Fix: Boundary Index List Tests now also check `single_link=True`

The error fixed by pystencils!169 (merged) was allowed to pass because the test cases did not check for the single_link=True case.

lbmpy_tests/test_boundary_indexlist_creation.py

-import numpy as np
-
-import pystencils.boundaries.createindexlist as cil
-from lbmpy.stencils import get_stencil
-
-
-def test_equivalence_cython_python_version():
-    if not cil.cython_funcs_available:
-        return
-
-    stencil_2d = get_stencil("D2Q9")
-    stencil_3d = get_stencil("D3Q19")
-
-    for dtype in [int, np.int16, np.uint32]:
-        fluid_mask = dtype(1)
-        mask = dtype(2)
-        flag_field_2d = np.ones([15, 16], dtype=dtype) * fluid_mask
-        flag_field_3d = np.ones([15, 16, 17], dtype=dtype) * fluid_mask
-
-        flag_field_2d[0, :] = mask
-        flag_field_2d[-1, :] = mask
-        flag_field_2d[7, 7] = mask
-
-        flag_field_3d[0, :, :] = mask
-        flag_field_3d[-1, :, :] = mask
-        flag_field_3d[7, 7, 7] = mask
-
-        result_python_2d = cil._create_boundary_neighbor_index_list_python(flag_field_2d, 1, mask, fluid_mask,
-                                                                           stencil_2d, False)
-
-        result_python_3d = cil._create_boundary_neighbor_index_list_python(flag_field_3d, 1, mask, fluid_mask,
-                                                                           stencil_3d, False)
-
-        result_cython_2d = cil.create_boundary_index_list(flag_field_2d, stencil_2d, mask,
-                                                          fluid_mask, 1, True, False)
-        result_cython_3d = cil.create_boundary_index_list(flag_field_3d, stencil_3d, mask,
-                                                          fluid_mask, 1, True, False)
-
-        np.testing.assert_equal(result_python_2d, result_cython_2d)
-        np.testing.assert_equal(result_python_3d, result_cython_3d)
-
-
-def test_equivalence_cell_idx_list_cython_python_version():
-    if not cil.cython_funcs_available:
-        return
-
-    stencil_2d = get_stencil("D2Q9")
-    stencil_3d = get_stencil("D3Q19")
-
-    for dtype in [int, np.int16, np.uint32]:
-        fluid_mask = dtype(1)
-        mask = dtype(2)
-        flag_field_2d = np.ones([15, 16], dtype=dtype) * fluid_mask
-        flag_field_3d = np.ones([15, 16, 17], dtype=dtype) * fluid_mask
-
-        flag_field_2d[0, :] = mask
-        flag_field_2d[-1, :] = mask
-        flag_field_2d[7, 7] = mask
-
-        flag_field_3d[0, :, :] = mask
-        flag_field_3d[-1, :, :] = mask
-        flag_field_3d[7, 7, 7] = mask
-
-        result_python_2d = cil._create_boundary_cell_index_list_python(flag_field_2d, mask, fluid_mask,
-                                                                       stencil_2d, False)
-
-        result_python_3d = cil._create_boundary_cell_index_list_python(flag_field_3d, mask, fluid_mask,
-                                                                       stencil_3d, False)
-
-        result_cython_2d = cil.create_boundary_index_list(flag_field_2d, stencil_2d, mask, fluid_mask, None,
-                                                          False, False)
-        result_cython_3d = cil.create_boundary_index_list(flag_field_3d, stencil_3d, mask, fluid_mask, None,
-                                                          False, False)
-
-        np.testing.assert_equal(result_python_2d, result_cython_2d)
-        np.testing.assert_equal(result_python_3d, result_cython_3d)