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Pull Request Requirements

Pull Request Requirements

Code Style, Hints, and Testing

Refer to our Coding Guidelines for the Coding Conventions and Rust Guidelines (opens in a new tab) | Rust Guidelines 中文版 (opens in a new tab) programming languages for detailed guidance about how to contribute to the project.

Writing clean code is just one of the many factors to care about when creating a pull request.

Large pull requests cause a significant overhead during the code review and facilitate bugs introduction in the codebase.

That's why you need to care about the pull request itself. It should be short, have a good title and description, and do just one thing.

Why should I care?

  • A good pull request will be reviewed quickly;
  • It reduces bug introduction into codebase;
  • It facilitates new developers onboarding;
  • It does not block other developers;
  • It speeds up the code review process and, consequently the product development.

The good pull requests look like:

  1. Pull request size

It should be small. The pull request must have a maximum of 250 lines of change.

  1. Feature breaking

Whenever possible, break pull-requests into smaller ones.

  1. Single Responsibility Principle

The pull request should do only one thing. Pull requests that follow the SRP reduces the overhead caused by revising a code that attempts to solve several problems. Before submitting a PR for review, try applying the principle of single responsibility. If this code is doing more than one thing, break it into other Pull Requests.

  1. Title

Make a self-explanatory title describing what the pull request does and self-explanatory.

  1. Description

Detail with what was changed, why it was changed, and how it was changed

It is recommended that you add the following to.git/hooks/pre-commit

#!/bin/sh
#
# An hook script to verify what is about to be committed.
# Inclued Code Style, Hints, and Testing
 
BASE=$(git rev-parse --show-toplevel)
 
$BASE/scripts/pr.sh -a

Operation Suggestions

  1. If you have added code that should be tested, add unit tests.

  2. If you have changed APIs, update the documentation. Make sure the documentation builds.

  3. Ensure all tests and lints pass on each and every commit that is part of your pull request using ./scripts/rust_lint.sh

  4. Submit your pull request, and describe in detail what is included in the Pull Request, and choose reviewers.

Authoring Clean Commits

Logically Separate Commits

Commits should be atomic (opens in a new tab) and broken down into logically separate changes. Diffs should also be made easy for reviewers to read and review so formatting fixes or code moves should not be included in commits with actual code changes.

Meaningful Commit Messages

Commit messages are important and incredibly helpful for others when they dig through the commit history in order to understand why a particular change was made and what problem it was intending to solve. For this reason commit messages should be well written and conform with the following format:

All commit messages should begin with a single short (50 character max) line summarizing the change and should skip the full stop. This is the title of the commit. It is also preferred that this summary be prefixed with "[area]" where the area is an identifier for the general area of the code being modified, e.g.

* [framework] enforce whitelist of nightly features
* [sequencer] removing VerificationPass trait

Following the commit title (unless it alone is self-explanatory), there should be a single blank line followed by the commit body which includes more detailed, explanatory text as separate paragraph(s). It is recommended that the commit body be wrapped at 72 characters so that Git has plenty of room to indent the text while still keeping everything under 80 characters overall.

The commit body should provide a meaningful commit message, which:

  • Explains the problem the change tries to solve, i.e. what is wrong with the current code without the change.
  • Justifies the way the change solves the problem, i.e. why the result with the change is better.
  • Alternative solutions considered but discarded, if any.

References in Commit Messages

If you want to reference a previous commit in the history of the project, use the format "abbreviated sha1 (subject, date)", with the subject enclosed in parentheses, like this:

Commit 895b53510 ("[consensus] remove slice_patterns feature", 2019-07-18) noticed that ...

This invocation of git show can be used to obtain this format:

git show -s --date=short --pretty='format:%h ("%s", %ad)' <commit>

If a commit references an issue please add a reference to the body of your commit message, e.g. issue #1234 or fixes #456. Using keywords like fixes, resolves, or closes will cause the corresponding issue to be closed when the pull request is merged.

Avoid adding any @ mentions to commit messages, instead add them to the PR cover letter.

Responding to Reviewer Feedback

During the review process a reviewer may ask you to make changes to your pull request. If a particular commit needs to be changed, that commit should be amended directly. Changes in response to a review should not be made in separate commits on top of your PR unless it logically makes sense to have separate, distinct commits for those changes. This helps keep the commit history clean.

If your pull request is out-of-date and needs to be updated because main has advanced, you should rebase your branch on top of the latest main by doing the following:

git fetch upstream
git checkout topic
git rebase -i upstream/main

You should not update your branch by merging the latest main into your branch. Merge commits included in PRs tend to make it more difficult for the reviewer to understand the change being made, especially if the merge wasn't clean and needed conflicts to be resolved. As such, PRs with merge commits will be rejected.

Bisect-able History

It is important that the project history is bisect-able so that when regressions are identified we can easily use git bisect to be able to pin-point the exact commit which introduced the regression. This requires that every commit is able to be built and passes all lints and tests. So if your pull request includes multiple commits be sure that each and every commit is able to be built and passes all checks performed by CI.

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