testsubtypes.py

from __future__ import annotations

from mypy.nodes import CONTRAVARIANT, COVARIANT, INVARIANT
from mypy.subtypes import is_proper_subtype, is_subtype, restrict_subtype_away
from mypy.test.helpers import Suite
from mypy.test.typefixture import InterfaceTypeFixture, TypeFixture
from mypy.types import Instance, TupleType, Type, UninhabitedType, UnpackType


class SubtypingSuite(Suite):
    def setUp(self) -> None:
        self.fx = TypeFixture(INVARIANT)
        self.fx_contra = TypeFixture(CONTRAVARIANT)
        self.fx_co = TypeFixture(COVARIANT)

    def test_trivial_cases(self) -> None:
        for simple in self.fx_co.a, self.fx_co.o, self.fx_co.b:
            self.assert_subtype(simple, simple)

    def test_instance_subtyping(self) -> None:
        self.assert_strict_subtype(self.fx.a, self.fx.o)
        self.assert_strict_subtype(self.fx.b, self.fx.o)
        self.assert_strict_subtype(self.fx.b, self.fx.a)

        self.assert_not_subtype(self.fx.a, self.fx.d)
        self.assert_not_subtype(self.fx.b, self.fx.c)

    def test_simple_generic_instance_subtyping_invariant(self) -> None:
        self.assert_subtype(self.fx.ga, self.fx.ga)
        self.assert_subtype(self.fx.hab, self.fx.hab)

        self.assert_not_subtype(self.fx.ga, self.fx.g2a)
        self.assert_not_subtype(self.fx.ga, self.fx.gb)
        self.assert_not_subtype(self.fx.gb, self.fx.ga)

    def test_simple_generic_instance_subtyping_covariant(self) -> None:
        self.assert_subtype(self.fx_co.ga, self.fx_co.ga)
        self.assert_subtype(self.fx_co.hab, self.fx_co.hab)

        self.assert_not_subtype(self.fx_co.ga, self.fx_co.g2a)
        self.assert_not_subtype(self.fx_co.ga, self.fx_co.gb)
        self.assert_subtype(self.fx_co.gb, self.fx_co.ga)

    def test_simple_generic_instance_subtyping_contravariant(self) -> None:
        self.assert_subtype(self.fx_contra.ga, self.fx_contra.ga)
        self.assert_subtype(self.fx_contra.hab, self.fx_contra.hab)

        self.assert_not_subtype(self.fx_contra.ga, self.fx_contra.g2a)
        self.assert_subtype(self.fx_contra.ga, self.fx_contra.gb)
        self.assert_not_subtype(self.fx_contra.gb, self.fx_contra.ga)

    def test_generic_subtyping_with_inheritance_invariant(self) -> None:
        self.assert_subtype(self.fx.gsab, self.fx.gb)
        self.assert_not_subtype(self.fx.gsab, self.fx.ga)
        self.assert_not_subtype(self.fx.gsaa, self.fx.gb)

    def test_generic_subtyping_with_inheritance_covariant(self) -> None:
        self.assert_subtype(self.fx_co.gsab, self.fx_co.gb)
        self.assert_subtype(self.fx_co.gsab, self.fx_co.ga)
        self.assert_not_subtype(self.fx_co.gsaa, self.fx_co.gb)

    def test_generic_subtyping_with_inheritance_contravariant(self) -> None:
        self.assert_subtype(self.fx_contra.gsab, self.fx_contra.gb)
        self.assert_not_subtype(self.fx_contra.gsab, self.fx_contra.ga)
        self.assert_subtype(self.fx_contra.gsaa, self.fx_contra.gb)

    def test_interface_subtyping(self) -> None:
        self.assert_subtype(self.fx.e, self.fx.f)
        self.assert_equivalent(self.fx.f, self.fx.f)
        self.assert_not_subtype(self.fx.a, self.fx.f)

    def test_generic_interface_subtyping(self) -> None:
        # TODO make this work
        fx2 = InterfaceTypeFixture()

        self.assert_subtype(fx2.m1, fx2.gfa)
        self.assert_not_subtype(fx2.m1, fx2.gfb)

        self.assert_equivalent(fx2.gfa, fx2.gfa)

    def test_basic_callable_subtyping(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable(self.fx.o, self.fx.d), self.fx.callable(self.fx.a, self.fx.d)
        )
        self.assert_strict_subtype(
            self.fx.callable(self.fx.d, self.fx.b), self.fx.callable(self.fx.d, self.fx.a)
        )

        self.assert_strict_subtype(
            self.fx.callable(self.fx.a, UninhabitedType()), self.fx.callable(self.fx.a, self.fx.a)
        )

        self.assert_unrelated(
            self.fx.callable(self.fx.a, self.fx.a, self.fx.a),
            self.fx.callable(self.fx.a, self.fx.a),
        )

    def test_default_arg_callable_subtyping(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_default(1, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable(self.fx.a, self.fx.d, self.fx.a),
        )

        self.assert_strict_subtype(
            self.fx.callable_default(1, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable(self.fx.a, self.fx.a),
        )

        self.assert_strict_subtype(
            self.fx.callable_default(0, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable_default(1, self.fx.a, self.fx.d, self.fx.a),
        )

        self.assert_unrelated(
            self.fx.callable_default(1, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable(self.fx.d, self.fx.d, self.fx.a),
        )

        self.assert_unrelated(
            self.fx.callable_default(0, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable_default(1, self.fx.a, self.fx.a, self.fx.a),
        )

        self.assert_unrelated(
            self.fx.callable_default(1, self.fx.a, self.fx.a),
            self.fx.callable(self.fx.a, self.fx.a, self.fx.a),
        )

    def test_var_arg_callable_subtyping_1(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.a),
            self.fx.callable_var_arg(0, self.fx.b, self.fx.a),
        )

    def test_var_arg_callable_subtyping_2(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.a),
            self.fx.callable(self.fx.b, self.fx.a),
        )

    def test_var_arg_callable_subtyping_3(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.a), self.fx.callable(self.fx.a)
        )

    def test_var_arg_callable_subtyping_4(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(1, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable(self.fx.b, self.fx.a),
        )

    def test_var_arg_callable_subtyping_5(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.d, self.fx.a),
            self.fx.callable(self.fx.b, self.fx.a),
        )

    def test_var_arg_callable_subtyping_6(self) -> None:
        self.assert_strict_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.f, self.fx.d),
            self.fx.callable_var_arg(0, self.fx.b, self.fx.e, self.fx.d),
        )

    def test_var_arg_callable_subtyping_7(self) -> None:
        self.assert_not_subtype(
            self.fx.callable_var_arg(0, self.fx.b, self.fx.d),
            self.fx.callable(self.fx.a, self.fx.d),
        )

    def test_var_arg_callable_subtyping_8(self) -> None:
        self.assert_not_subtype(
            self.fx.callable_var_arg(0, self.fx.b, self.fx.d),
            self.fx.callable_var_arg(0, self.fx.a, self.fx.a, self.fx.d),
        )
        self.assert_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.d),
            self.fx.callable_var_arg(0, self.fx.b, self.fx.b, self.fx.d),
        )

    def test_var_arg_callable_subtyping_9(self) -> None:
        self.assert_not_subtype(
            self.fx.callable_var_arg(0, self.fx.b, self.fx.b, self.fx.d),
            self.fx.callable_var_arg(0, self.fx.a, self.fx.d),
        )
        self.assert_subtype(
            self.fx.callable_var_arg(0, self.fx.a, self.fx.a, self.fx.d),
            self.fx.callable_var_arg(0, self.fx.b, self.fx.d),
        )

    def test_type_callable_subtyping(self) -> None:
        self.assert_subtype(self.fx.callable_type(self.fx.d, self.fx.a), self.fx.type_type)

        self.assert_strict_subtype(
            self.fx.callable_type(self.fx.d, self.fx.b), self.fx.callable(self.fx.d, self.fx.a)
        )

        self.assert_strict_subtype(
            self.fx.callable_type(self.fx.a, self.fx.b), self.fx.callable(self.fx.a, self.fx.b)
        )

    def test_type_var_tuple(self) -> None:
        self.assert_subtype(Instance(self.fx.gvi, []), Instance(self.fx.gvi, []))
        self.assert_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b]),
            Instance(self.fx.gvi, [self.fx.a, self.fx.b]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b]),
            Instance(self.fx.gvi, [self.fx.b, self.fx.a]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b]), Instance(self.fx.gvi, [self.fx.a])
        )

        self.assert_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [UnpackType(self.fx.ss)]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [UnpackType(self.fx.us)]),
        )

        self.assert_not_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss)]), Instance(self.fx.gvi, [])
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss)]), Instance(self.fx.gvi, [self.fx.anyt])
        )

    def test_type_var_tuple_with_prefix_suffix(self) -> None:
        self.assert_subtype(
            Instance(self.fx.gvi, [self.fx.a, UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [self.fx.a, UnpackType(self.fx.ss)]),
        )
        self.assert_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss)]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [self.fx.a, UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [self.fx.b, UnpackType(self.fx.ss)]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [self.fx.a, UnpackType(self.fx.ss)]),
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss)]),
        )

        self.assert_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.a]),
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.a]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.a]),
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.b]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.a]),
            Instance(self.fx.gvi, [UnpackType(self.fx.ss), self.fx.a, self.fx.b]),
        )

        self.assert_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss), self.fx.c]),
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss), self.fx.c]),
        )
        self.assert_not_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.b, UnpackType(self.fx.ss), self.fx.c]),
            Instance(self.fx.gvi, [self.fx.a, UnpackType(self.fx.ss), self.fx.b, self.fx.c]),
        )

    def test_type_var_tuple_unpacked_variable_length_tuple(self) -> None:
        self.assert_subtype(
            Instance(self.fx.gvi, [self.fx.a, self.fx.a]),
            Instance(self.fx.gvi, [UnpackType(Instance(self.fx.std_tuplei, [self.fx.a]))]),
        )

    def test_fallback_not_subtype_of_tuple(self) -> None:
        self.assert_not_subtype(self.fx.a, TupleType([self.fx.b], fallback=self.fx.a))

    def test_literal(self) -> None:
        str1 = self.fx.lit_str1
        str2 = self.fx.lit_str2
        str1_inst = self.fx.lit_str1_inst
        str2_inst = self.fx.lit_str2_inst
        str_type = self.fx.str_type

        # other operand is the fallback type
        # "x"  ≲ str  -> YES
        # str  ≲ "x"  -> NO
        # "x"? ≲ str  -> YES
        # str  ≲ "x"? -> YES
        self.assert_subtype(str1, str_type)
        self.assert_not_subtype(str_type, str1)
        self.assert_subtype(str1_inst, str_type)
        self.assert_subtype(str_type, str1_inst)

        # other operand is the same literal
        # "x"  ≲ "x"  -> YES
        # "x"  ≲ "x"? -> YES
        # "x"? ≲ "x"  -> YES
        # "x"? ≲ "x"? -> YES
        self.assert_subtype(str1, str1)
        self.assert_subtype(str1, str1_inst)
        self.assert_subtype(str1_inst, str1)
        self.assert_subtype(str1_inst, str1_inst)

        # other operand is a different literal
        # "x"  ≲ "y"  -> NO
        # "x"  ≲ "y"? -> YES
        # "x"? ≲ "y"  -> NO
        # "x"? ≲ "y"? -> YES
        self.assert_not_subtype(str1, str2)
        self.assert_subtype(str1, str2_inst)
        self.assert_not_subtype(str1_inst, str2)
        self.assert_subtype(str1_inst, str2_inst)

        # check proper subtyping
        # other operand is the fallback type
        # "x"  <: str  -> YES
        # str  <: "x"  -> NO
        # "x"? <: str  -> YES
        # str  <: "x"? -> NO
        self.assert_proper_subtype(str1, str_type)
        self.assert_not_proper_subtype(str_type, str1)
        self.assert_proper_subtype(str1_inst, str_type)
        self.assert_not_proper_subtype(str_type, str1_inst)

        # other operand is the same literal
        # "x"  <: "x"  -> YES
        # "x"  <: "x"? -> YES
        # "x"? <: "x"  -> NO
        # "x"? <: "x"? -> YES
        self.assert_proper_subtype(str1, str1)
        self.assert_proper_subtype(str1, str1_inst)
        self.assert_not_proper_subtype(str1_inst, str1)
        self.assert_proper_subtype(str1_inst, str1_inst)

        # other operand is a different literal
        # "x"  <: "y"  -> NO
        # "x"  <: "y"? -> NO
        # "x"? <: "y"  -> NO
        # "x"? <: "y"? -> NO
        self.assert_not_proper_subtype(str1, str2)
        self.assert_not_proper_subtype(str1, str2_inst)
        self.assert_not_proper_subtype(str1_inst, str2)
        self.assert_not_proper_subtype(str1_inst, str2_inst)

    # IDEA: Maybe add these test cases (they are tested pretty well in type
    #       checker tests already):
    #  * more interface subtyping test cases
    #  * more generic interface subtyping test cases
    #  * type variables
    #  * tuple types
    #  * None type
    #  * any type
    #  * generic function types

    def assert_proper_subtype(self, s: Type, t: Type) -> None:
        assert is_proper_subtype(s, t), f"{s} not proper subtype of {t}"

    def assert_not_proper_subtype(self, s: Type, t: Type) -> None:
        assert not is_proper_subtype(s, t), f"{s} not proper subtype of {t}"

    def assert_subtype(self, s: Type, t: Type) -> None:
        assert is_subtype(s, t), f"{s} not subtype of {t}"

    def assert_not_subtype(self, s: Type, t: Type) -> None:
        assert not is_subtype(s, t), f"{s} subtype of {t}"

    def assert_strict_subtype(self, s: Type, t: Type) -> None:
        self.assert_subtype(s, t)
        self.assert_not_subtype(t, s)

    def assert_equivalent(self, s: Type, t: Type) -> None:
        self.assert_subtype(s, t)
        self.assert_subtype(t, s)

    def assert_unrelated(self, s: Type, t: Type) -> None:
        self.assert_not_subtype(s, t)
        self.assert_not_subtype(t, s)


class RestrictionSuite(Suite):
    # Tests for type restrictions "A - B", i.e. ``T <: A and not T <: B``.

    def setUp(self) -> None:
        self.fx = TypeFixture()

    def assert_restriction(self, s: Type, t: Type, expected: Type) -> None:
        actual = restrict_subtype_away(s, t)
        msg = f"restrict_subtype_away({s}, {t}) == {{}} ({{}} expected)"
        self.assertEqual(actual, expected, msg=msg.format(actual, expected))

    def test_literal(self) -> None:
        str1 = self.fx.lit_str1
        str2 = self.fx.lit_str2
        str1_inst = self.fx.lit_str1_inst
        str2_inst = self.fx.lit_str2_inst
        str_type = self.fx.str_type
        uninhabited = self.fx.uninhabited

        # other operand is the fallback type
        # "x" - str -> Never
        # str - "x" -> str
        # "x"? - str  -> Never
        # str  - "x"? -> Never
        self.assert_restriction(str1, str_type, uninhabited)
        self.assert_restriction(str_type, str1, str_type)
        self.assert_restriction(str1_inst, str_type, uninhabited)
        self.assert_restriction(str_type, str1_inst, uninhabited)

        # other operand is the same literal
        # "x"  - "x"  -> Never
        # "x"  - "x"? -> Never
        # "x"? - "x"  -> Never
        # "x"? - "x"? -> Never
        self.assert_restriction(str1, str1, uninhabited)
        self.assert_restriction(str1, str1_inst, uninhabited)
        self.assert_restriction(str1_inst, str1, uninhabited)
        self.assert_restriction(str1_inst, str1_inst, uninhabited)

        # other operand is a different literal
        # "x"  - "y"  -> "x"
        # "x"  - "y"? -> Never
        # "x"? - "y"  -> "x"?
        # "x"? - "y"? -> Never
        self.assert_restriction(str1, str2, str1)
        self.assert_restriction(str1, str2_inst, uninhabited)
        self.assert_restriction(str1_inst, str2, str1_inst)
        self.assert_restriction(str1_inst, str2_inst, uninhabited)