Apex DML Mocking

Welcome to the SFDX project home for blazing fast Apex unit tests! For your consideration, this is an example of how to implement the full CRUD (Create Read Update Delete) mocking implementation within your own Salesforce orgs. You can find out more information by perusing:

• force-app for implementation details
• example-app for an example Account Handler with mocking set up

Writing tests that scale as the size of your organization grows is an increasingly challenging problem in the Salesforce world. It's not uncommon in large companies for deploys to last several hours; the vast majority of that time is spent running tests to verify that your code coverage is good enough for the deploy to succeed. Tests don't need to take that long.

This repo shows you how you can mock your SOQL queries and DML statements in Apex by using lightweight wrappers that are dependency injected into your business logic objects. This allows you to replace expensive test setup and test teardown with a fake database. I've used this method to cut testing time down by 90%+ -- in a small org, with only a few hundred tests, running tests and deploying can be done in under five minutes (easily). In large orgs, with many hundreds or thousands of tests, overall testing time tends to scale more linearly with organizational complexity; there are additional optimizations that can be done in these orgs to keep deploys in the 10-15 minutes range.

DML Mocking Basics

Try checking out the source code for the DML wrapping classes:

• DML
• DMLMock

SOQL Mocking Basics

Take a look at the following classes to understand how you can replace raw SOQL in your code with testable (and extendable) strongly typed queries:

• Repository
• Query

Then, move on to the more complicated examples:

• AggregateRepository
• Aggregation
• AggregateRepositoryTests - a good example of how to use the above two classes
• FieldLevelHistoryRepo
• FieldLevelHistory

While opinionated in implementation, these classes are also just scratching the surface of what's possible when taking advantage of the Factory pattern in combination with the Repository pattern, including full support for:

• strongly typed subqueries (queries returning children records)
• strongly typed parent-level fields
• the ability to easily extend classes like Repository to include things like limits, order bys, etc ...

Dependency Injection Basics

The "Factory" pattern is of particular importance for DML mocking, because it allows you to have only one stub in your code for deciding whether or not to use mocks when running tests; crucially, the stub is only available when tests are being run: you cannot mock things in production-grade code.

You can have as many Factories as you'd like. I like to break my Factories out by responsibility:

• A factory for Trigger handlers
• A factory for basic classes
• The RepoFactory for CRUD related objects

It's a pretty standard approach. You might choose to break things down by (business) domain. There's no right way.

More Information

For more information on these patterns and how to use them, consider the free resources I've published under The Joys Of Apex. Thanks for your time!