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"""Test cases for the constraint solver used in type inference."""
from typing import List, Union, Tuple, Optional
from mypy.test.helpers import Suite, assert_equal
from mypy.constraints import SUPERTYPE_OF, SUBTYPE_OF, Constraint
from mypy.solve import solve_constraints
from mypy.test.typefixture import TypeFixture
from mypy.types import Type, TypeVarType, TypeVarId
class SolveSuite(Suite):
def setUp(self) -> None:
self.fx = TypeFixture()
def test_empty_input(self) -> None:
self.assert_solve([], [], [])
def test_simple_supertype_constraints(self) -> None:
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.a)],
[(self.fx.a, self.fx.o)])
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.a),
self.supc(self.fx.t, self.fx.b)],
[(self.fx.a, self.fx.o)])
def test_simple_subtype_constraints(self) -> None:
self.assert_solve([self.fx.t.id],
[self.subc(self.fx.t, self.fx.a)],
[self.fx.a])
self.assert_solve([self.fx.t.id],
[self.subc(self.fx.t, self.fx.a),
self.subc(self.fx.t, self.fx.b)],
[self.fx.b])
def test_both_kinds_of_constraints(self) -> None:
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.b),
self.subc(self.fx.t, self.fx.a)],
[(self.fx.b, self.fx.a)])
def test_unsatisfiable_constraints(self) -> None:
# The constraints are impossible to satisfy.
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.a),
self.subc(self.fx.t, self.fx.b)],
[None])
def test_exactly_specified_result(self) -> None:
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.b),
self.subc(self.fx.t, self.fx.b)],
[(self.fx.b, self.fx.b)])
def test_multiple_variables(self) -> None:
self.assert_solve([self.fx.t.id, self.fx.s.id],
[self.supc(self.fx.t, self.fx.b),
self.supc(self.fx.s, self.fx.c),
self.subc(self.fx.t, self.fx.a)],
[(self.fx.b, self.fx.a), (self.fx.c, self.fx.o)])
def test_no_constraints_for_var(self) -> None:
self.assert_solve([self.fx.t.id],
[],
[self.fx.uninhabited])
self.assert_solve([self.fx.t.id, self.fx.s.id],
[],
[self.fx.uninhabited, self.fx.uninhabited])
self.assert_solve([self.fx.t.id, self.fx.s.id],
[self.supc(self.fx.s, self.fx.a)],
[self.fx.uninhabited, (self.fx.a, self.fx.o)])
def test_simple_constraints_with_dynamic_type(self) -> None:
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.anyt)],
[(self.fx.anyt, self.fx.anyt)])
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.anyt),
self.supc(self.fx.t, self.fx.anyt)],
[(self.fx.anyt, self.fx.anyt)])
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.anyt),
self.supc(self.fx.t, self.fx.a)],
[(self.fx.anyt, self.fx.anyt)])
self.assert_solve([self.fx.t.id],
[self.subc(self.fx.t, self.fx.anyt)],
[(self.fx.anyt, self.fx.anyt)])
self.assert_solve([self.fx.t.id],
[self.subc(self.fx.t, self.fx.anyt),
self.subc(self.fx.t, self.fx.anyt)],
[(self.fx.anyt, self.fx.anyt)])
# self.assert_solve([self.fx.t.id],
# [self.subc(self.fx.t, self.fx.anyt),
# self.subc(self.fx.t, self.fx.a)],
# [(self.fx.anyt, self.fx.anyt)])
# TODO: figure out what this should be after changes to meet(any, X)
def test_both_normal_and_any_types_in_results(self) -> None:
# If one of the bounds is any, we promote the other bound to
# any as well, since otherwise the type range does not make sense.
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.a),
self.subc(self.fx.t, self.fx.anyt)],
[(self.fx.anyt, self.fx.anyt)])
self.assert_solve([self.fx.t.id],
[self.supc(self.fx.t, self.fx.anyt),
self.subc(self.fx.t, self.fx.a)],
[(self.fx.anyt, self.fx.anyt)])
def assert_solve(self,
vars: List[TypeVarId],
constraints: List[Constraint],
results: List[Union[None, Type, Tuple[Type, Type]]],
) -> None:
res: List[Optional[Type]] = []
for r in results:
if isinstance(r, tuple):
res.append(r[0])
else:
res.append(r)
actual = solve_constraints(vars, constraints)
assert_equal(str(actual), str(res))
def supc(self, type_var: TypeVarType, bound: Type) -> Constraint:
return Constraint(type_var.id, SUPERTYPE_OF, bound)
def subc(self, type_var: TypeVarType, bound: Type) -> Constraint:
return Constraint(type_var.id, SUBTYPE_OF, bound)
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