doc/contribute/contributor_expectations.rst - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 .. _contributor-expectations:

 Contributor Expectations
 ########################

 Overview
 ********

 The Zephyr project encourages :ref:`contributors <contributor>` to submit
 changes as smaller pull requests. Smaller pull requests (PRs) have the following
 benefits:

 - Reviewed more quickly and reviewed more thoroughly. It's easier for reviewers
   to set aside a few minutes to review smaller changes several times than it is
   to allocate large blocks of time to review a large PR.

 - Less wasted work if reviewers or maintainers reject the direction of the
   change.

 - Easier to rebase and merge. Smaller PRs are less likely to conflict with other
   changes in the tree.

 - Easier to revert if the PR breaks functionality.

 .. note::
   This page does not apply to draft PRs which can have any size, any number of
   commits and any combination of smaller PRs for testing and preview purposes.
   Draft PRs have no review expectation and PRs created as drafts from the start
   do not notify anyone by default.


 Defining Smaller PRs
 ====================

 - Smaller PRs should encompass one self-contained logical change.

 - When adding a new large feature or API, the PR should address only one part of
   the feature. In this case create an :ref:`RFC proposal <rfcs>` to describe the
   additional parts of the feature for reviewers.

 - PRs should include tests or samples under the following conditions:

   - Adding new features or functionality.

   - Modifying a feature, especially for API behavior contract changes.

   - Fixing a hardware agnostic bug. The test should fail without the bug fixed
     and pass with the fix applied.

 - PRs must update any documentation affected by a functional code change.

 - If introducing a new API, the PR must include an example usage of the API.
   This provides context to the reviewer and prevents submitting PRs with unused
   APIs.


 Multiple Commits on a Single PR
 ===============================

 Contributors are further encouraged to break up PRs into multiple commits.  Keep
 in mind each commit in the PR must still build cleanly and pass all the CI
 tests.

 For example, when introducing an extension to an API, contributors can break up
 the PR into multiple commits targeting these specific changes:

 #. Introduce the new APIs, including shared devicetree bindings
 #. Update driver implementation X, with driver specific devicetree bindings
 #. Update driver implementation Y
 #. Add tests for the new API
 #. Add a sample using the API
 #. Update the documentation

 Large Changes
 =============

 Large changes to the Zephyr project must submit an :ref:`RFC proposal <rfcs>`
 describing the full scope of change and future work.  The RFC proposal provides
 the required context to reviewers, but allows for smaller, incremental, PRs to
 get reviewed and merged into the project. The RFC should also define the minimum
 viable implementation.

 Changes which require an RFC proposal include:

 - Submitting a new feature.
 - Submitting a new API.
 - :ref:`treewide-changes`.
 - Other large changes that can benefit from the RFC proposal process.

 Maintainers have the discretion to request that contributors create an RFC for
 PRs that are too large or complicated.

 PR Requirements
 ***************

 - Each commit in the PR must provide a commit message following the
   :ref:`commit-guidelines`.

 - All files in the PR must comply with :ref:`Licensing
   Requirements<licensing_requirements>`.

 - Follow the Zephyr :ref:`coding_style` and :ref:`coding_guidelines`.

 - PRs must pass all CI checks. This is a requirement to merge the PR.
   Contributors may mark a PR as draft and explicitly request reviewers to
   provide early feedback, even with failing CI checks.

 - When breaking a PR into multiple commits, each commit must build cleanly. The
   CI system does not enforce this policy, so it is the PR author's
   responsibility to verify.

 - When major new functionality is added, tests for the new functionality shall
   be added to the automated test suite. All API functions should have test cases
   and there should be tests for the behavior contracts of the API. Maintainers
   and reviewers have the discretion to determine if the provided tests are
   sufficient. The examples below demonstrate best practices on how to test APIs
   effectively.

     - :zephyr_file:`Kernel timer tests <tests/kernel/timer/timer_behavior>`
       provide around 85% test coverage for the
       :zephyr_file:`kernel timer <kernel/timer.c>`, measured by lines of code.
     - Emulators for off-chip peripherals are an effective way to test driver
       APIs. The :zephyr_file:`fuel gauge tests <tests/drivers/fuel_gauge/sbs_gauge>`
       use the :zephyr_file:`smart battery emulator <drivers/sensor/sbs_gauge/emul_sbs_gauge.c>`,
       providing test coverage for the
       :zephyr_file:`fuel gauge API <include/zephyr/drivers/fuel_gauge.h>`
       and the :zephyr_file:`smart battery driver <drivers/fuel_gauge/sbs_gauge/sbs_gauge.c>`.
     - Code coverage reports for the Zephyr project are available on `Codecov`_.

 - Incompatible changes to APIs must also update the release notes for the
   next release detailing the change.  APIs marked as experimental are excluded
   from this requirement.

 - Changes to APIs must increment the API version number according to the API
   version rules.

 - PRs must also satisfy all :ref:`merge_criteria` before a member of the release
   engineering team merges the PR into the zephyr tree.

 Maintainers may request that contributors break up a PR into smaller PRs and may
 request that they create an :ref:`RFC proposal <rfcs>`.

 .. _`Codecov`: https://app.codecov.io/gh/zephyrproject-rtos/zephyr

 Workflow Suggestions That Help Reviewers
 ========================================

 - Unless they applied the reviewer's recommendation exactly, authors must not
   resolve and hide comments, they must let the initial reviewer do it. The
   Zephyr project does not require all comments to be resolved before merge.
   Leaving some completed discussions open can sometimes be useful to understand
   the greater picture.

 - Respond to comments using the "Start Review" and "Add Review" green buttons in
   the "Files changed" view. This allows responding to multiple comments and
   publishing the responses in bulk. This reduces the number of emails sent to
   reviewers.

 - As GitHub does not implement |git range-diff|_, try to minimize rebases in the
   middle of a review. If a rebase is required, push this as a separate update
   with no other changes since the last push of the PR. When pushing a rebase
   only, add a comment to the PR indicating which commit is the rebase.

 .. |git range-diff| replace:: ``git range-diff``
 .. _`git range-diff`: https://git-scm.com/docs/git-range-diff

 PR Review Escalation
 ====================

 The Zephyr community is a diverse group of individuals, with different levels of
 commitment and priorities. As such, reviewers and maintainers may not get to a
 PR right away.

 The `Zephyr Dev Meeting`_ performs a triage of PRs missing reviewer approval,
 following this process:

 #. Identify and update PRs missing an Assignee.
 #. Identify PRs without any comments or reviews, ping the PR Assignee to start a
    review or assign to a different maintainer.
 #. For PRs that have otherwise stalled, the Zephyr Dev Meeting pings the
    Assignee and any reviewers that have left comments on the PR.

 Contributors may escalate PRs outside of the Zephyr Dev Meeting triage process
 as follows:

 - After 1 week of inactivity, ping the Assignee or reviewers on the PR by adding
   a comment to the PR.

 - After 2 weeks of inactivity, post a message on the `#pr-help`_ channel on
   Discord linking to the PR.

 - After 2 weeks of inactivity, add the `dev-review`_ label to the PR. This
   explicitly adds the PR to the agenda for the next `Zephyr Dev Meeting`_
   independent of the triage process. Not all contributors have the required
   privileges to add labels to PRs, in this case the contributor should request
   help on Discord or send an email to the `Zephyr devel mailing list`_.

 Note that for new PRs, contributors should generally wait for at least one
 Zephyr Dev Meeting before escalating the PR themselves.

 .. _Zephyr devel mailing list: https://lists.zephyrproject.org/g/devel


 .. _pr_technical_escalation:

 PR Technical Escalation
 =======================

 In cases where a contributor objects to change requests from reviewers, Zephyr
 defines the following escalation process for resolving technical disagreements.

 - Resolve in the PR among assignee, maintainers and reviewer.

   - Assignee to act as moderator if applicable.

 - Optionally resolve in the next `Zephyr Dev Meeting`_ or `Architecture Working
   Group`_ meeting with more Maintainers and project stakeholders.

   - The involved parties and the Assignee to be present when
     the (escalated) issue is discussed.

 - TSC: Assignees can escalate to the TSC voting members and get a binding
   resolution in the TSC by adding the `tsc`_ label on the PR.

 - Assignee to ensure the resolution of the escalation is reflected in the PR
   review.

 .. _#pr-help: https://discord.com/channels/720317445772017664/997527108844798012

 .. _dev-review: https://github.com/zephyrproject-rtos/zephyr/labels/dev-review

 .. _Zephyr Dev Meeting: https://github.com/zephyrproject-rtos/zephyr/wiki/Zephyr-Committee-and-Working-Group-Meetings#zephyr-dev-meeting

 .. _Architecture Project: https://github.com/zephyrproject-rtos/zephyr/projects/18

 .. _Architecture Working Group: https://github.com/zephyrproject-rtos/zephyr/wiki/Architecture-Working-Group

 .. _tsc: https://github.com/zephyrproject-rtos/zephyr/labels/tsc

 Reviewer Expectations
 #####################

 - Be respectful when commenting on PRs. Refer to the Zephyr `Code of Conduct`_
   for more details.

 - The Zephyr Project recognizes that reviewers and maintainers have limited
   bandwidth. Prioritize review requests in the following order:

     #. PRs related to items in the `Zephyr Release Plan`_.
     #. PRs that the reviewer has requested blocking changes.
     #. PRs assigned to the reviewer as the area maintainer.
     #. All other PRs.

 - Try to provide feedback on the entire PR in one shot. This provides the
   contributor an opportunity to address all comments in the next PR update.

 - Partial reviews are permitted, but the reviewer must add a comment indicating
   what portion of the PR they reviewed. Examples of useful partial reviews
   include:

   - Domain specific reviews (e.g. Devicetree).
   - Code style changes that impact the readability of the PR.
   - Reviewing commits separately when the requested changes cascade into the
     later commits.

 - Avoid increasing scope of the PR by requesting new features, especially when
   there is a corresponding :ref:`RFC <rfcs>` associated with the PR. Instead,
   reviewers should add suggestions as a comment to the :ref:`RFC <rfcs>`. This
   also encourages more collaboration as it is easier for multiple contributors
   to work on a feature once the minimum implementation has merged.

 - When using the "Request Changes" option, mark trivial, non-functional,
   requests as "Non-blocking" in the comment. Reviewers should approve PRs once
   only non-blocking changes remain. The PR author has discretion as to whether
   they address all non-blocking comments. PR authors should acknowledge every
   review comment in some way, even if it's just with an emoticon.

 .. _Code of Conduct: https://github.com/zephyrproject-rtos/zephyr/blob/main/CODE_OF_CONDUCT.md

 .. _Zephyr Release Plan: https://github.com/orgs/zephyrproject-rtos/projects/13
	.. _contributor-expectations:

	Contributor Expectations
	########################

	Overview
	********

	The Zephyr project encourages :ref:`contributors <contributor>` to submit
	changes as smaller pull requests. Smaller pull requests (PRs) have the following
	benefits:

	- Reviewed more quickly and reviewed more thoroughly. It's easier for reviewers
	to set aside a few minutes to review smaller changes several times than it is
	to allocate large blocks of time to review a large PR.

	- Less wasted work if reviewers or maintainers reject the direction of the
	change.

	- Easier to rebase and merge. Smaller PRs are less likely to conflict with other
	changes in the tree.

	- Easier to revert if the PR breaks functionality.

	.. note::
	This page does not apply to draft PRs which can have any size, any number of
	commits and any combination of smaller PRs for testing and preview purposes.
	Draft PRs have no review expectation and PRs created as drafts from the start
	do not notify anyone by default.


	Defining Smaller PRs
	====================

	- Smaller PRs should encompass one self-contained logical change.

	- When adding a new large feature or API, the PR should address only one part of
	the feature. In this case create an :ref:`RFC proposal <rfcs>` to describe the
	additional parts of the feature for reviewers.

	- PRs should include tests or samples under the following conditions:

	- Adding new features or functionality.

	- Modifying a feature, especially for API behavior contract changes.

	- Fixing a hardware agnostic bug. The test should fail without the bug fixed
	and pass with the fix applied.

	- PRs must update any documentation affected by a functional code change.

	- If introducing a new API, the PR must include an example usage of the API.
	This provides context to the reviewer and prevents submitting PRs with unused
	APIs.


	Multiple Commits on a Single PR
	===============================

	Contributors are further encouraged to break up PRs into multiple commits. Keep
	in mind each commit in the PR must still build cleanly and pass all the CI
	tests.

	For example, when introducing an extension to an API, contributors can break up
	the PR into multiple commits targeting these specific changes:

	#. Introduce the new APIs, including shared devicetree bindings
	#. Update driver implementation X, with driver specific devicetree bindings
	#. Update driver implementation Y
	#. Add tests for the new API
	#. Add a sample using the API
	#. Update the documentation

	Large Changes
	=============

	Large changes to the Zephyr project must submit an :ref:`RFC proposal <rfcs>`
	describing the full scope of change and future work. The RFC proposal provides
	the required context to reviewers, but allows for smaller, incremental, PRs to
	get reviewed and merged into the project. The RFC should also define the minimum
	viable implementation.

	Changes which require an RFC proposal include:

	- Submitting a new feature.
	- Submitting a new API.
	- :ref:`treewide-changes`.
	- Other large changes that can benefit from the RFC proposal process.

	Maintainers have the discretion to request that contributors create an RFC for
	PRs that are too large or complicated.

	PR Requirements
	***************

	- Each commit in the PR must provide a commit message following the
	:ref:`commit-guidelines`.

	- All files in the PR must comply with :ref:`Licensing
	Requirements<licensing_requirements>`.

	- Follow the Zephyr :ref:`coding_style` and :ref:`coding_guidelines`.

	- PRs must pass all CI checks. This is a requirement to merge the PR.
	Contributors may mark a PR as draft and explicitly request reviewers to
	provide early feedback, even with failing CI checks.

	- When breaking a PR into multiple commits, each commit must build cleanly. The
	CI system does not enforce this policy, so it is the PR author's
	responsibility to verify.

	- When major new functionality is added, tests for the new functionality shall
	be added to the automated test suite. All API functions should have test cases
	and there should be tests for the behavior contracts of the API. Maintainers
	and reviewers have the discretion to determine if the provided tests are
	sufficient. The examples below demonstrate best practices on how to test APIs
	effectively.

	- :zephyr_file:`Kernel timer tests <tests/kernel/timer/timer_behavior>`
	provide around 85% test coverage for the
	:zephyr_file:`kernel timer <kernel/timer.c>`, measured by lines of code.
	- Emulators for off-chip peripherals are an effective way to test driver
	APIs. The :zephyr_file:`fuel gauge tests <tests/drivers/fuel_gauge/sbs_gauge>`
	use the :zephyr_file:`smart battery emulator <drivers/sensor/sbs_gauge/emul_sbs_gauge.c>`,
	providing test coverage for the
	:zephyr_file:`fuel gauge API <include/zephyr/drivers/fuel_gauge.h>`
	and the :zephyr_file:`smart battery driver <drivers/fuel_gauge/sbs_gauge/sbs_gauge.c>`.
	- Code coverage reports for the Zephyr project are available on `Codecov`_.

	- Incompatible changes to APIs must also update the release notes for the
	next release detailing the change. APIs marked as experimental are excluded
	from this requirement.

	- Changes to APIs must increment the API version number according to the API
	version rules.

	- PRs must also satisfy all :ref:`merge_criteria` before a member of the release
	engineering team merges the PR into the zephyr tree.

	Maintainers may request that contributors break up a PR into smaller PRs and may
	request that they create an :ref:`RFC proposal <rfcs>`.

	.. _`Codecov`: https://app.codecov.io/gh/zephyrproject-rtos/zephyr

	Workflow Suggestions That Help Reviewers
	========================================

	- Unless they applied the reviewer's recommendation exactly, authors must not
	resolve and hide comments, they must let the initial reviewer do it. The
	Zephyr project does not require all comments to be resolved before merge.
	Leaving some completed discussions open can sometimes be useful to understand
	the greater picture.

	- Respond to comments using the "Start Review" and "Add Review" green buttons in
	the "Files changed" view. This allows responding to multiple comments and
	publishing the responses in bulk. This reduces the number of emails sent to
	reviewers.

	- As GitHub does not implement \|git range-diff\|_, try to minimize rebases in the
	middle of a review. If a rebase is required, push this as a separate update
	with no other changes since the last push of the PR. When pushing a rebase
	only, add a comment to the PR indicating which commit is the rebase.

	.. \|git range-diff\| replace:: ``git range-diff``
	.. _`git range-diff`: https://git-scm.com/docs/git-range-diff

	PR Review Escalation
	====================

	The Zephyr community is a diverse group of individuals, with different levels of
	commitment and priorities. As such, reviewers and maintainers may not get to a
	PR right away.

	The `Zephyr Dev Meeting`_ performs a triage of PRs missing reviewer approval,
	following this process:

	#. Identify and update PRs missing an Assignee.
	#. Identify PRs without any comments or reviews, ping the PR Assignee to start a
	review or assign to a different maintainer.
	#. For PRs that have otherwise stalled, the Zephyr Dev Meeting pings the
	Assignee and any reviewers that have left comments on the PR.

	Contributors may escalate PRs outside of the Zephyr Dev Meeting triage process
	as follows:

	- After 1 week of inactivity, ping the Assignee or reviewers on the PR by adding
	a comment to the PR.

	- After 2 weeks of inactivity, post a message on the `#pr-help`_ channel on
	Discord linking to the PR.

	- After 2 weeks of inactivity, add the `dev-review`_ label to the PR. This
	explicitly adds the PR to the agenda for the next `Zephyr Dev Meeting`_
	independent of the triage process. Not all contributors have the required
	privileges to add labels to PRs, in this case the contributor should request
	help on Discord or send an email to the `Zephyr devel mailing list`_.

	Note that for new PRs, contributors should generally wait for at least one
	Zephyr Dev Meeting before escalating the PR themselves.

	.. _Zephyr devel mailing list: https://lists.zephyrproject.org/g/devel


	.. _pr_technical_escalation:

	PR Technical Escalation
	=======================

	In cases where a contributor objects to change requests from reviewers, Zephyr
	defines the following escalation process for resolving technical disagreements.

	- Resolve in the PR among assignee, maintainers and reviewer.

	- Assignee to act as moderator if applicable.

	- Optionally resolve in the next `Zephyr Dev Meeting`_ or `Architecture Working
	Group`_ meeting with more Maintainers and project stakeholders.

	- The involved parties and the Assignee to be present when
	the (escalated) issue is discussed.

	- TSC: Assignees can escalate to the TSC voting members and get a binding
	resolution in the TSC by adding the `tsc`_ label on the PR.

	- Assignee to ensure the resolution of the escalation is reflected in the PR
	review.

	.. _#pr-help: https://discord.com/channels/720317445772017664/997527108844798012

	.. _dev-review: https://github.com/zephyrproject-rtos/zephyr/labels/dev-review

	.. _Zephyr Dev Meeting: https://github.com/zephyrproject-rtos/zephyr/wiki/Zephyr-Committee-and-Working-Group-Meetings#zephyr-dev-meeting

	.. _Architecture Project: https://github.com/zephyrproject-rtos/zephyr/projects/18

	.. _Architecture Working Group: https://github.com/zephyrproject-rtos/zephyr/wiki/Architecture-Working-Group

	.. _tsc: https://github.com/zephyrproject-rtos/zephyr/labels/tsc

	Reviewer Expectations
	#####################

	- Be respectful when commenting on PRs. Refer to the Zephyr `Code of Conduct`_
	for more details.

	- The Zephyr Project recognizes that reviewers and maintainers have limited
	bandwidth. Prioritize review requests in the following order:

	#. PRs related to items in the `Zephyr Release Plan`_.
	#. PRs that the reviewer has requested blocking changes.
	#. PRs assigned to the reviewer as the area maintainer.
	#. All other PRs.

	- Try to provide feedback on the entire PR in one shot. This provides the
	contributor an opportunity to address all comments in the next PR update.

	- Partial reviews are permitted, but the reviewer must add a comment indicating
	what portion of the PR they reviewed. Examples of useful partial reviews
	include:

	- Domain specific reviews (e.g. Devicetree).
	- Code style changes that impact the readability of the PR.
	- Reviewing commits separately when the requested changes cascade into the
	later commits.

	- Avoid increasing scope of the PR by requesting new features, especially when
	there is a corresponding :ref:`RFC <rfcs>` associated with the PR. Instead,
	reviewers should add suggestions as a comment to the :ref:`RFC <rfcs>`. This
	also encourages more collaboration as it is easier for multiple contributors
	to work on a feature once the minimum implementation has merged.

	- When using the "Request Changes" option, mark trivial, non-functional,
	requests as "Non-blocking" in the comment. Reviewers should approve PRs once
	only non-blocking changes remain. The PR author has discretion as to whether
	they address all non-blocking comments. PR authors should acknowledge every
	review comment in some way, even if it's just with an emoticon.

	.. _Code of Conduct: https://github.com/zephyrproject-rtos/zephyr/blob/main/CODE_OF_CONDUCT.md

	.. _Zephyr Release Plan: https://github.com/orgs/zephyrproject-rtos/projects/13