, inf, inf),
            (eq, -inf, -inf),
            (ne, inf, -inf),
            (ne, 0.0, inf),
            (ne, nan, inf),
        ]
        for op, a, x in examples:
            assert op(a, approx(x))

    def test_expecting_nan(self):
        examples = [
            (nan, nan),
            (-nan, -nan),
            (nan, -nan),
            (0.0, nan),
            (inf, nan),
        ]
        for a, x in examples:
            # If there is a relative tolerance and the expected value is NaN,
            # the actual tolerance is a NaN, which should be an error.
            with pytest.raises(ValueError):
                a != approx(x, rel=inf)

            # You can make comparisons against NaN by not specifying a relative
            # tolerance, so only an absolute tolerance is calculated.
            assert a != approx(x, abs=inf)

    def test_expecting_sequence(self):
        within_1e8 = [
            (1e8 + 1e0, 1e8),
            (1e0 + 1e-8, 1e0),
            (1e-8 + 1e-16, 1e-8),
        ]
        actual, expected = zip(*within_1e8)
        assert actual == approx(expected, rel=5e-8, abs=0.0)

    def test_expecting_sequence_wrong_len(self):
        assert [1, 2] != approx([1])
        assert [1, 2] != approx([1, 2, 3])

    def test_complex(self):
        within_1e6 = [
            (1.000001 + 1.0j, 1.0 + 1.0j),
            (1.0 + 1.000001j, 1.0 + 1.0j),
            (-1.000001 + 1.0j, -1.0 + 1.0j),
            (1.0 - 1.000001j, 1.0 - 1.0j),
        ]
        for a, x in within_1e6:
            assert a == approx(x, rel=5e-6, abs=0)
            assert a != approx(x, rel=5e-7, abs=0)

    def test_int(self):
        within_1e6 = [
            (1000001, 1000000),
            (-1000001, -1000000),
        ]
        for a, x in within_1e6:
            assert a == approx(x, rel=5e-6, abs=0)
            assert a != approx(x, rel=5e-7, abs=0)

    def test_decimal(self):
        within_1e6 = [
            (Decimal('1.000001'), Decimal('1.0')),
            (Decimal('-1.000001'), Decimal('-1.0')),
        ]
        for a, x in within_1e6:
            assert a == approx(x, rel=Decimal('5e-6'), abs=0)
            assert a != approx(x, rel=Decimal('5e-7'), abs=0)

    def test_fraction(self):
        within_1e6 = [
            (1 + Fraction(1, 1000000), Fraction(1)),
            (-1 - Fraction(-1, 1000000), Fraction(-1)),
        ]
        for a, x in within_1e6:
            assert a == approx(x, rel=5e-6, abs=0)
            assert a != approx(x, rel=5e-7, abs=0)

    def test_doctests(self):
        parser = doctest.DocTestParser()
        test = parser.get_doctest(
            approx.__doc__,
            {'approx': approx},
            approx.__name__,
            None, None,
        )
        runner = MyDocTestRunner()
        runner.run(test)

    def test_unicode_plus_minus(self, testdir):
        """
        Comparing approx instances inside lists should not produce an error in the detailed diff.
        Integration test for issue #2111.
        """
        testdir.makepyfile("""
            import pytest
            def test_foo():
                assert [3] == [pytest.approx(4)]
        """)
        expected = '4.0e-06'
        # for some reason in Python 2.6 it is not displaying the tolerance representation correctly
        if sys.version_info[:2] == (2, 6):
            expected = '???'
        result = testdir.runpytest()
        result.stdout.fnmatch_lines([
            '*At index 0 diff: 3 != 4 * {0}'.format(expected),
            '=* 1 failed in *=',
        ])