Unit-testing with dependencies between tests

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How do you do unit testing when you have

  • some general unit tests
  • more sophisticated tests checking edge cases, depending on the general ones

To give an example, imagine testing a CSV-reader (I just made up a notation for demonstration),

def test_readCsv(): ...

@dependsOn(test_readCsv)
def test_readCsv_duplicateColumnName(): ...

@dependsOn(test_readCsv)
def test_readCsv_unicodeColumnName(): ...

I expect sub-tests to be run only if their parent test succeeds. The reason behind this is that running these tests takes time. Many failure reports that go back to a single reason wouldn't be informative, either. Of course, I could shoehorn all edge-cases into the main test, but I wonder if there is a more structured way to do this.

I've found these related but different questions,

UPDATE:

I've found TestNG which has great built-in support for test dependencies. You can write tests like this,

@Test{dependsOnMethods = ("test_readCsv"))
public void test_readCsv_duplicateColumnName() {
   ...
}
code-organization unit-testing python
6 Answers

You may want use pytest-dependency. According to theirs documentation code looks elegant:

import pytest

@pytest.mark.dependency()
@pytest.mark.xfail(reason="deliberate fail")
def test_a():
    assert False

@pytest.mark.dependency()
def test_b():
    pass

@pytest.mark.dependency(depends=["test_a"])
def test_c():
    pass

@pytest.mark.dependency(depends=["test_b"])
def test_d():
    pass

@pytest.mark.dependency(depends=["test_b", "test_c"])
def test_e():
    pass

Please note, it is plugin for pytest, not unittest which is part of python itself. So, you need 2 more dependencies (f.e. add into requirements.txt):

pytest==5.1.1
pytest-dependency==0.4.0
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