text: from mypy.test.helpers import Suite, skip
  from mypy.nodes import CONTRAVARIANT, INVARIANT, COVARIANT
  from mypy.subtypes import is_subtype
  from mypy.test.typefixture import TypeFixture, InterfaceTypeFixture
  from mypy.types import Type
  
  
  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)
  
      @skip
      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, self.fx.nonet),
                                     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))
  
      # 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_subtype(self, s: Type, t: Type) -> None:
          assert is_subtype(s, t), '{} not subtype of {}'.format(s, t)
  
      def assert_not_subtype(self, s: Type, t: Type) -> None:
          assert not is_subtype(s, t), '{} subtype of {}'.format(s, 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)
  