Remove fixture name uniqueness constraint

[darrenburns]

When fixtures are collected, they're stored inside a FixtureRegistry. The FixtureRegistry essentially just wraps a dictionary which maps fixture names to Fixture objects (Dict[str, Fixture]).

ward/ward/fixtures.py

Line 71 in 795b918

class FixtureRegistry:

The name of a Fixture, and therefore the key used to access it from the FixtureRegistry, is just the name of the function. For example, the fixture below has the name bob:

@fixture
def bob():
    return "bob"

A side effect of just using the function name to identify a fixture is that if two fixtures of the same name are collected in a single ward run, the run will fail even if the fixtures are defined in different files (specifically we raise a CollectionError). If we didn't fail the run, the key in the wrapped dict could get overwritten, and we might inject the wrong fixture. Here's where the failure happens:

ward/ward/fixtures.py

Line 84 in 795b918

raise CollectionError(f"Multiple fixtures named '{func.__name__}'.")

• How should we store fixtures in the registry such that there can be multiple fixtures of the same name across different files?
• When a test later goes to use a fixture, how will it know which one fixture to get from the registry?
• Should it only return fixtures that are in sibling modules?
• How can we make it prioritise fixtures in the same file?
• Should a warning be printed if a test is unsure which fixture to use?

These are just some of the questions raised by this issue, which will require lots of thought on the most sensible approach.

[darrenburns]

Ward no longer uses name matching and instead relies on Python's import machinery to find fixtures, so this is no longer a problem.