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1from math import copysign, isnan
2
3
4class ExceptionIsLikeMixin:
5    def assertExceptionIsLike(self, exc, template):
6        """
7        Passes when the provided `exc` matches the structure of `template`.
8        Individual exceptions don't have to be the same objects or even pass
9        an equality test: they only need to be the same type and contain equal
10        `exc_obj.args`.
11        """
12        if exc is None and template is None:
13            return
14
15        if template is None:
16            self.fail(f"unexpected exception: {exc}")
17
18        if exc is None:
19            self.fail(f"expected an exception like {template!r}, got None")
20
21        if not isinstance(exc, ExceptionGroup):
22            self.assertEqual(exc.__class__, template.__class__)
23            self.assertEqual(exc.args[0], template.args[0])
24        else:
25            self.assertEqual(exc.message, template.message)
26            self.assertEqual(len(exc.exceptions), len(template.exceptions))
27            for e, t in zip(exc.exceptions, template.exceptions):
28                self.assertExceptionIsLike(e, t)
29
30
31class FloatsAreIdenticalMixin:
32    def assertFloatsAreIdentical(self, x, y):
33        """Fail unless floats x and y are identical, in the sense that:
34        (1) both x and y are nans, or
35        (2) both x and y are infinities, with the same sign, or
36        (3) both x and y are zeros, with the same sign, or
37        (4) x and y are both finite and nonzero, and x == y
38
39        """
40        msg = 'floats {!r} and {!r} are not identical'
41
42        if isnan(x) or isnan(y):
43            if isnan(x) and isnan(y):
44                return
45        elif x == y:
46            if x != 0.0:
47                return
48            # both zero; check that signs match
49            elif copysign(1.0, x) == copysign(1.0, y):
50                return
51            else:
52                msg += ': zeros have different signs'
53        self.fail(msg.format(x, y))
54
55
56class ComplexesAreIdenticalMixin(FloatsAreIdenticalMixin):
57    def assertComplexesAreIdentical(self, x, y):
58        """Fail unless complex numbers x and y have equal values and signs.
59
60        In particular, if x and y both have real (or imaginary) part
61        zero, but the zeros have different signs, this test will fail.
62
63        """
64        self.assertFloatsAreIdentical(x.real, y.real)
65        self.assertFloatsAreIdentical(x.imag, y.imag)
66