class_docstr: Base class for ExtensionDtype classes
class_docstr_tok: ["Base","class","for","ExtensionDtype","classes"]
code: def test_get_common_dtype(self, dtype):
      # in practice we will not typically call this with a 1-length list
      # (we shortcut to just use that dtype as the common dtype), but
      # still testing as good practice to have this working (and it is the
      # only case we can test in general)
      assert dtype._get_common_dtype([dtype]) == dtype
  
imports: import numpy
  import pytest
  import pandas
  import pandas._testing
  from pandas.api.types import infer_dtype, is_object_dtype, is_string_dtype
label_desc: Use image node_id 20 for calling the BaseDtypeTests obj's underlying member method code with example usage: obj.test_get_common_dtype(dtype) without return types