Pocha - mocha for python

pocha was created after spending sometime working in nodejs and finding that mocha made testing very easy in nodejs and there wasn't a similar option for python. pocha isn't an exact clone but has the various features I felt made writing tests in python easier and cleaner.

Installation

Latest build on pypi

pip install pocha

From source

pip install -e http://github.com/rlgomes/pocha

Basic usage

Writing your first test case

Writing a test case is a simple as decorator an existing method with it decorator. Lets write our first test which verifies that the builtin abs function works as desired:

from pocha import it

@it('can verify that abs works for negative numbers')
def negative_numbers():
    assert abs(-1) == 1

The above is all you'd have to do to make a python method become a pocha test. With the above in a file called test.py you can then run your test by using the pocha cli like so:

> pocha test.py

  ✓ can verify that abs works for negative numbers

  1 passing (0ms)

That was your first test case and it couldn't have been simpler. The correct way to use pocha though is to split up your tests into test suites and use the @describe decorator like so:

from pocha import describe, it

@describe('abs tests')
def _():

    @it('can verify that abs works for negative numbers')
    def negative_numbers():
        assert abs(-1) == 1

Which produces the following output:

> pocha test.py

  abs tests
    ✓ can verify that abs works for negative numbers

  1 passing (0ms)

Using before and after hooks

There are decorators for running a method before/after all the tests have executed in a suite or also to run before/after each test in a suite. The @before and @after decorators are used to provide hooks to run before and after a whole suite and generally used for setting up or tearing down some fixture used by all the tests in suite.

As an example the following:

from pocha import after, before, describe, it

@before
def _():
    print('before hook')

@after
def _():
    print('after hook')

@describe('suite')
def _():

    @it('test1')
    def test1():
        print('from test1')

Which as expected would produce the following when executed:

> pocha foo.py

before hook
  suite
from test1
    ✓ test1
after hook

  1 passing (0ms)

Then there are the @before_each and @after_each decorators which create hooks that will run before/after each test in a suite.

Builtin reporters

You can currently choose from 3 different builtin reporters. Here are the currently available ones and their output for the previous example test:

spec reporter (default)

The default reporter which mimics the same output that mochajs does with a few tweaks that should make all white space around elements the same.

> pocha test.py --reporter spec

  abs tests
    ✓ can verify that abs works for negative numbers

  1 passing (0ms)

dot reporter

The dot reporter is a minimalist reporter that can be quite useful if you have a lot of test cases and want to minimize the amount of output from pocha.

> pocha test.py --reporter dot

  .

  1 passing (0ms)

xunit reporter

The xunit reporter is of course for any continuous integration system to consume in order to report test results at a higher level.

> pocha test.py --reporter xunit
<?xml version="1.0" ?>
<test suite errors="0" failures="0" name="Pocha Tests" skip="0" tests="1">
  <test case classname="abs tests" name="can verify that abs works for negative numbers" time="0.000"/>
</test suite>

Tagging and filtering tests

pocha has the ability to tag tests and then allow the end user to run only tests that satisfy a given filter expression. As an example lets first extend the previous abs test example to something a bit more elaborate:

from pocha import describe, it

@describe('abs tests')
def _():

    @it('can verify that abs works for negative numbers', tags=['negative'])
    def _():
        assert abs(-1) == 1

    @it('can verify that abs works for zero', tags=['zero'])
    def _():
        assert abs(0) == 0

    @it('can verify that abs works for positive numbers', tags=['positive'])
    def _():
        assert abs(1) == 1

As you can see tagging is straightforward and running a specific test with a tag is also very straightforward:

> pocha test.py --filter negative

  abs tests
    ✓ can verify that abs works for negative numbers

  1 passing (0ms)

Skipping tests

pocha has the ability to skip tests easily by setting the skip=True flag on the describe or it decorator and then that test suite or test case will simply not execute or appear in the output. The tagging itself would look like so:

from pocha import describe, it

@describe('abs tests')
def _():

    @it('can verify that abs works for negative numbers', tags=['negative'])
    def _():
        assert abs(-1) == 1

    @it('can verify that abs works for zero', tags=['zero'], skip=True)
    def _():
        assert abs(0) == 0

    @it('can verify that abs works for positive numbers', skip=True)
    def _():
        assert abs(1) == 1

The output of running the above test would look like so:

  abs tests
    ✓ can verify that abs works for negative numbers

  1 passing (0ms)

Debugging tests

When debugging tests sometimes you simply want to run a single test suite or test case and instead of tagging the test and then proceeding to specify the exact tag on the command line you want to simply mark that test unit as the "only" thing to execute. So there's an only keyword you can set to True and pocha will run just that test suite or test case. Here's what the usage looks like:

from pocha import describe, it

@describe('abs tests')
def _():

    @it('can verify that abs works for negative numbers', only=True)
    def _():
        assert abs(-1) == 1

    @it('can verify that abs works for zero')
    def _():
        assert abs(0) == 0

    @it('can verify that abs works for positive numbers')
    def _():
        assert abs(1) == 1

Executing the above even when specifying a filter expression on the command line will always result in the following output:

  abs tests
    ✓ can verify that abs works for negative numbers

  1 passing (0ms)

Development

You can easily run the existing unittests by installing the test dependencies:

pip install -r test-requirements.txt

Then using pocha to run the unittests like so:

pocha

Also be aware that python setup.py test works without having to install the test dependencies in your python virtualenv.

If you have any issues to report please feel free to open a new issue here. Also feel free to open PR's and submit patches to make pocha better for others.