Unit Testing

Unit testing should be used to test small units of code in an isolated and deterministic fashion. Unit tests should avoid performing communication with external APIs and should prefer to use mocking. Testing actual interaction with external APIs should be performed via Test Playbooks. Unit testing is currently supported for Python and PowerShell (no JS). This doc outlines Python setup. For PowerShell see here.

Environment Setup

In order to work with unit testing, the integration or automation script needs to be developed in package (directory) structure, where the yml file is separated from the python file and resides in its own directory.

Setup Pipenv

To run locally the unit tests we want to setup a virtual environment with all required dependencies (both runtime and development). To achieve this we use Pipenv.

Our recommended way to setup an integration into the package (directory) structure is to use: desmito-sdk split-yml. See full command documentation here.

Manual Setup:

  • Install pipenv: Follow the instructions.
  • Copy base Pipenv files: Copy the base Pipfile and Pipfile.lock files to the target package directory from: demisto_sdk/commands/lint/resources.
  • Install additional runtime dependencies: using: pipenv install <dependency>. For example: pipenv install ldap3
  • Sync Pipenv: (including dev dependencies) by running: pipenv sync --dev
  • Enable Virtual Env: To enable the Pipenv virtual env in the shell run: pipenv shell. To exit the virtual env simply run: exit.

You should now have a managed virtual environment to run unit tests locally.

Setup PyCharm

We recommend using PyCharm with the Cortex XSOAR Plugin. This is optional and you can also run/debug unit tests with other ides (such as VS Code), but only PyCharm currently has a dedicated plugin, which can manage the yml file via the UI and also provide remote execution. See: https://plugins.jetbrains.com/plugin/12093-demisto-add-on-for-pycharm. Setup:

Use main in Integration/Automation

When writing unit tests you will import the Integration/Automation file in order to test specific files. Thus, there is need to make sure that the file is written in such a way that when importing it will not execute. This can be done with a simple main function which is called depending on how the file was executed. When the Integration/Automation script is called by Cortex XSOAR it will have the property __name__ set to either __builtin__ or builtins depending upon the python version. Adding the following code will ensure the script is not run when imported by the unit tests:

# python2 uses __builtin__ python3 uses builtins
if __name__ == "__builtin__" or __name__ == "builtins":
main()

Write Your Unit Tests

Unit tests should be written in a separate Python file named: <your_choice>_test.py. Within the unit test file, each unit test function should be named: test_<your name>. More information on writing unit tests and their format is available at the PyTest Docs. Good place to see example unit tests: Proofpoint TAP v2 integration

Mocking

We use pytest-mock for mocking. pytest-mock is enabled by default and installed in the base environment mentioned above. To use a mocker object, simply pass it as a parameter to your test function. The mocker can then be used to mock both the demisto object and also external APIs. An example of using a mocker object is available here.

Running Your Unit Tests

Command Line

To run your unit tests from the command line simply run from within the virtual env:

pytest -v

Sample run:

It is also possible to run from outside the virtual env by running:

pipenv run pytest -v

Run with PyCharm

Open the unit test file within PyCharm. You will see a green arrow next to each unit test function. When pressing the arrow you will get a prompt to either Debug or Run the unit test. Set breakpoints as needed and Debug the test.

Sample clip of debugging in PyCharm:

Run With Docker

CircleCI build will run the unit tests within the docker image the Integration/Automation will run with. To test and run locally the same way CircleCI runs the tests, run the demisto-sdk lint command

Run the script with -h to see command line options:

demisto-sdk lint -h
Usage: demisto-sdk lint [OPTIONS]
Lint command will perform:
1. Package in host checks - flake8, bandit, mypy, vulture.
2. Package in docker image checks - pylint, pytest, powershell - test, powershell -
analyze.
Meant to be used with integrations/scripts that use the folder (package) structure. Will
lookup up what docker image to use and will setup the dev dependencies and file in the target
folder.
Options:
-h, --help Show this message and exit.
-i, --input PATH Specify directory of integration/script
-g, --git Will run only on changed packages
-a, --all-packs Run lint on all directories in content repo
-v, --verbose Verbosity level -v / -vv / .. / -vvv [default: 2]
-q, --quiet Quiet output, only output results in the end
-p, --parallel INTEGER RANGE Run tests in parallel [default: 1]
--no-flake8 Do NOT run flake8 linter
--no-bandit Do NOT run bandit linter
--no-mypy Do NOT run mypy static type checking
--no-vulture Do NOT run vulture linter
--no-pylint Do NOT run pylint linter
--no-test Do NOT test (skip pytest)
--no-pwsh-analyze Do NOT run powershell analyze
--no-pwsh-test Do NOT run powershell test
-kc, --keep-container Keep the test container
--test-xml PATH Path to store pytest xml results
--failure-report PATH Path to store failed packs report
-lp, --log-path PATH Path to store all levels of logs

Sample output:

Common Unit Testing Use Cases

Multi variables assertion

Most functions we write have several edge cases. When writing a unit test for this type of function all edge cases need to be tested. For example let's examine the following python function:

def convert_string_to_type(string: str) -> Union[str, bool, int]:
"""
Converts the input string to it's object type
:param string: The input string
:return: The converted object
"""
if string.isnumeric():
return int(string)
elif string in ['true', 'false', 'True', 'False']:
return bool(string)
return string

A naive unit test will be as follows:

def test_convert_string_to_type():
from File import convert_string_to_type
string = 'true'
assert convert_string_to_type(string) == True
string = '432'
assert convert_string_to_type(string) == 432
string = 'str'
assert convert_string_to_type(string) == 'str'

The correct way to test this function is using the @pytest.mark.parametrize fixture:

@pytest.mark.parametrize('string, output', [('true', True), ('432', 432), ('str', 'str')])
def test_convert_string_to_type(string, output):
assert convert_string_to_type(string) == output

We declare the inputs and outputs in the following format: 'input, output', [(case1_input, case1_output), (case2_input, case2_output), ...] (Note that more than two variables can be delivered)

After declaring the variables and assigning their values, you need to assign the variables to the test function. In the example above we assign the variables 'string' and 'output' to the test function.

To read more on parametrize fixtures, visit: https://docs.pytest.org/en/latest/parametrize.html

An example of a test using the paramertrize fixture is avialable here.

Testing Exceptions

If a function is raising an exception in some case we want to test the right exception is raised and that the error message is correct. For example, for testing the following function:

def function():
raise ValueError('this is an error msg')

We first need to import the raises function from pytest using this line of code:

from pytest import raises

Then, we test the exception being raised.

def test_function():
from File import function
with raises(ValueError, match='this is an error msg'):
function()

If the function raises a ValueError with proper error message, the test will pass.

Troubleshooting Tips

  • The demisto-sdk lint by default prints out minimal output. If for some reason it is failing and not clear, run the script with -v for verbose output.

  • When running mypy against python 2 code and the file contains non-ascii characters it may fail with an error of the sort:

    can't decode file 'ThreatConnect.py': 'ascii' codec can't decode byte 0xe2 in position 47329: ordinal not in range(128).

    To find the character use the following python one liner:

    python -c "index = 47329; f = open('Integrations/ThreatConnect/ThreatConnect.py'); d = f.read(); print(d[index-20:index+20])"

  • The script creates a container image which is used to run pytest and pylint. The container image will be named: devtest<origin-image>-[deps hash]. For example: devtestdemisto/python:1.3-alpine-1b9f5bee16a24c3f5463e324c1bb075. You can examine the image if needed by simple using docker run. For example:

docker run --rm -it devtestdemisto/python:1.3-alpine-1b9f5bee16a24c3f5463e324c1bb075e sh

If you have faced the error ValueError: unknown locale: UTF-8 when running demisto-sdk lint, add these lines to your ~/.bash_profile:

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8
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