class_docstr: Tests specific to IntervalIndex with float subtype
class_docstr_tok: ["Tests","specific","to","IntervalIndex","with","float","subtype"]
code: def test_subtype_integer_errors(self):
      # float64 -> uint64 fails with negative values
      index = interval_range(-10.0, 10.0)
      dtype = IntervalDtype("uint64", "right")
      msg = re.escape(
          "Cannot convert interval[float64, right] to interval[uint64, right]; "
          "subtypes are incompatible"
      )
      with pytest.raises(TypeError, match=msg):
          index.astype(dtype)
  
imports: import re
  import numpy
  import pytest
  from pandas.core.dtypes.dtypes import CategoricalDtype, IntervalDtype
  from pandas import CategoricalIndex, Index, IntervalIndex, NaT, Timedelta, Timestamp, interval_range
  import pandas._testing
label_desc: Use image node_id 4 for calling the TestFloatSubtype obj's underlying member method code with example usage: obj.test_subtype_integer_errors() without return types