Peer reviewing checklist

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These are points to consider while peer-reviewing issues. Further explanation below.

[] Syntax
[] Whitespace
[] Output
[] Language
[] Databases
[] Testing (instructions and automated tests)
[] Security
[] Documentation
[] Git
[] Third party code
[] Sanity check

Acceptable check-marks are Y (for yes), N (for no) or - (for not applicable). All N check-marks should be accompanied by an explanation of the problem that still needs to be addressed.


To allow the community of Moodle developers to work together, conventions should be followed.

  • The code is easy to understand and, where it isn't, comments have been provided.
  • Variables are named correctly (all lower case, no camel-case, no underscores).
  • Functions are named correctly (all lower case, no camel-case, underscores allowed).
  • PHP DocBlocks have been updated and adhere to coding style guide.
  • Where functions are being removed, the Deprecation process is followed.
  • The code doesn't use deprecated functions.
  • $_GET, $_POST, $_REQUEST, $_COOKIE, and $_SESSION are never used.

See the Coding style guide for details.


Unnecessary whitespace changes can cause conflicts when committing code.

Ensure that:

  • there are no unnecessary blank lines in the new code;
  • blank lines do not contain spaces;
  • there are no unnecessary changes to whitespace in other areas on the file;


Output needs to be controlled by renderers to achieve consistency and correct application of themes.

Ensure that:

  • output renders are used to generate output strings, including HTML tags;
  • HTML output is valid XHTML;
  • no inline styles have been used in HTML output (everything has to be in CSS);
  • CSS has been added to the appropriate CSS files (base, specific area, sometimes canvas); and
  • the code doesn't use buffered output unless absolutely necessary.
  • all visual output has a RTL alternative included

feedback any notices (E_STRICT, etc) seen into the MDL.


To achieve appropriate internationalisation of Moodle, language strings must be managed correctly.

Ensure that:

  • new language strings are named correctly (all lower case, no camel-case, underscores are permissible in some cases);
  • help strings are named and formatted as described in Help strings;
  • language strings are used instead of hard-coded strings for text output;
  • language strings have not been removed or renamed, had their meaning changed or had their parameters changed in stable branches (permitted only in master); and
  • AMOS commands have been specified when moving or copying language strings.


DB calls are the greatest performance bottleneck in Moodle.

If there is SQL code you can test quickly then do so.

Ensure that:

  • there are minimal DB calls (no excessive use of the DB); and
  • the code uses SQL compatible with all the supported DB engines (check all selected fields appear in an 'order by' clause).

Testing instructions and automated tests

It is the developer's responsibility to test code before integration. Issues should not be sent for peer review without tests so that the peer reviewer can assess their quality and use them to consider the scope of the issue.

Ensure that:

  • there are specific testing instructions that state how, as well as what, to test. Please ensure that the testing instructions are in the correct format: Behat gherkin;
  • new unit tests have been added when there is a change in functionality; and
  • unit tests pass for related areas where changes have been made.
  • Behat tests pass for related areas where changes have been made, especially when it involved UI changes.


The user community relies on Moodle being responsibly secure.

Ensure that:

  • user login is checked where an identity is needed;
  • sesskey values are checked before all write actions where appropriate (some read actions as well);
  • capabilities are checked where roles differ; and
  • if the issue itself is a security issue, the security process is being followed.
    • Ensure that the fix is not available in a public repository (ie. a personal Github account); stand-alone patches should be provided instead.
    • The issue will not be integrated until just before the next minor version release.


Work does not stop when code is integrated.

Ensure that:

  • Appropriate labels have been added when there has been a function change, particularly
    • qa_test_required (significant functional change),
    • docs_required (any functional change, usually paired with ui_change),
    • dev_docs_required (any change to APIs, usually paired with api_chage),
    • ui_change (any functional change, usually paired with docs_required, except ui_change remains permanetly), and
    • api_change (any change to APIs that devs will need to know about, usually paired with dev_docs_required, except api_change remains permanetly).


Ensure that:

  • the commit matches the Coding style
  • the Git history is clean and the work has been rebased to logical commits; and
  • the original author of the work provided as a patch has been given credit within the commit (as author of in the commit message if changes were made).

Third party code

Does the change contain third party code? If so, ensure that:

  • The code is licensed under a GPL compatible license.
  • The instructions for upgrading/importing the library and contained within a readme_moodle.txt file.
  • The library is recorded in a thirdparty.xml file, including licensing information.
  • Third party code has been scanned to check for url accessible entry points that could be exploited. These should either be disabled, or if required functionality they should be checked for security weaknesses.
  • Does not duplicate the functionality of any existing api or third party library in core.

Sanity check

Ensure that:

  • the code seems to solve the described problem completely within its reported scope (and further issues have been created to resolve remaining parts or further refactoring);
  • the code makes sense in relation to the broader codebase (look at the whole function, not just the altered code); and
  • the developer has searched for and fixed other areas that may also have been affected by the same problem.
  • if any version numbers have been changed in version.php files, then the changes follow the rule for updating version numbers in core.

See Also