code: def test_constructor(self, dtype):
      index_cls = Index
  
      # explicit construction
      index = index_cls([1, 2, 3, 4, 5], dtype=dtype)
  
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      expected = np.array([1, 2, 3, 4, 5], dtype=dtype)
      tm.assert_numpy_array_equal(index.values, expected)
  
      index = index_cls(np.array([1, 2, 3, 4, 5]), dtype=dtype)
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      index = index_cls([1.0, 2, 3, 4, 5], dtype=dtype)
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      index = index_cls(np.array([1.0, 2, 3, 4, 5]), dtype=dtype)
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      index = index_cls([1.0, 2, 3, 4, 5], dtype=dtype)
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      index = index_cls(np.array([1.0, 2, 3, 4, 5]), dtype=dtype)
      assert isinstance(index, index_cls)
      assert index.dtype == dtype
  
      # nan handling
      result = index_cls([np.nan, np.nan], dtype=dtype)
      assert pd.isna(result.values).all()
  
      result = index_cls(np.array([np.nan]), dtype=dtype)
      assert pd.isna(result.values).all()
  
imports: import numpy
  import pytest
  import pandas
  from pandas import Index, Series
  import pandas._testing
label_desc: Use image node_id 7 for calling the TestFloatNumericIndex obj's underlying member method code with example usage: obj.test_constructor(dtype) without return types