code: def test_combine_first_convert_datatime_correctly(
      self, data1, data2, data_expected
  ):
      # GH 3593
  
      df1, df2 = DataFrame({"a": data1}), DataFrame({"a": data2})
      result = df1.combine_first(df2)
      expected = DataFrame({"a": data_expected})
      tm.assert_frame_equal(result, expected)
  
imports: from datetime import datetime
  import numpy
  import pytest
  from pandas.core.dtypes.cast import find_common_type
  from pandas.core.dtypes.common import is_dtype_equal
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series
  import pandas._testing
label_desc: Use image node_id 7 for calling the TestDataFrameCombineFirst obj's underlying member method code with example usage: obj.test_combine_first_convert_datatime_correctly(data1, data2, data_expected) without return types