13.59The test I most want you to describe in an interview

Suppose flow:

POST customer
 ↓
validate
 ↓
Salesforce Upsert

Tell them:

“I'd have an MUnit test where Salesforce Upsert is mocked to return success and assert the response mapping. Then I'd have negative tests where Salesforce throws connectivity versus invalid-input errors to prove transient and permanent failures take different handlers. I'd also verify that invalid inbound requests never invoke Salesforce. Separately, I'd keep a smaller Salesforce sandbox suite proving the actual SOQL, permissions, external-ID upsert and validation-rule behavior.”

That answer demonstrates both:

MUnit knowledge
+
real-world testing judgment