code: def test_multiindex_assignment_single_dtype(
      self, using_copy_on_write, warn_copy_on_write
  ):
      # GH3777 part 2b
      # single dtype
      arr = np.array([0.0, 1.0])
  
      df = DataFrame(
          np.random.default_rng(2)
          .integers(5, 10, size=9)
          .reshape(3, 3),
          columns=list("abc"),
          index=[[4, 4, 8], [8, 10, 12]],
          dtype=np.int64,
      )
      view = df["c"].iloc[:2].values
  
      # arr can be losslessly cast to int, so this setitem is inplace
      # INFO(CoW-warn) this does not warn because we directly took .values
      # above, so no reference to a pandas object is alive for `view`
      df.loc[4, "c"] = arr
      exp = Series(arr, index=[8, 10], name="c", dtype="int64")
      result = df.loc[4, "c"]
      tm.assert_series_equal(result, exp)
  
      # extra check for inplace-ness
      if not using_copy_on_write:
          tm.assert_numpy_array_equal(view, exp.values)
  
      # arr + 0.5 cannot be cast losslessly to int, so we upcast
      with tm.assert_produces_warning(
          FutureWarning, match="item of incompatible dtype"
      ):
          df.loc[4, "c"] = arr + 0.5
      result = df.loc[4, "c"]
      exp = exp + 0.5
      tm.assert_series_equal(result, exp)
  
      # scalar ok
      with tm.assert_cow_warning(warn_copy_on_write):
          df.loc[4, "c"] = 10
      exp = Series(10, index=[8, 10], name="c", dtype="float64")
      tm.assert_series_equal(df.loc[4, "c"], exp)
  
      # invalid assignments
      msg = "Must have equal len keys and value when setting with an iterable"
      with pytest.raises(ValueError, match=msg):
          df.loc[4, "c"] = [0, 1, 2, 3]
  
      with pytest.raises(ValueError, match=msg):
          df.loc[4, "c"] = [0]
  
      # But with a length-1 listlike column indexer this behaves like
      #  `df.loc[4, "c"] = 0
      with tm.assert_cow_warning(warn_copy_on_write):
          df.loc[4, ["c"]] = [0]
      assert (df.loc[4, "c"] == 0).all()
  
imports: import numpy
  import pytest
  from pandas.errors import SettingWithCopyError
  import pandas
  from pandas import DataFrame, MultiIndex, Series, date_range, isna, notna
  import pandas._testing
label_desc: Use image node_id 8 for calling the TestMultiIndexSetItem obj's underlying member method code with example usage: obj.test_multiindex_assignment_single_dtype(using_copy_on_write, warn_copy_on_write) without return types