old_contents: import pytest  # type: ignore
  
  from ppb_vector import Vector
  
  
  @pytest.mark.parametrize(
      "x, y, expected",
      [(6,   8, 10),
       (8,   6, 10),
       (0,   0, 0),
       (-6, -8, 10),
       (1,   2, 2.23606797749979)],
  )
  def test_length(x, y, expected):
      vector = Vector(x, y)
      assert vector.length == expected
  
new_contents: from math import sqrt
  
  import pytest  # type: ignore
  from hypothesis import given
  
  from ppb_vector import Vector
  from utils import isclose, vectors
  
  
  @pytest.mark.parametrize(
      "x, y, expected",
      [(6,   8, 10),
       (8,   6, 10),
       (0,   0, 0),
       (-6, -8, 10),
       (1,   2, 2.23606797749979)],
  )
  def test_length(x, y, expected):
      vector = Vector(x, y)
      assert vector.length == expected
  
  
  @given(v=vectors())
  def test_length_dot(v: Vector):
      """Test that |v| ≃ √v²."""
      assert isclose(v.length, sqrt(v * v))
  
subject: Add comparison to (the square root of) the dot product