def test_formula_object_copy():
"""Compare Formula objects."""
formula = Formula("2*log(1)", 99)
formula2 = formula.copy()
assert formula2 != formula
assert formula2 is not formula
assert formula2.expression == formula.expression
assert formula2.precision == formula.precision
assert formula2.get() == formula.get()
formula.expression = "1"
assert formula.get() == "1"
assert formula2.get() != formula.get()
