trs/tests/test_rules_integrals.py

from src.rules.integrals import indef, choose_constant, solve_integral, \
        match_solve_indef, solve_indef, match_integrate_variable_power, \
        integrate_variable_root, integrate_variable_exponent, \
        match_constant_integral, constant_integral, \
        match_factor_out_constant, factor_out_constant, \
        match_division_integral, division_integral, extend_division_integral, \
        match_function_integral, logarithm_integral, sinus_integral, \
        cosinus_integral
from src.node import Scope
from src.possibilities import Possibility as P
from tests.rulestestcase import RulesTestCase, tree


class TestRulesIntegrals(RulesTestCase):

    def test_choose_constant(self):
        a, b, c = tree('a, b, c')
        self.assertEqual(choose_constant(tree('int x ^ n')), c)
        self.assertEqual(choose_constant(tree('int x ^ c')), a)
        self.assertEqual(choose_constant(tree('int a ^ c da')), b)

    def test_match_solve_indef(self):
        root = tree('[x ^ 2]_a^b')
        self.assertEqualPos(match_solve_indef(root), [P(root, solve_indef)])

    def test_solve_integral(self):
        root, F, Fc = tree('int x ^ 2 dx, 1 / 3 x ^ 3, 1 / 3 x ^ 3 + c')
        self.assertEqual(solve_integral(root, F), Fc)
        x2, x, a, b = root = tree('int_a^b x ^ 2 dx')
        self.assertEqual(solve_integral(root, F), indef(Fc, a, b))

    def test_solve_integral_skip_indef(self):
        root, x, c, l1 = tree('int_a^b y ^ x dy, x, c, 1')
        F = tree('1 / (x + 1)y ^ (x + 1)')
        y, a, b = root[1:4]
        Fx = lambda y: l1 / (x + 1) * y ** (x + 1) + c
        self.assertEqual(solve_integral(root, F), Fx(b) - Fx(a))

    def test_solve_indef(self):
        root, expect = tree('[x ^ 2]_a^b, b2 - a2')
        self.assertEqual(solve_indef(root, ()), expect)

    def test_match_integrate_variable_power(self):
        for root in tree('int x ^ n, int x ^ n'):
            self.assertEqualPos(match_integrate_variable_power(root),
                    [P(root, integrate_variable_root)])

        for root in tree('int g ^ x, int g ^ x'):
            self.assertEqualPos(match_integrate_variable_power(root),
                    [P(root, integrate_variable_exponent)])

    def test_integrate_variable_root(self):
        root, expect = tree('int x ^ n, x ^ (n + 1) / (n + 1) + c')
        self.assertEqual(integrate_variable_root(root, ()), expect)

    def test_integrate_variable_exponent(self):
        root, expect = tree('int g ^ x, g ^ x / ln(g) + c')
        self.assertEqual(integrate_variable_exponent(root, ()), expect)

    def test_match_constant_integral(self):
        root0, root1 = tree('int 2, int c dx')
        self.assertEqualPos(match_constant_integral(root0),
                [P(root0, constant_integral)])
        self.assertEqualPos(match_constant_integral(root1),
                [P(root1, constant_integral)])

    def test_constant_integral(self):
        root, expect = tree('int 2, 2x + c')
        self.assertEqual(constant_integral(root, ()), expect)

        root, expect = tree('int_0^4 2, [2x + c]_0^4')
        self.assertEqual(constant_integral(root, ()), expect)

    def test_match_factor_out_constant(self):
        root, c, cx = tree('int cx dx, c, cx')
        self.assertEqualPos(match_factor_out_constant(root),
                [P(root, factor_out_constant, (Scope(cx), c))])

    def test_factor_out_constant(self):
        root, expect = tree('int cx2 dx, c int x2 dx')
        c, x2 = cx2 = root[0]
        self.assertEqual(factor_out_constant(root, (Scope(cx2), c)), expect)

    def test_match_division_integral(self):
        root0, root1 = tree('int 1 / x, int 2 / x')
        self.assertEqualPos(match_division_integral(root0),
                [P(root0, division_integral)])
        self.assertEqualPos(match_division_integral(root1),
                [P(root1, extend_division_integral)])

    def test_division_integral(self):
        root, expect = tree('int 1 / x dx, ln|x| + c')
        self.assertEqual(division_integral(root, ()), expect)

    def test_extend_division_integral(self):
        root, expect = tree('int a / x dx, int a(1 / x) dx')
        self.assertEqual(extend_division_integral(root, ()), expect)

    def test_match_division_integral_chain(self):
        self.assertRewrite([
            'int a / x',
            'int a(1 / x) dx',
            # FIXME: 'a int 1 / x dx',  # fix with strategy
            # FIXME: 'aln|x| + c',
        ])

    def test_match_function_integral(self):
        root0, root1, root2 = tree('int ln x, int sin x, int cos x')
        self.assertEqualPos(match_function_integral(root0),
                [P(root0, logarithm_integral)])
        self.assertEqualPos(match_function_integral(root1),
                [P(root1, sinus_integral)])
        self.assertEqualPos(match_function_integral(root2),
                [P(root2, cosinus_integral)])

    def test_logarithm_integral(self):
        root, expect = tree('int ln x, (xlnx - x) / ln e + c')
        self.assertEqual(logarithm_integral(root, ()), expect)

    def test_sinus_integral(self):
        root, expect = tree('int sin x, -cos x + c')
        self.assertEqual(sinus_integral(root, ()), expect)

    def test_cosinus_integral(self):
        root, expect = tree('int cos x, sin x + c')
        self.assertEqual(cosinus_integral(root, ()), expect)