Long parametrized test_input on Windows: ValueError: the environment variable is longer than 32767 characters

• a detailed description of the bug or suggestion
• output of pip list from the virtual environment you are using

Package        Version    
-------------- -----------
atomicwrites   1.3.0      
attrs          19.3.0     
colorama       0.4.3      
more-itertools 8.2.0      
packaging      20.3       
pip            20.0.2     
pluggy         0.13.1     
py             1.8.1      
pyparsing      2.4.6      
pytest         5.3.5      
setuptools     41.2.0     
six            1.14.0     
ujson          1.36.dev102
wcwidth        0.1.8  

• pytest and operating system versions pytest 5.3.5, Windows Server 2019 on GitHub Actions Python 3.5-3.8
• minimal example if possible

Include long test input in a parametrize test:

@pytest.mark.parametrize(
    "test_input",
    [
        "1",
        "2",
        "[" * (1024 * 1024),
        "{" * (1024 * 1024),
    ],
)
def test_long_input(test_input):
    # Do something with test_input
    pass

Expected

Tests pass

Actual

Tests fail with ValueError: the environment variable is longer than 32767 characters:

2020-03-08T21:44:22.8972828Z key = 'PYTEST_CURRENT_TEST'
2020-03-08T21:44:22.8973045Z value = 'tests/test_ujson.py::test_long_input[{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{...{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{] (teardown)'
2020-03-08T21:44:22.8973138Z 
2020-03-08T21:44:22.8973265Z     def __setitem__(self, key, value):
2020-03-08T21:44:22.8973624Z         key = self.encodekey(key)
2020-03-08T21:44:22.8973756Z         value = self.encodevalue(value)
2020-03-08T21:44:22.8973879Z >       self.putenv(key, value)
2020-03-08T21:44:22.8974020Z E       ValueError: the environment variable is longer than 32767 characters
2020-03-08T21:44:22.8974117Z 
2020-03-08T21:44:22.8974254Z c:\hostedtoolcache\windows\python\3.8.2\x64\lib\os.py:681: ValueError
2020-03-08T21:44:22.8974408Z ======================== 138 passed, 4 errors in 2.66s ========================
2020-03-08T21:44:22.9037130Z ##[error]Process completed with exit code 1.

https://github.com/hugovk/ultrajson/runs/493853892?check_suite_focus=true

Passes on Ubuntu 16.04, 18.04, macOS Catalina 10.15 with Python 2.7, 3.5-3.8, but for all operating systems the test name is also really long because it includes the parameterised values, which clutters the logs.

Can be worked around by splitting the long test input into its own method:

@pytest.mark.parametrize(
    "test_input",
    [
        "1",
        "2",
    ],
)
def test_long_input(test_input):
    # Do something with test_input
    pass

@pytest.mark.parametrize(
    "test_input",
    [
        "[",
        "{",
    ],
)
def test_long_input(test_input):
    # Do something with test_input * (1024 * 1024), instead of test_input
    pass

• https://github.com/hugovk/ultrajson/commit/f9a4f42efe3d719ec3aa15f63c07852e632f0b40

[The-Compiler]

(Although there are 30 params in the real test, so I’d opt for the method splitting workaround in this case.)

Note that you can pass a function to ids instead (docs). Thus, you could do something like ids=lambda s: s[:10] (assuming that your IDs are still unique after that).

[hugovk]

Thanks, passing ids=... works around the env issue too:

@pytest.mark.parametrize(
    "test_input",
    [
        "1",
        "2",
        "[" * (1024 * 1024),
        "{" * (1024 * 1024),
    ],
    ids=["a", "b", "c", "d"]
)
def test_long_input(test_input):
    pass

(Although there are 30 params in the real test, so I’d opt for the method splitting workaround in this case.)