Project Standards

Development Environment

If you haven’t already, please visit “(b) Development Environment” to set up your local development environment.

Version Control

The repository uses a fork-based Git workflow with tag releases.

Guidelines

1. master must always be deployable

2. All changes are made through support branches on forks

3. Rebase with master to avoid/resolve conflicts

4. Make sure pre-commit checks pass when committing (enforced in CI/CD build)

5. Open a pull-request (PR) early for discussion

6. Once the CI/CD build passes and PR is approved, squash and rebase your commits

7. Merge PR into master and delete the branch

Things to Avoid

1. Don’t merge in broken or commented out code

2. Don’t commit onto master directly

3. Don’t merge with conflicts (handle conflicts upon rebasing)

Source: https://gist.github.com/jbenet/ee6c9ac48068889b0912

Pre-commit

The repository uses the pre-commit package to manage pre-commit hooks. These hooks help enforce quality assurance standards and identify simple issues at the commit level before submitting code reviews.

pre-commit Flow

Helpful Commands

Install into your cloned repo

conda activate e3sm_diags_env_dev
pre-commit install

Automatically run all pre-commit hooks (just commit)

# Tip: If there is an issue with pre-commit, you can bypass with the `--no-verify` flag. Please do NOT use this on a regular basis.
git commit -m '...'

pre-commit Output

Manually run all pre-commit hooks

pre-commit run --all-files

Run individual hook

# Available hook ids: trailing-whitespace, end-of-file-fixer, check-yaml, black, isort, flake8, mypy
pre-commit run <hook_id>

Squash and Rebase Commits

Before you merge a support branch back into master, the branch is typically squashed down to a single* buildable commit, and then rebased on top of the main repo’s master branch.

* In some cases, it might be logical to have multiple squashed commits, as long as each commit passes the CI/CD build

Why squash and rebase commits?

• Ensures build passes from the commit

• Cleans up Git history for easy navigation

• Makes collaboration and review process more efficient

• Makes handling conflicts from rebasing simple since you only have to deal with conflicted commits

• Makes git bisect easier and more effective to use. For example, it will show the exact commit that introduced a bug since the commit contains a relatively small changeset. On the otherhand, merge commits make it much harder since it includes a large changeset.

How to squash and rebase commits

Assuming that you followed “(b) Development Environment”:

1. Sync master with the main repo’s master

   git checkout master
   git rebase <upstream-origin>/master
   git push -f <fork-origin> master
   

2. Get the SHA of the commit OR number of commits to rebase to

   git log --graph --decorate --pretty=oneline --abbrev-commit
   

3. Squash commits:

   git rebase -i [SHA]
   
   # OR
   
   git rebase -i HEAD~[NUMBER OF COMMITS]
   

4. Rebase branch onto master

   git checkout <branch-name>
   git rebase master
   git push -f <fork-origin> <branch-name>
   

5. Make sure your squashed commit messages are refined

6. Force push to remote branch

   git push -f <fork-origin> <branch-name>
   

Source: https://blog.carbonfive.com/always-squash-and-rebase-your-git-commits/

Code Quality Assurance

This project uses several tools for code formatting, linting, and type checking listed below.

• Code Formatting: black

• Linting: flake8, isort

• Optional Type Checking: mypy

You can run them as hooks manually/automatically when committing using pre-commit, or manually through the terminal or IDE/text editor.

Helpful Commands

Run a tool

# Available tool names: black, flake8, isort, mypy
<tool_name> .

Continuous Integration / Continuous Delivery (CI/CD)

This project uses GitHub Actions to run two CI/CD workflows.

1. CI/CD Build Workflow

This workflow is triggered by Git pull_request and push (merging PRs) events to the the main repo’s master.

Jobs:

1. Run pre-commit for formatting, linting, and type checking

2. Run test suite in a conda environment

3. Publish latest master docs (only on push)

2. CI/CD Release Workflow

This workflow is triggered by the Git publish event, which occurs when a new release is tagged.

Jobs:

1. Publish new release docs

Style Guide

This project follows the Black code style. Please read about it more here.

API Documentation

In most cases, code should be self-documenting.

If necessary, documentation should explain why something is done, its purpose, and its goal. The code shows how it is done, so commenting on this can be redundant.

Guidelines

• Embrace documentation as an integral part of the overall development process

• Treat documenting as code and follow principles such as Don’t Repeat Yourself and Easier to Change

• Use comments and docstrings to explain ambigiuity, complexity, or to avoid confusion

• Co-locate API documentation with related code

• Use Python type annotations and type comments where helpful

Things to Avoid

• Don’t write comments as a crutch for poor code

• Don’t comment every function, data structure, type declaration