## TL;DR

The accepted fix: wrap the non-setup DML in System.runAs with the current user, which separates the setup-object DML from the rest.

## Steps

1. When your Salesforce test creates both Users and business records, wrap the business-record setup in System.runAs using the running user. Setup objects and non-setup objects cant share a DML context, and runAs gives the test a clean boundary. This applies to any setup object, not just User.

## When to use

You are seeing this: When your Salesforce test creates both Users and business records, wrap the business-record setup in System.runAs using the running user. Use this skill when you run into "Salesforce tests: wrap setup DML in System.runAs to avoid MIXED_DML".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.