import pytest
from collatz import CollatzCalculator

def test_calculate_steps_for_1():
    calc = CollatzCalculator()
    assert calc.calculate_steps(1) == 0

def test_calculate_steps_for_2():
    calc = CollatzCalculator()
    assert calc.calculate_steps(2) == 2  # 2 -> 1 (even), returns 2 steps

def test_calculate_steps_for_3():
    calc = CollatzCalculator()
    assert calc.calculate_steps(3) == 8  # 3 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1

def test_calculate_steps_for_6():
    calc = CollatzCalculator()
    assert calc.calculate_steps(6) == 9  # 6 -> 3 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1

def test_calculate_steps_for_large_number():
    calc = CollatzCalculator()
    assert calc.calculate_steps(27) == 112

def test_calculate_steps_for_zero_and_negative():
    calc = CollatzCalculator()
    assert calc.calculate_steps(0) == 0
    assert calc.calculate_steps(-5) == 0