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ljkiwi/kiwi/py/tests/test_expression.py

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Python

# --------------------------------------------------------------------------------------
# Copyright (c) 2014-2021, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
# --------------------------------------------------------------------------------------
import gc
import math
import operator
import sys
from typing import Tuple
import pytest
from kiwisolver import Constraint, Expression, Term, Variable, strength
def test_expression_creation() -> None:
"""Test the Term constructor."""
v = Variable("foo")
v2 = Variable("bar")
v3 = Variable("aux")
e1 = Expression((v * 1, v2 * 2, v3 * 3))
e2 = Expression((v * 1, v2 * 2, v3 * 3), 10)
for e, val in ((e1, 0), (e2, 10)):
t = e.terms()
assert (
len(t) == 3
and t[0].variable() is v
and t[0].coefficient() == 1
and t[1].variable() is v2
and t[1].coefficient() == 2
and t[2].variable() is v3
and t[2].coefficient() == 3
)
assert e.constant() == val
assert str(e2) == "1 * foo + 2 * bar + 3 * aux + 10"
with pytest.raises(TypeError) as excinfo:
Expression((1, v2 * 2, v3 * 3)) # type: ignore
assert "Term" in excinfo.exconly()
# ensure we test garbage collection.
del e2
gc.collect()
@pytest.fixture()
def expressions():
"""Build expressions, terms and variables to test operations."""
v = Variable("foo")
v2 = Variable("bar")
t = Term(v, 10)
t2 = Term(v2)
e = t + 5
e2 = v2 - 10
return e, e2, t, t2, v, v2
def test_expression_neg(
expressions: Tuple[Expression, Expression, Term, Term, Variable, Variable],
):
"""Test neg on an expression."""
e, _, _, _, v, _ = expressions
neg = -e
assert isinstance(neg, Expression)
neg_t = neg.terms()
assert (
len(neg_t) == 1
and neg_t[0].variable() is v
and neg_t[0].coefficient() == -10
and neg.constant() == -5
)
def test_expression_mul(
expressions: Tuple[Expression, Expression, Term, Term, Variable, Variable],
):
"""Test expresion multiplication."""
e, _, _, _, v, _ = expressions
for mul in (e * 2.0, 2.0 * e):
assert isinstance(mul, Expression)
mul_t = mul.terms()
assert (
len(mul_t) == 1
and mul_t[0].variable() is v
and mul_t[0].coefficient() == 20
and mul.constant() == 10
)
with pytest.raises(TypeError):
e * v # type: ignore
def test_expression_div(
expressions: Tuple[Expression, Expression, Term, Term, Variable, Variable],
):
"""Test expression divisions."""
e, _, _, _, v, v2 = expressions
div = e / 2
assert isinstance(div, Expression)
div_t = div.terms()
assert (
len(div_t) == 1
and div_t[0].variable() is v
and div_t[0].coefficient() == 5
and div.constant() == 2.5
)
with pytest.raises(TypeError):
e / v2 # type: ignore
with pytest.raises(ZeroDivisionError):
e / 0
def test_expression_addition(
expressions: Tuple[Expression, Expression, Term, Term, Variable, Variable],
):
"""Test expressions additions."""
e, e2, _, t2, v, v2 = expressions
for add in (e + 2, 2.0 + e):
assert isinstance(add, Expression)
assert add.constant() == 7
terms = add.terms()
assert (
len(terms) == 1
and terms[0].variable() is v
and terms[0].coefficient() == 10
)
add2 = e + v2
assert isinstance(add2, Expression)
assert add2.constant() == 5
terms = add2.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == 10
and terms[1].variable() is v2
and terms[1].coefficient() == 1
)
add3 = e + t2
assert isinstance(add3, Expression)
assert add3.constant() == 5
terms = add3.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == 10
and terms[1].variable() is v2
and terms[1].coefficient() == 1
)
add4 = e + e2
assert isinstance(add4, Expression)
assert add4.constant() == -5
terms = add4.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == 10
and terms[1].variable() is v2
and terms[1].coefficient() == 1
)
def test_expressions_substraction(
expressions: Tuple[Expression, Expression, Term, Term, Variable, Variable],
):
"""Test expression substraction."""
e, e2, _, t2, v, v2 = expressions
for sub, diff in zip((e - 2, 2.0 - e), (3, -3)):
assert isinstance(sub, Expression)
assert sub.constant() == diff
terms = sub.terms()
assert (
len(terms) == 1
and terms[0].variable() is v
and terms[0].coefficient() == math.copysign(10, diff)
)
for sub2, diff in zip((e - v2, v2 - e), (5, -5)):
assert isinstance(sub2, Expression)
assert sub2.constant() == diff
terms = sub2.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == math.copysign(10, diff)
and terms[1].variable() is v2
and terms[1].coefficient() == -math.copysign(1, diff)
)
for sub3, diff in zip((e - t2, t2 - e), (5, -5)):
assert isinstance(sub3, Expression)
assert sub3.constant() == diff
terms = sub3.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == math.copysign(10, diff)
and terms[1].variable() is v2
and terms[1].coefficient() == -math.copysign(1, diff)
)
sub4 = e - e2
assert isinstance(sub3, Expression)
assert sub4.constant() == 15
terms = sub4.terms()
assert (
len(terms) == 2
and terms[0].variable() is v
and terms[0].coefficient() == 10
and terms[1].variable() is v2
and terms[1].coefficient() == -1
)
@pytest.mark.parametrize(
"op, symbol",
[
(operator.le, "<="),
(operator.eq, "=="),
(operator.ge, ">="),
(operator.lt, None),
(operator.ne, None),
(operator.gt, None),
],
)
def test_expression_rich_compare_operations(op, symbol) -> None:
"""Test using comparison on variables."""
v1 = Variable("foo")
v2 = Variable("bar")
t1 = Term(v1, 10)
e1 = t1 + 5
e2 = v2 - 10
if symbol is not None:
c = op(e1, e2)
assert isinstance(c, Constraint)
e = c.expression()
t = e.terms()
assert len(t) == 2
if t[0].variable() is not v1:
t = (t[1], t[0])
assert (
t[0].variable() is v1
and t[0].coefficient() == 10
and t[1].variable() is v2
and t[1].coefficient() == -1
)
assert e.constant() == 15
assert c.op() == symbol and c.strength() == strength.required
else:
with pytest.raises(TypeError) as excinfo:
op(e1, e2)
if "PyPy" in sys.version:
assert "Expression" in excinfo.exconly()
else:
assert "kiwisolver.Expression" in excinfo.exconly()