code: def test_cases(self):
      # Basic cases
      for (
          series,
          diff,
          seas_diff,
          seasonal_periods,
          result,
      ) in self.cases:
          seasonal_diff = seas_diff
  
          # Test numpy array
          x = tools.diff(series, diff, seasonal_diff, seasonal_periods)
          assert_almost_equal(x, result)
  
          # Test as Pandas Series
          series = pd.Series(series)
  
          # Rewrite to test as n-dimensional array
          series = np.c_[series, series]
          result = np.c_[result, result]
  
          # Test Numpy array
          x = tools.diff(series, diff, seasonal_diff, seasonal_periods)
          assert_almost_equal(x, result)
  
          # Test as Pandas DataFrame
          series = pd.DataFrame(series)
          x = tools.diff(series, diff, seasonal_diff, seasonal_periods)
          assert_almost_equal(x, result)
  
imports: import pytest
  import numpy
  from numpy.testing import assert_allclose, assert_equal, assert_array_less, assert_array_equal, assert_almost_equal
  import pandas
  from scipy.linalg import solve_discrete_lyapunov
  from statsmodels.tsa.statespace import tools
  from statsmodels.tsa.stattools import acovf
label_desc: Use image node_id 1 for calling the TestDiff obj's underlying member method code with example usage: obj.test_cases() without return types