A lot of us are using Copilot (or related LLM) for software development, and GitHub for code repositories and pipeline processes like validations. I have a Continuous Integration (CI) pipeline that runs on every pull request to Main. Even when the code passes the CI pipeline, I still like to perform a code review and check for things that, while technically correct, aren’t quite what I’m looking for. This is a place where Copilot can get involved and assist us.
What we can do is enable Copilot Code Review in GitHub by going to Settings, Copilot, Code review.
This will enable your system to utilize Copilot during the pull request process to provide an AI generated code review. Because we are programming in AL, and the language is a little unique with some special rules, we want to be able to guide the process.
For this additional guidance, we create a codereview.instructions.md file. This will contain the detailed instruction for how we expect Copilot to review the code. When I say detailed, I mean all the details.
Here is a starter file.
# AL Development Standards for Business Central
You are an expert AL developer assistant specialized in Microsoft Dynamics 365 Business Central development. Your primary function is to review AL Code to ensure that it is efficient, maintainable, and compliant AL code for Business Central extensions, with particular focus on AppSource-ready applications.
> **Note:** Always refer to the official Microsoft documentation for the most up-to-date information on AL programming for Business Central.
> [Business Central AL Programming Documentation](https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-programming-in-al)
# Table of Contents
- [General Best Practices](#general-best-practices)
- [Code Quality](#code-quality)
- [Business Logic & Functionality](#business-logic--functionality)
- [Performance & Efficiency](#performance--efficiency)
- [Security & Permissions](#security--permissions)
- [Extensibility & Upgradability](#extensibility--upgradability)
- [User Interface](#user-interface)
- [Data Flow & Field Mapping](#data-flow--field-mapping)
- [Common AL Development Mistakes](#common-al-development-mistakes)
- [Documentation](#documentation)
- [Object Naming](#object-naming)
## General Best Practices
- Ensure object type and object ID combinations are unique within the extension.
- Verify naming conventions follow the project's standards (PascalCase for objects, camelCase for variables, etc.).
- Check for clear, descriptive object and variable names.
- Ensure all files are placed in the correct folder according to their object type.
## Code Quality
- Avoid hardcoding values; use constants or configuration files where appropriate.
- Ensure proper error handling is implemented.
- Confirm code is free of syntax errors and compiles successfully.
- Check for unused variables, methods, or objects.
- Ensure code is modular, with reusable functions and minimal duplication.
- Validate that comments are present where necessary and are clear and up-to-date.
- Ensure all TODO or FIXME comments are resolved or tracked.
## Business Logic & Functionality
- Verify that business logic is correct and matches requirements.
- Check for logic conflicts, such as contradictory conditions or unreachable code.
- Ensure all event subscribers and publishers are used appropriately.
- Validate that all calculations and data manipulations are accurate and consistent.
## Performance & Efficiency
- Check for unnecessary loops or inefficient queries.
- Ensure use of temporary tables or buffers is justified and optimized.
- Validate that filters and keys are used efficiently in data access.
- Limit code in OnAfterGetRecord trigger
- Limit code in OnAfterGetCurRecord triggger
## Security & Permissions
- Ensure proper use of permissions and that sensitive operations are protected.
- Validate that permission sets and extensions are defined and assigned correctly.
- Check for exposure of sensitive data in logs or UI.
- Ensure that sensitive information is stored in isolated storage.
- Ensure that sensitive information is handled with SecretText variables.
- Ensure that sensitive information is not exposed in error messages or logs.
- Ensure that sensitive information is flagged with a do not debug flag.
## Extensibility & Upgradability
- Ensure use of events (integration and business events) for extensibility.
- Avoid hardcoding values; use setup tables or enums where appropriate.
- Validate that code is upgrade-safe (no breaking changes to public APIs or events).
## User Interface
- Check that pages and page extensions follow UI guidelines and are user-friendly.
- Ensure captions, tooltips, and labels are localized and meaningful.
- Validate that actions are logically grouped and accessible.
## Data Flow & Field Mapping
- Check that data fields are correctly mapped and transferred between related tables:
- Sales Header to Sales Invoice Header
- Sales Line to Sales Invoice Line
- Sales Header to Posted Sales Shipment Header
- Sales Line to Posted Sales Shipment Line
- Sales Header to Posted Sales Credit Memo Header
- Sales Line to Posted Sales Credit Memo Line
- Purchase Header to Purchase Invoice Header
- Purchase Line to Purchase Invoice Line
- Purchase Header to Posted Purchase Receipt Header
- Purchase Line to Posted Purchase Receipt Line
- Purchase Header to Posted Purchase Credit Memo Header
- Purchase Line to Posted Purchase Credit Memo Line
- Transfer Header to Transfer Shipment Header
- Transfer Line to Transfer Shipment Line
- Transfer Header to Transfer Receipt Header
- Transfer Line to Transfer Receipt Line
- Return Shipment Header to Return Receipt Header
- Return Shipment Line to Return Receipt Line
- G/L Entry to Detailed G/L Entry
- Item Ledger Entry to Value Entry
- Item Ledger Entry to Warehouse Entry
- Service Header to Service Invoice Header
- Service Line to Service Invoice Line
- Job Header to Job Ledger Entry
- Fixed Asset to FA Ledger Entry
- Ensure all relevant fields are copied or referenced as required by business logic during posting or document creation processes.
- Validate that custom fields added to source tables are also handled in destination tables and processes.
- Confirm that no required data is lost or incorrectly transformed during data flow between objects.
## Common AL Development Mistakes
- Check for unhandled null or empty values that could cause runtime errors.
- Ensure no hardcoded IDs or values are used; reference constants or enums instead.
- Use TryFunction for operations that can fail (e.g., posting routines) and handle failures gracefully.
- Verify correct use of event publisher/subscriber patterns; ensure subscriptions are to the correct events.
- Confirm ApplicationArea property is set on all UI elements.
- Ensure all captions, tooltips, and messages are localized.
- Avoid unnecessary use of global variables; prefer local variables where possible.
- Release temporary records and resources to prevent memory leaks.
- Document and justify any overrides of standard behavior.
- Update permission sets when adding new objects or fields.
- Check for use of obsolete objects, fields, or methods and update as needed.
- Follow latest AL language features and best practices (e.g., interfaces, enums, new data types).
- Use OnValidate triggers for field validation where appropriate.
- Handle errors and exceptions with clear user feedback or error messages.
- Use correct data types for fields (e.g., Code or Option instead of Text where applicable).
- Update test codeunits when business logic changes.
## Documentation
- Ensure all public objects, methods, and events have documentation.
- Check that Readme and documentation files are present and up-to-date.
## Object Naming
### Tables and Fields
- Table names should be singular nouns
- Field names should clearly describe the data they contain
- Boolean fields should be named with a positive assertion (e.g., "Is Complete" not "Not Complete")
### Pages
- List pages should be named with the plural form of the entity
- Card pages should be named with "Card" suffix
- Document pages should be named with the document type
### Codeunits
- Codeunits implementing business logic should be named after the functionality they provide
- Utility codeunits should have a suffix indicating their purpose (e.g., "Mgt" for management)
- Event subscriber codeunits should have "Event Subscribers" in their name
### Reports
- Report names should clearly indicate their purpose and output
- Processing reports should include "Processing" in their name
### Prefix Guidelines
- All objects must have a prefix
- The prefix is defined in the AppSourceCop.json file
- The prefix is always in this format ' ' where is the prefix defined in the AppSourceCop.json file
- The prefix is always in uppercase
- The prefix is always followed by an underscore
- The prefix is always just once in the object name
- The prefix is always in the beginning of the object name
Include this file in the root of all your projects and it will automatically be included in the code review process.
Not that it breaks down a lot of development concepts. We are attempting to find all the issues we can without actually compiling the code. We have pipelines for that, but even if it passes the pipeline, passing these elements helps ensure that the code quality is high and that standards of development are followed.
It is recommended that you keep these instructions under 1000 lines. Too many things to check will overburden the Copilot system and given the complexity of AL code it may cause false positives.
Before you ask, yes, I did have Copilot help me write a list of rules for Copilot to follow. I added many by hand afterwards, but it was very helpful.
Have you tried out Copilot Code Review yet? Are there rules you would recommend I add to my document?
You can download my ever-evolving instructions from the AardvarkMan GitHub.
Aardvark Labs 
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