def METHOD_NAME(self):
    """Create a test HDF5 file."""
    import h5py
    h = h5py.File('test.h5', 'w')
    # Create Group
    g1 = h.create_group('test_group')
    # Add datasets
    ds1_f = g1.create_dataset('ds1_f',
                              shape=(10, 100),
                              dtype=np.float32,
                              data=np.arange(10. * 100).reshape((10, 100)))
    ds1_i = g1.create_dataset('ds1_i',
                              shape=(10, 100),
                              dtype=np.int32,
                              data=np.arange(10 * 100).reshape((10, 100)))
    ds2_f = h.create_dataset('ds2_f',
                             shape=(10, 100),
                             dtype=np.float32,
                             data=np.arange(10. * 100).reshape((10, 100)))
    ds2_i = h.create_dataset('ds2_i',
                             shape=(10, 100),
                             dtype=np.int32,
                             data=np.arange(10 * 100).reshape((10, 100)))
    # Add attributes
    # shows up as a scalar array of bytes (shape=(), size=1)
    h.attrs['test_attr_str'] = 'test_string'
    h.attrs['test_attr_byte'] = b'test_byte'
    h.attrs['test_attr_int'] = 0
    h.attrs['test_attr_float'] = 1.2
    # shows up as a numpy bytes object
    h.attrs['test_attr_str_arr'] = np.array(b"test_string2")
    g1.attrs['test_attr_str'] = 'test_string'
    g1.attrs['test_attr_byte'] = b'test_byte'
    g1.attrs['test_attr_int'] = 0
    g1.attrs['test_attr_float'] = 1.2
    for d in [ds1_f, ds1_i, ds2_f, ds2_i]:
        d.attrs['test_attr_str'] = 'test_string'
        d.attrs['test_attr_byte'] = b'test_byte'
        d.attrs['test_attr_int'] = 0
        d.attrs['test_attr_float'] = 1.2
        d.attrs['test_ref'] = d.ref
    self.var_attrs = list(d.attrs.keys())
    h.close()