Code Quality

sea 5

Slides

Introduction

There is no such thing as "perfect" code — there is only better code!

Instead of seeking perfection, we should seek for is "continuous improvement"...

We rarely write tests for our tests — a human must ensure that tests are valid.

Code Quality Is Everyone’s Responsibility including:
- Developer
- Tester
Code quality aspects

Aspect	Comments
Reliability	Probability that a system will run without failure over a specific period of operation
Maintainability	How easily software can be maintained
Testability	how well the software supports testing efforts
Portability	how usable the same software is in different environments
Reusability	whether existing assets — such as code — can be used again

Code quality Metrics

Metric	Comments
Defect Metrics	Number of defects — and severity of those defects — are important metrics of overall quality.
Complexity Metrics	Cyclomatic complexity for example
Testability	how well the software supports testing efforts
Portability	how usable the same software is in different environments

Ways to Improve Code Quality

Way	Comments
Use a coding standard	Makes everyone to use the right style
Analyze code — before code reviews	Analyze code as soon as it’s written
Follow code review best practices	Manual code reviews are still important for verifying the intent of the code
Refactor legacy code (when necessary)	help you clean up your codebase and lower its complexity

Write Maintainable Testable Good Code

readable
understandable
testable

Good Code
Does what it should
Follows a consistent style
It is easy to understand
Has been well-documented
It can be tested

Key Points
Avoid Code with global, mutable state - that any code can access, and any code can modify
A class should ask for its dependencies through its constructor rather than acquiring them itself - dependency injection
Optimize the code for the reader of the code, not the writer - Good Code Is Easily Read and Understood, in Part and in Whole
DRY - Don't repeat yourself - it is easier to maintain the code if it only exists in one place
Do the simplest, smallest thing you can do to add some value

Static Code Analysis

Run Static Code Analysis tools like PMD that attempt to highlight possible violations and vulnerabilities within ‘static’ (non-running) source code by using techniques such as Taint Analysis and Data Flow Analysis
Integrated with IDEs like VSCode, VSCode Apex PMD

New PMD report

Demo (will be part of PMD 6.50.0)

Screenshot

ESLint

ESLint VS Code Extension

ESLinting

Lightning Lint Service

Salesforce Lightning Code Scanner

Inclusive Language

Code Review

Peer Code Review
- Individual programmers are less than 50% efficient at finding bugs in their own software.
Code Walk-thru

Goals
The overall code health of code base is improving over time
The codebase stays consistent, maintainable

What to look for in a Code Review?
- The developers should test code well-enough that they work correctly by the time they get to code review.

Item	Comments
Design	Interactions in the code makes sense?
Functionality	Code is the manifest of what the developer intended?
Complexity	Is the code is more complex than it should be?. “can’t be understood quickly by code readers.” Over-engineering, where developers have made the code more generic than it needs to be
Tests	Unit, integration, or end-to-end tests
Naming	Developer pick good names for everything?
Comments	Developer has written clear comments in understandable Language. Comment should explain why some code exists, and should not be explaining what some code is doing. Regular expressions and complex algorithms often benefit greatly from comments that explain what they’re doing, for example. Note that comments are different from documentation of classes, modules, or functions, which should instead express the purpose of a piece of code, how it should be used, and how it behaves when used
Style	Developer follows the published style for a given programming language
Documentation	READMEs and generated reference docs

Code Review Summary

Item
The code is well-designed.
The functionality is good for the users of the code.
Any UI changes are sensible and look good.
Any parallel programming is done safely.
The code isn’t more complex than it needs to be.
The developer isn’t implementing things they might need in the future but don’t know they need now.
Code has appropriate unit tests.
Tests are well-designed.
The developer used clear names for everything.
Comments are clear and useful, and mostly explain why instead of what.
Code is appropriately documented
The code conforms to our style guides

Note to the developers

Item	Comments
Don’t Take it Personally	The goal of review is to maintain the quality of the codebase and the products
Fix the Code	1. Clarify the code 2.code comment that explains why the code is there (if required) 3. Modify the code
Think Collaboratively	If you disagree with the reviewer, find ways to collaborate: ask for clarifications, discuss pros/cons, and provide explanations of why your method of doing things is better for the codebase

Apex Best Practices

Practice
1. Bulkify your Code
2. Avoid SOQL Queries or DML statements inside FOR Loops
3. Bulkify your Helper Methods
4. Using Collections, Streamlining Queries, and Efficient For Loops
5. Streamlining Multiple Triggers on the Same Object
6. Querying Large Data Sets
7. Use of the Limits Apex Methods to Avoid Hitting Governor Limits
8. Use @future Appropriately
9. Writing Test Methods to Verify Large Datasets
10. Avoid Hardcoding IDs

Refer: APEX BEST PRACTICES

Naming Conventions

Based on Java Naming Conventions

Item	Notes	Example
Class Name	Should be unique, begin with an Uppercase letter. Do not contain underscores or spaces (except from the prefix and suffix). Should be nouns in mixed cases, with first letter of each interval word capitalized	AccountController
Variable Name	should be in mixed case (camelCase) with a lowercase first letter. Internal words start with capital letters	geocodingUrl
Method Name	Should be verbs, in mixed case with the first letter lowercase, with the first letter of each internal word capitalized - camelCase	getPagedPropertyList(...)
Constants	Class constants should be all UPPERCASE with words separated by underscores	private static final String BASE_URL = 'https://nominatim.openstreetmap.org/search?format=json'
Trigger	Trigger, should follow Salesforce Trigger – One trigger per object

Test Driven Development

Test Driven Development(TDD) = Test First Development(TFD) + refactoring
First write the test code before the functional code.
it's a way to get SelfTestingCode

TDD

Steps	Comments
Write a quick test	Basically just enough code to fail
Run the test	It should fail
Write functional code	So that pass the test
Finally, run the test	To check whether it has passed
Re-factor until tests PASS to continue with further development

LWC Best Practices

SOQL Best Practices

Best Practices

Lightning Performance Best Practices

Best Practices

Large Data Volumes

Best Practices

LWC Test Coverage - Jest

Write Jest tests to:
Test a component in isolation
Test a component’s public API (@api properties and methods, events)
Test basic user interaction (clicks)
Verify the DOM output of a component
Verify that events fire when expected

Simple Jest Demo

// app.js
function sum(a, b) {
  return a + b;
}
module.exports = sum;

// app.test.js
const sum = require('./app');

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

yarn test

yarn test
yarn run v1.22.17
$ jest
 PASS  ./app.test.js
  ✓ adds 1 + 2 to equal 3 (1 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.519 s, estimated 1 s
Ran all test suites.
✨  Done in 1.76s.

LWC Example (unedited)

Using Sa11y for 508 compliance

More info

LWC Recipes

Visualizing Code Coverage

This demo shows how to visualize code coverage in VS Code How to setup video - Enabling Apex Code Coverage Overlay in VS Code | Developer Quick Takes

LWC i18n

Demo showing how to use Custom Labels for localization

English (US)
French
Spanish
Refer: How to list custom labels using DX
Example:

sfdx mohanc:mdapi:ls -u mohan.chinnappan.n.sel@gmail.com -i listCL.json -t CustomLabel 
[ 'Greeting' ]
{
    "fullName": "Greeting",
    "language": "en_US",
    "protected": "true",
    "shortDescription": "Greeting",
    "value": "Hello World From LWC"
}

Resources

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sfdx mohanc:slides:gen -i cq.md -o cq.md.html -t 'Notes on Code Quality'

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Salesforce Development Notes