Development & Testing

Before submitting a change, you need to verify that it does not inadvertently break any existing functionality in Isso.

A test suite for the Python server part ensures that the most basic things are not broken, but it can only catch as many errors as it is configured to be aware of (this is called “test coverage”). For more information, see Testing the Server.

The Javascript client code is covered by both unit tests and end-to-end integration tests. The test coverage is very small at the moment - see this GitHub issue. For detailed instructions about running client tests, see Testing the Client.


Improvements to Isso’s test coverage and/or different testing strategies are always welcome! Please see the Contribute page for further information.

Sections covered in this document:

Development server

After you’ve set up Isso according to Install from Source, you will have a development server available at localhost:8080.

$ virtualenv .venv
$ source .venv/bin/activate
(.venv) $ isso -c contrib/isso-dev.cfg run

From there, the page localhost:8080/demo will be available, from where you can try out the embedded Isso widget yourself. For convenience, the development version of the bundled client code is used ( with source map).

This enables easier debugging - e.g. Firefox shows a webpack entry in the “Debugger” tab and shows the actual line of source code in any console traces.

Using docker

Testing via docker is not a requirement, but can make a few tests faster to set up, makes automation easier and ensures a consistent testing environment across developer machines.

Isso ships with several Dockerfiles - the ones under the docker/ folder are for creating a container that can run the unit and integration tests.

Build images

First, ensure all images are built:

# Prepare testbed image
$ make docker-testbed

This will take some time as headless chromium needs to be downloaded, once (~400Mb), as well as necessary libraries installed. Will be cached on subsequent runs.

# Create production image
$ make docker

Start server

Start up server part via docker compose:

$ docker compose up -d

Now you should have the Isso server part available at localhost:8080.

Running tests

Run unit tests:

$ make docker-js-unit

Run integration tests:

$ make docker-js-integration

(The --network part ensures that the client container can see the server part. This is not set automatically by docker since this container is considered a transient one)

Finally, bring down the containers again

$ docker compose down -v

(The -v flag removes the transient volumes again, ensuring each test run can start afresh).

Testing strategies

Manual testing

Here are a few ideas of how to manually test the client to reveal potentially uncovered scenarios:

  • Post a comment

  • Post an answer to a comment

  • Edit your comment

  • Test the admin interface

  • Delete a comment from admin, then try to delete from frontend

  • Reply to a comment that you have deleted from the admin/as another user

  • Use curl commands

  • Clear your cookies

  • Restore certain cookies

  • Embed into a single-page application (SPA)

  • Zoom inside your browser

  • Play with the embed parameters (data-isso-*)

  • Play with the server config

  • Test whether the docker container still works

Performance testing

Find a way to have 100, 1,000, 10,000, 100k commments at once.

Then, test responsiveness, speed of insertion, the updating of all timestamps every minute, and whatever else might be performance-related.

Here is an example to insert large amounts of data into an existing database at comments.db (might be better optimized):

echo "INSERT INTO threads (id, uri, title) VALUES ('1', '/demo/', 'Isso Test');" >> dummy.sql
for f in {1..500}; do
    echo "INSERT INTO comments (tid, created, remote_addr, text, mode, voters) VALUES (1, 100, '', 'hello', 1, 0);" >> dummy.sql
cat dummy.sql | sqlite3 comments.db

Also set the comments to be loaded at once to infinity:

<script data-isso-max-comments-top="inf" src="../js/"></script>

Unconventional testing

Be a chaos monkey! Think of unconventional ways of breaking Isso.

A QA engineer walks into a bar. Orders a beer. Orders 0 beers. Orders 99999999999 beers. Orders a lizard. Orders -1 beers. Orders a ueicbksjdhd.

First real customer walks in and asks where the bathroom is. The bar bursts into flames, killing everyone.



This section of the Isso documentation is incomplete. Please help by expanding it.

Click the Edit on GitHub button in the top right corner and read the GitHub Issue named Improve & Expand Documentation for further information.

What’s missing?

  • Explain the difference between unit and integration tests, maybe using cool analogies

  • Collect a few guides about testing philosophies and strategies

… and other things about testing in general that should be documented.