External Test Plugin


The External Test Plugin supports testing of a cmd2 application by exposing access cmd2 commands with the same context as from within a cmd2 Python Scripts. This interface captures stdout, stderr, as well as any application-specific data returned by the command. This also allows for verification of an application’s support for Python Scripts and enables the cmd2 application to be tested as part of a larger system integration test.

Example cmd2 Application

The following short example shows how to mix in the external test plugin to create a fixture for testing your cmd2 application.

Define your cmd2 application

import cmd2
class ExampleApp(cmd2.Cmd):
    """An class to show how to use a plugin"""
    def __init__(self, *args, **kwargs):
        # gotta have this or neither the plugin or cmd2 will initialize
        super().__init__(*args, **kwargs)

    def do_something(self, arg):
        self.last_result = 5
        self.poutput('this is the something command')

Defining the test fixture

In your test, define a fixture for your cmd2 application

import cmd2_ext_test
import pytest

class ExampleAppTester(cmd2_ext_test.ExternalTestMixin, ExampleApp):
    def __init__(self, *args, **kwargs):
        # gotta have this or neither the plugin or cmd2 will initialize
        super().__init__(*args, **kwargs)

def example_app():
    app = ExampleAppTester()
    yield app

Writing Tests

Now write your tests that validate your application using the app_cmd() function to access the cmd2 application’s commands. This allows invocation of the application’s commands in the same format as a user would type. The results from calling a command matches what is returned from running an python script with cmd2’s run_pyscript command, which provides stdout, stderr, and the command’s result data.

from cmd2 import CommandResult

def test_something(example_app):
    # execute a command
    out = example_app.app_cmd("something")

    # validate the command output and result data
    assert isinstance(out, CommandResult)
    assert str(out.stdout).strip() == 'this is the something command'
    assert out.data == 5