Functional testing

Each function is compared to specifications to ascertain that it returns the required outputs.

Framework

For Functional testing, Pytest is preferred.

Setting up

Before installing pytest, ensure you have python installed. Manage your environment using conda, venv, pyenv, poetry or shell.nix(NixOS).

Installation

First, we start by creating an environment(conda specific.)

# New environment
conda create --name <env_name>

To install pytest, open your terminal:

pip install pytest

For an existing project with a requirements.txt or environment.yml file

# requirements.txt
conda create --name <env_name> --file requirements.txt

# or

# environment.yml
conda env create -f environment.yml

Usage

To use pytest you need to create a tests directory in your project. Inside the test directory, you can create tests.

In the test file, import the pytest module.

import pytest

Creating tests

The test files have a naming convention. The file name has to have prefix test_ or suffix _test.py. For example: test_*.py and *_test.py respectively.

NOTE: Using the prefix test_ is preferred.

The test functions also do have a naming convention. The function has to have a prefix test_. For example:

...

# test function
def test_addition():
    ...

To create new functional tests using pytest:

Function in Project/example.py module.

...

# function module
def addition(a, b):
    return a + b

Test function in tests/ directory.

import pytest
import Project.example

# test function
def test_addition():
    c = addition(3, 2)
    assert c == 5

...

Running tests

To run the tests, open your terminal and navigate to your test directory:

pytest

The above command will run all tests present in the tests/ directory.

To run a single test use:

pytest tests/test_example.py

For more, refer to invoking pytest.

Pytest fixtures

Fixtures are functions that provide resources or perform actions required for test execution. By encapsulating these setup and teardown steps into fixtures: - It streamlines the test code and promotes code re-usability - It improves the overall readability and maintainability of the test suite.

Fixture example that contains raster path that can be used by multiple tests:

import pytest

# fixtures
@pytest.fixture()
def vector_data():
    path = 'vector.geojson'
    return path

@pytest.fixture()
def raster_data():
    path = 'raster.tif'
    return path

def test_mask_raster(raster_data, vector_path):
    raster = mask_raster(raster_data, vector_path)
    ...

Pytest in Django projects

pytest-django is a pytest plugin used to test django applications.

Installation

To install pytest-django, open you terminal and activate your environment. Then type:

pip install pytest-django

Setting up and configuration

pytest-django is set up in the django_project directory. Navigate to the django_project, ensure there is a pytest.ini with the following configurations:

[pytest]
env =
    DJANGO_SETTINGS_MODULE=core.settings.test
    AZURE_B2C_CLIENT_ID=

In the django_project, there are django apps each in a different directory. You need to create a tests folder in each directory and add an __init.py__ file to make a package.

In the tests directory, create tests based on guidelines. An example of the directory structure:

$ project             # root directory
    django_project    # django project
      __init__.py
      core
  ->  <django_app_1>  # django application
        __init__.py
    ->  tests         # tests directory
          __init__.py
      ->  test_example.py   # test file <test_*.py>
      frontend
      manage.py
      pytest.ini

Running tests

To run pytest in django, navigate to the django_project directory the run:

pytest

All the tests in each django application will be executed.

To run a particular test use:

pytest <django_app>/tests/test_example.py

Pytest with BDD

BDD library for pytest.