Re: Failed to unit test PyFlink UDF

Posted by Dian Fu on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Failed-to-unit-test-PyFlink-UDF-tp42450p42461.html

Hi Yik San,

This field isn't expected to be exposed to users and so I'm not convinced that we should add such an interface/method in Flink.

Regards,
Dian

On Tue, Mar 23, 2021 at 2:04 PM Yik San Chan <[hidden email]> wrote:

Hi Dian,

The ._func method seems to be internal only. Maybe we can add some public-facing method to make it more intuitive for use in unit test? What do you think?

Best,

Yik San

On Tue, Mar 23, 2021 at 2:02 PM Yik San Chan <[hidden email]> wrote:

Hi Dian,

Thanks! It solves my problem.

Best,

Yik San

On Tue, Mar 23, 2021 at 1:29 PM Dian Fu <[hidden email]> wrote:

H Yik San,

As the udf `add` is decorated with `@udf` decorator, it is no longer a simple Python function if you reference `add`. If you execute `print(type(add(1, 1)))`, you will see the output is something like "<class 'pyflink.table.expression.Expression'>".

You could try the following code: assert add._func(1, 1) == 3

add._func returns the original Python function.

Regards,
Dian

On Tue, Mar 23, 2021 at 10:56 AM Yik San Chan <[hidden email]> wrote:

(This question is cross-posted on StackOverflow https://stackoverflow.com/questions/66756612/failed-to-unit-test-pyflink-udf)

I am using PyFlink and I want to unit test my UDF written in Python.

To test the simple udf below:

```python
# tasks/helloworld/udf.py
from pyflink.table import DataTypes
from pyflink.table.udf import udf

@udf(input_types=[DataTypes.INT(), DataTypes.INT()], result_type=DataTypes.BIGINT())
def add(i, j):
    return i + j
```

I create a test file that should fail:
```python
from tasks.helloworld.udf import add

def test_add():
    assert add(1,1) == 3
```

Sadly, it passes if I run `pytest`:
```
> pytest
=========================================================================================== test session starts ============================================================================================
platform darwin -- Python 3.7.10, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: /Users/chenyisheng/source/yiksanchan/pytest-flink
collected 1 item

tests/test_helloworld.py .                                                                                                                                                                           [100%]

============================================================================================= warnings summary =============================================================================================
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
  /usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working
    from collections import (

../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/pyflink/table/udf.py:291
  /usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/pyflink/table/udf.py:291: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working
    if not isinstance(input_types, collections.Iterable) \

-- Docs: https://docs.pytest.org/en/stable/warnings.html
====================================================================================== 1 passed, 6 warnings in 0.98s =======================================================================================
```

However, the test will fail as expected if I remove the `@udf(input_types=[...], result_type=...)` annotation:
```
> pytest
=========================================================================================== test session starts ============================================================================================
platform darwin -- Python 3.7.10, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: /Users/chenyisheng/source/yiksanchan/pytest-flink
collected 1 item

tests/test_helloworld.py F                                                                                                                                                                           [100%]

================================================================================================= FAILURES =================================================================================================
_________________________________________________________________________________________________ test_add _________________________________________________________________________________________________

    def test_add():
>       assert add(1,1) == 3
E       assert 2 == 3
E        +  where 2 = add(1, 1)

tests/test_helloworld.py:4: AssertionError
============================================================================================= warnings summary =============================================================================================
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
../../../../../usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13
  /usr/local/anaconda3/envs/pyflink-quickstart/lib/python3.7/site-packages/py4j/java_collections.py:13: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated since Python 3.3,and in 3.9 it will stop working
    from collections import (

-- Docs: https://docs.pytest.org/en/stable/warnings.html
========================================================================================= short test summary info ==========================================================================================
FAILED tests/test_helloworld.py::test_add - assert 2 == 3
====================================================================================== 1 failed, 5 warnings in 0.17s =======================================================================================
```

The full example can be found https://github.com/YikSanChan/how-to-pytest-flink.

Best,

Yik San