# Names

Dependencies of tests are referenced by name. The default name is the node id assigned to the test by pytest. This default may be overridden by an explicit name argument to the `pytest.mark.dependency()` marker. The references also depend on the scope.

## Node ids

The node ids in pytest are built of several components, separated by a double colon “::”. For test functions, these components are the relative path of the test module and the name of the function. In the case of a method of a test class the components are the module path, the name of the class, and the name of the method. If the function or method is parameterized, the parameter values, separated by minus “-“, in square brackets “[]” are appended to the node id. The representation of the parameter values in the node id may be overridden using the ids argument to the pytest.mark.parametrize() marker.

One may check the node ids of all tests calling pytest with the –verbose command line option. As an example, consider the following test module:

    import random
    import pytest

    def test_a():
        pass

    @pytest.mark.parametrize("i,b", [
        (7, True),
        (0, False),
        pytest.param(-1, False, marks=pytest.mark.xfail(reason="nonsense"))
    ])
    def test_b(i, b):
        assert bool(i) == b

    ordered = list(range(10))
    unordered = random.sample(ordered, k=len(ordered))

    class TestClass:

        def test_c(self):
            pass

        @pytest.mark.parametrize("l,ll", [(ordered, 10), (unordered, 10)],
                                 ids=["order", "disorder"])
        def test_d(self, l, ll):
            assert len(l) == ll

If this module is stored as tests/test_nodeid.py, the output will look like:

    $ pytest --verbose
    ============================= test session starts ==============================
    platform linux -- Python 3.8.1, pytest-5.3.4, py-1.8.1, pluggy-0.13.1 -- /usr/bin/python3
    cachedir: .pytest_cache
    rootdir: /home/user
    plugins: dependency-0.4.0
    collected 7 items

    tests/test_nodeid.py::test_a PASSED                                      [ 14%]
    tests/test_nodeid.py::test_b[7-True] PASSED                              [ 28%]
    tests/test_nodeid.py::test_b[0-False] PASSED                             [ 42%]
    tests/test_nodeid.py::test_b[-1-False] XFAIL                             [ 57%]
    tests/test_nodeid.py::TestClass::test_c PASSED                           [ 71%]
    tests/test_nodeid.py::TestClass::test_d[order] PASSED                    [ 85%]
    tests/test_nodeid.py::TestClass::test_d[disorder] PASSED                 [100%]

    ========================= 6 passed, 1 xfailed in 0.08s =========================

Note

Old versions of pytest used to include an extra “()” component to the node ids of methods of test classes. This has been removed in pytest 4.0.0. pytest-dependency strips this if present. Thus, when referencing dependencies, the new style node ids as described above may (and must) be used, regardless of the pytest version.

## References and scope

When referencing dependencies of tests, the names to be used in the depends argument to the `pytest.mark.dependency()` marker or the other argument to the `pytest_dependency.depends()` function depend on the scope as follows:

session

  The full node id must be used.

package

  The full node id must be used.

module

  The node id with the leading module path including the “::” separator removed must be used.

class

  The node id with the module path and the class name including the “::” separator removed must be used.

That is, in the example above, when referencing test_a as a dependency, it must be referenced as tests/test_nodeid.py::test_a in session scope and as test_a in module scope. When referencing the first invocation of test_d as a dependency, it must be referenced as tests/test_nodeid.py::TestClass::test_d[order] in session scope, as TestClass::test_d[order] in module scope, and as test_d[order] in class scope.

If the name of the dependency has been set with an explicit name argument to the `pytest.mark.dependency()` marker, this name must always be used as is, regardless of the scope.

Note

The module path in the node id is the path relative to the current working directory. This depends on the invocation of pytest. In the example above, if you change into the tests directory before invoking pytest, the module path in the node ids will be test_nodeid.py. If you use references in session scope, you’ll need to make sure pytest is always invoked from the same working directory.