PyTestArch is an open source library that allows users to define architectural rules and test their code against them. It is generally inspired by ArchUnit.
PyTestArch is available via PyPI and can be installed e.g. via pip: pip install pytestarch. To also install the
optional dependency matplotlib, which is required to draw the created dependency graphs, install pytestarch[visualization]
Three steps are required to test an architectural rule:
- Create an evaluable representation of the source code you want to test
from pytestarch import get_evaluable_architecture
evaluable = get_evaluable_architecture("/home/dummy/project", "/home/dummy/project/src")
This will scan all python files under /home/dummy/project/src for imports and build an internal representation that can later be queried. The first parameter /home/dummy/project helps PyTestArch to differentiate between internal and external dependencies. This evaluable can be used for multiple architectural rule checks; if you are using pytest, you could use a fixture for this evaluable object.
- Define an architectural rule
from pytestarch import Rule
rule = (
Rule()
.modules_that()
.are_named("project.src.moduleB")
.should_not()
.be_imported_by_modules_that()
.are_sub_modules_of("project.src.moduleA")
)
This rule represents the architectural requirements that a module named "project.src.moduleB" should not be imported by any module that is a submodule of "project.src.moduleA", excluding "project.src.moduleA" itself.
- Evaluate your code against this rule
rule.assert_applies(evaluable)
That's it!