asserto 0.0.3a0

A fluent DSL for python assertions.

Asserto

Asserto is a clean, fluent and powerful assertion library for python. We recommend using pytest as a test runner (as asserto has been developed using it internally) however any test runner will work just fine. Using it in your framework (non-test) code is also fine as well!

The main features of asserto are (and will be):

• Chaining and assertion fluency using a builder-esque API.
• Hard assertions by default; but soft when used in a python context.
• Clean, rich diffs to highlight problems and improve debuggability.
• Dynamicism, access underlying attributes and methods on pretty much any object using attr_is(expected) syntax.
• A robust set of APIs including all builtin types; files; regex and much, much more.
• Extensibility; registering your own assertion functions is easy! consider sending us a patch for useful ones.
• Automatic warnings in some cases of human error for assertions; i.e creating an instance but never checking anything.
• Much much more.

from asserto import asserto

def test_foo() -> None:
    asserto("Hello").has_length(5).matches(r"\w{5}$").ends_with("lo").starts_with("Hel")

If you use pytest; a fixture is available for an Asserto factory function:

def test_bar(asserto) -> None:  # No imports; just use the fixture.
    asserto("Hello").has_length(5).matches(r"\w{4}$").ends_with("lo").starts_with("Hel")

If you want to check many assertions in a single test without failing until after all:

def test_baz(asserto) -> None:
    with asserto("Baz") as context:
        # asserto when used in a python context is run in 'soft' mode;
        # upon exiting the context; congregated errors are subsequently raised (if any)
        context.starts_with("B")
        context.ends_with("z")
        context.is_equal_to("Baz")
        context.is_length(2)  # Uh oh a failure!

Results in:

    def test_foo(asserto) -> None:
>       with asserto("Bar") as context:
E       AssertionError: 1 Soft Assertion Failures
E       [AssertionError("Length of: 'Bar' was not equal to: 2")]