code: def test_linear_regression(self):
      x = Series([1, 2, 3, 4, 5])
      y = Series([1.8, 2.1, 2.7, 3.2, 4])
  
      result = self.utils.linear_regression(x, y)
      self.assertIsInstance(result, dict)
      self.assertIsInstance(result["a"], float)
      self.assertIsInstance(result["b"], float)
      self.assertIsInstance(result["r"], float)
      self.assertIsInstance(result["t"], float)
      self.assertIsInstance(result["line"], Series)
  
imports: from .config import sample_data
  from .context import pandas_ta
  from unittest import skip, TestCase
  from unittest.mock import patch
  import numpy
  import numpy.testing
  from pandas import DataFrame, Series
  from pandas.api.types import is_datetime64_ns_dtype, is_datetime64tz_dtype
label_desc: Use image node_id 22 for calling the TestUtilities obj's underlying member method code with example usage: obj.test_linear_regression() without return types