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AltWalker is an open source Model-Based Testing framework that supports running tests written in python3 and .NET/C#. You design your tests as a directed graph and AltWalker generates test cases from your graph (using GraphWalker) and executes them.

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AltWalker is an open source, Model-Based Testing framework.

Read the documentation on

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AltWalker is an open source Model-Based Testing framework that supports running tests written in python3 and .NET/C#. You design your tests as a directed graph and AltWalker generates test cases from your graph (using GraphWalker) and executes them.

Model-Based Testing

Model-Based Testing is a testing technique which offers a way of generating test cases based on models that describe the behavior (functionality) of the system under test.

The goal when designing models is to represent the part of the system under test, usually by one model for each functionality of your system.

With the help of graph theory we can dynamically generate multiple test scripts. A test script is a path passing through the model from a starting point till a condition is met.

Why use Model-Based Testing:

  • the abstraction layer added by the model gives your tests a better structure
  • the model can be updated to reflect the requirements changes making the tests easy to maintain
  • dynamically generates multiple test scripts based on different conditions (like coverage or length)
  • allows for a large number of tests to be created which results in a larger part of the system under test to be covered.


AltWalker is a test execution tool, which aims to make it easy to write and run your model-based tests. AltWalker uses GraphWalker to generate a path through the models.

For the test structure it uses an Object-Oriented approach inspired by python's unittest module. Every model is mapped to a class with the same name and each vertex and edge from the model is mapped to a method inside the class.

AltWalker also borrows the concept of test fixture from unit tests, and implements the following fixtures: setUpRun, tearDownRun, setUpModel and tearDownModel.

Now it supports running tests written in .NET/C# and Python3.

AltWalker Components

AltWalker has the following components:

  • Model: a directed graph, supplied by the user as a json or graphml file. A graph is composed from a list of vertices and a list of edges.

  • Generator and Stop Condition: used to specify how to generate a path and to decide when a path is complete.

  • Test Code: the implementation of the model(s) as code. Each model is mapped to a class and each vertex and edge is mapped to a method.

  • Planner: uses the model(s) and a pair of generator and stop condition to provide a path (a sequence of steps) through the model(s).

    Currently AltWalker provides two planners:

    • Online Planner
    • Offline Planner
  • Reporter: reports the output of the tests, the reporter is called on each event (e.g. step_start, step_end, ...).

  • Executor: for each step in the plan it looks up and calls the named method from the test code. In addition to the step methods, it also calls fixture methods if present (e.g. setUpModel, tearDownModel ...).

    Currently AltWalker provides three executors:

    • Python Executor
    • .NET Executor

    And an Http Executor that allows you to hook up your own executor via HTTP. You can read more about the Http Executor on the How to: Write your own executor page.

  • Walker: the test runner. Coordinates the execution of a test asking the Planner for the next step, executing the step using the Executor and reporting the progress using the Reporter.

There are two ways to run your tests:

  • Online Mode (using the Online Planner): Generate one step and then execute the step, until the path is complete.

  • Offline Mode (using the Offline Planner): Run a path from a sequence of steps. Usually the path is generated using the offline command.



Install AltWalker

To install altwalker run the following command in your command line:

$ pip install altwalker

To check that you have installed the correct version of AltWalker, run the following command:

$ altwalker --version

Living on the edge

If you want to work with the latest code before it’s released, install or update the code from the develop branch:

$ pip install -U git+

For a more detailed tutorial read the Installation section from the documentation.


Make a sample project and run the tests.

$ altwalker init test-project -l python
$ cd test-project
$ altwalker online tests -m models/default.json "random(vertex_coverage(100))"
[2019-08-06 16:28:44.030077] ModelName.vertex_A Running
[2019-08-06 16:28:44.030940] ModelName.vertex_A Status: PASSED

[2019-08-06 16:28:44.048492] ModelName.edge_A Running
[2019-08-06 16:28:44.048729] ModelName.edge_A Status: PASSED

[2019-08-06 16:28:44.064495] ModelName.vertex_B Running
[2019-08-06 16:28:44.064746] ModelName.vertex_B Status: PASSED


  Model Coverage..................100%
  Number of Models...................1
  Completed Models...................1
  Failed Models......................0
  Incomplete Models..................0
  Not Executed Models................0

  Edge Coverage...................100%
  Number of Edges....................1
  Visited Edges......................1
  Unvisited Edges....................0

  Vertex Coverage.................100%
  Number of Vertices.................2
  Visited Vertices...................2
  Unvisited Vertices.................0

Status:  PASS

Setting Up a Development Environment

Clone the repository:

$ git clone
$ cd altwalker

Install python dependencies:

$ pip install -r requirements.txt && \
  pip install -r requirements-dev.txt

Running Tests

$ pytest tests -s -v

Running tests with tox inside Docker

$ docker run  -it --rm -v "$(pwd):/altwalker" -w "/altwalker" altwalker/tests:tox tox


After you install the python dependencies to setup AltWalker CLI locally from code run:

$ pip install --editable .

Then from any command line you can access:

$ altwalker --help


After you install the python dependencies to generate the documentation run:

$ cd docs && \
  make clean && \
  make html

To see the documentation run:

$ open build/html/index.html

To rebuild the documentation on changes, with live-reload in the browser run:

$ sphinx-autobuild docs/source docs/build/html

Navigate to the documentation at

Further Reading/Useful Links:


Join our Gitter chat room or our Google Group to chat with us or with other members of the community.


This project is licensed under the GNU General Public License v3.0.

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