Using Arcade to calculate a field based on the value of another field

[AlcoGISUser]

I'm creating a smart form for Field Maps and one of the requirements is to toggle one of the entries to either "Yes" or "No" using a switch. I have the default value set to "No". If the person in the field toggles the switch to "Yes" I want an Arcade expression to update the value for that same record in a date field with the current date of when the switch was toggled to "Yes" for that record.

I tried this but got an error:

var inspection_date = $feature.DATE_INSPECTED; /// date field to be changed with Arcade expression

var inspected = $feature.INSPECTED; /// toggle switch field

IIf(inspected = "Yes", inspection_date = Today(), null); /// condition

The error I get is:

Test execution error: Execution error - undefined. Verify test data.

I think I may need to use a for loop to achieve this but not sure how a response in a smart form would trigger the expression. Is this even possible? 

[KenBuja · Accepted solution]

When writing any logical function (either IF or IFF), you have to use "==" when evaluating a condition

var inspection_date = $feature.DATE_INSPECTED; /// date field to be changed with Arcade expression
var inspected = $feature.INSPECTED; /// toggle switch field
IIf(inspected == "Yes", inspection_date = Today(), null); /// condition

[AlcoGISUser]

Duh, I overlooked that. Weirdly enough the field populates in map viewer but not in field maps.