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Thank you for showing interest in contributing to Esmerald. There are many ways you can help and contribute to the project.

Reporting possible bugs and issues

It is natural that you might find something that Esmerald should support or even experience some sorte of unexpected behaviour that needs addressing.

The way we love doing things is very simple, contributions should start out with a discussion. The potential bugs shall be raised as "Potential Issue" in the discussions, the feature requests may be raised as "Ideas".

We can then decide if the discussion needs to be escalated into an "Issue" or not.

When reporting something you should always try to:

  • Be as more descriptive as possible
  • Provide as much evidence as you can, something like:
    • OS platform
    • Python version
    • Installed dependencies
    • Code snippets
    • Tracebacks

Avoid putting examples extremely complex to understand and read. Simplify the examples as much as possible to make it clear to understand and get the required help.


To develop for Esmerald, create a fork of the Esmerald repository on GitHub.

After, clone your fork with the follow command replacing YOUR-USERNAME with your GitHub username:

$ git clone

Esmerald also uses hatch for its development, testing and release cycles.

Please make sure you run:

$ pip install hatch

Install the project dependencies

Not necessary because the dependencies are automatically installed by hatch. But if environments should be pre-initialized it can be done with hatch env

$ cd esmerald
$ hatch env create
$ hatch env create test
$ hatch env create docs


This is the recommended way but if you still feel you want your own virtual environment and all the packages installed there, you can always run scripts/install.

Enable pre-commit

The project comes with a pre-commit hook configuration. To enable it, just run inside the clone:

$ pre-commit install

Run the tests

To run the tests, use:

$ hatch run test:test

Because Esmerald uses pytest, any additional arguments will be passed. More info within the pytest documentation

For example, to run a single test_script:

$ hatch run test:test tests/

To run the linting, use:

$ hatch run lint


Improving the documentation is quite easy and it is placed inside the esmerald/docs folder.

To build all the documentation:

$ hatch run docs:build

Docs live (serving the docs)

During local development, there is a script that builds the site and checks for any changes, live-reloading:

$ hatch run docs:serve

It will serve the documentation on http://localhost:8000.

If you wish to serve on a different port:

$ hatch run docs:serve -p <PORT-NUMBER>

That way, you can edit the documentation/source files and see the changes live.


Alternatively, you can perform the same steps that scripts does manually.

Go into the language directory, for the main docs in English it's at docs/en/:

$ cd docs/en/

Then run mkdocs in that directory:

$ mkdocs serve --dev-addr 8000

Docs Structure

The documentation uses MkDocs.

And there are extra tools/scripts in place to handle translations in ./scripts/


You don't need to see the code in ./scripts/, you just use it in the command line.

All the documentation is in Markdown format in the directory ./docs/en/.

Many of the tutorials have blocks of code.

In most of the cases, these blocks of code are actual complete applications that can be run as is.

In fact, those blocks of code are not written inside the Markdown, they are Python files in the ./docs_src/ directory.

And those Python files are included/injected in the documentation when generating the site.


Help with translations is VERY MUCH appreciated! And it can't be done without the help from the community.

Here are the steps to help with translations.

Tips and guidelines

  • Check the currently existing pull requests for your language. You can filter the pull requests by the ones with the label for your language. For example, for Spanish, the label is lang-es.

  • Review those pull requests, requesting changes or approving them. For the languages I don't speak, I'll wait for several others to review the translation before merging.


You can add comments with change suggestions to existing pull requests.

Check the docs about adding a pull request review to approve it or request changes.

  • Check if there's a GitHub Discussion to coordinate translations for your language. You can subscribe to it, and when there's a new pull request to review, an automatic comment will be added to the discussion.

  • If you translate pages, add a single pull request per page translated. That will make it much easier for others to review it.

  • To check the 2-letter code for the language you want to translate, you can use the table List of ISO 639-1 codes.

Existing language

Let's say you want to translate a page for a language that already has translations for some pages, like Spanish.

In the case of Spanish, the 2-letter code is es. So, the directory for Spanish translations is located at docs/es/.


The main ("official") language is English, located at docs/en/.

Now run the live server for the docs in Spanish:

// Use the command "live" and pass the language code as a CLI argument
$ hatch run docs:serve_lang es


Alternatively, you can perform the same steps that scripts does manually.

Go into the language directory, for the Spanish translations it's at docs/es/:

$ cd docs/es/

Then run mkdocs in that directory:

$ mkdocs serve --dev-addr 8000

Now you can go to and see your changes live.

You will see that every language has all the pages. But some pages are not translated and have an info box at the top, about the missing translation.

Now let's say that you want to add a translation for the section Router.

  • Copy the file at:
  • Paste it in exactly the same location but for the language you want to translate, e.g.:


Notice that the only change in the path and file name is the language code, from en to es.

If you go to your browser you will see that now the docs show your new section (the info box at the top is gone). 🎉

Now you can translate it all and see how it looks as you save the file.

New Language

Let's say that you want to add translations for a language that is not yet translated, not even some pages.

Let's say you want to add translations for Creole, and it's not yet there in the docs.

Checking the link from above, the code for "Creole" is ht.

The next step is to run the script to generate a new translation directory:

// Use the command new-lang, pass the language code as a CLI argument
$ hatch run docs:new_lang ht

Successfully initialized: docs/ht

Now you can check in your code editor the newly created directory docs/ht/.

That command created a file docs/ht/mkdocs.yml with a simple config that inherits everything from the en version:

INHERIT: ../en/mkdocs.yml
site_dir: '../../site_lang/ht'


You could also simply create that file with those contents manually.

That command also created a dummy file docs/ht/ for the main page, you can start by translating that one.

You can continue with the previous instructions for an "Existing Language" for that process.

You can make the first pull request with those two files, docs/ht/mkdocs.yml and docs/ht/ 🎉

Preview the result

As already mentioned above, you can use the ./scripts/ with the live command to preview the results (or mkdocs serve).

Once you are done, you can also test it all as it would look online, including all the other languages.

To do that, first build all the docs:

// Use the command "build-all", this will take a bit
$ hatch run docs:build

You can also collect documentation for one language

// Use the command "build-lang", this will take a bit
$ hatch run docs:build_lang your_lang

This builds all those independent MkDocs sites for each language, combines them, and generates the final output at ./site_lang/.

Then you can serve that with the command serve:

// Use the command "dev" after running "build-all" or "build-lang -l your_lang"
$ hatch run docs:dev

Warning: this is a very simple server. For development, use mkdocs serve instead.
This is here only to preview a site with translations already built.
Make sure you run the build-all command first.
Serving at:

Building Esmerald

To build a package locally, run:

$ hatch build

Alternatively running:

$ hatch shell

It will install the requirements and create a local build in your virtual environment.


This section is for the maintainers of Esmerald.

Building the Esmerald for release

Before releasing a new package into production some considerations need to be taken into account.

  • Changelog

    • Like many projects, we follow the format from keepchangelog.
    • Compare main with the release tag and list of the entries that are of interest to the users of the framework.
      • What must go in the changelog? added, changed, removed or deprecated features and the bug fixes.
      • What is should not go in the changelog? Documentation changes, tests or anything not specified in the point above.
      • Make sure the order of the entries are sorted by importance.
      • Keep it simple.
  • Version bump

    • The version should be in of the main package.


Once the release PR is merged, create a new release that includes:


There will be a release of the version 0.2.3, this is what it should include.

  • Release title: Version 0.2.3.
  • Tag: 0.2.3.
  • The description should be copied from the changelog.

Once the release is created, it should automatically upload the new version to PyPI. If something does not work with PyPI the release can be done by running scripts/release.