code: def test_ewm_corr_cov(name):
      A = Series(
          np.random.default_rng(2).standard_normal(50), index=range(50)
      )
      B = A[2:] + np.random.default_rng(2).standard_normal(48)
  
      A[:10] = np.nan
      B.iloc[-10:] = np.nan
  
      result = getattr(A.ewm(com=20, min_periods=5), name)(B)
      assert np.isnan(result.values[:14]).all()
      assert not np.isnan(result.values[14:]).any()
  
imports: import numpy
  import pytest
  from pandas import DataFrame, DatetimeIndex, Series, date_range
  import pandas._testing
label_desc: Use image node_id 25 for calling a global function with example usage: test_ewm_corr_cov(name) without return types