def test_term_variable_assignment():
a = Term.from_atom_name('a')
b = Term.from_atom_name('b')
eq = Predicate.from_name_arity('=', 2)
X = Term()
assert_true(eq(X, a))
assert_equal(X, a)
assert_false(eq(X, b))
assert_true(eq(Term(), b))
X.put_variable()
assert_true(eq(X, b))
def test_term__and__():
a = Term.from_atom_name('a')
b = Term.from_atom_name('b')
eq = Functor('=', 2)
assert_true((eq(a, a) & eq(b, b))())
assert_false((eq(a, b) & eq(a, a))())
assert_false((eq(a, a) & eq(a, b))())
X = Term()
Y = Term()
assert_true((eq(X, a) & eq(Y, a) & eq(X, Y))())
assert_equal(X, Y)
X.put_variable()
Y.put_variable()
assert_false((eq(X, a) & eq(X, b))())
assert_equal(str(eq(a, a) & eq(a, b)), 'a=a,a=b')
