add unit test for normal_dot_vec

[GreatV]

PR types

Others

PR changes

Others

Describe

add unit test for normal_dot_vec.py

pytest --cov=./ppsci/equation/pde test/equation/test_normal_dot_vec.py
========================================================= test session starts ==========================================================
platform linux -- Python 3.10.6, pytest-7.3.2, pluggy-1.0.0
rootdir: /home/greatx/repos/PaddleScience
plugins: anyio-3.7.0, cov-4.1.0
collected 1 item                                                                                                                       

test/equation/test_normal_dot_vec.py .                                                                                           [100%]

---------- coverage: platform linux, python 3.10.6-final-0 -----------
Name                                      Stmts   Miss  Cover
-------------------------------------------------------------
ppsci/equation/pde/__init__.py                9      0   100%
ppsci/equation/pde/base.py                   26      7    73%
ppsci/equation/pde/biharmonic.py             17     13    24%
ppsci/equation/pde/laplace.py                15     11    27%
ppsci/equation/pde/linear_elasticity.py     155    149     4%
ppsci/equation/pde/navier_stokes.py          60     53    12%
ppsci/equation/pde/normal_dot_vec.py         13      0   100%
ppsci/equation/pde/poisson.py                13      9    31%
ppsci/equation/pde/viv.py                    20     13    35%
-------------------------------------------------------------
TOTAL                                       328    255    22%


========================================================== 1 passed in 4.36s ===========================================================

[paddle-bot]

Thanks for your contribution!

[HydrogenSulfate]

LGTM