[no-Jira] Document mock.lastCall

[canac]

Description

I learned from @caleballdrin that mocks have a lastCall property. That feels cleaner than calls[0], so I'm adding it to the testing documentation.

Also fixed a couple of errors in the tests in the docs.

Checklist:

• I have given my PR a title with the format "MPDX-(JIRA#) (summary sentence max 80 chars)"
• I have applied the appropriate labels. (Add the label "On Staging" to get the branch automatically merged into staging.)
• I have requested a review from another person on the project

[aws-amplify-us-east-1]

This pull request is automatically being deployed by Amplify Hosting (learn more).

Access this pull request here: https://pr-854.d3dytjb8adxkk5.amplifyapp.com

[dr-bizz]

Thank you for updating this! I wonder if we should keep one Mock with [0][0] to show devs how it normally works.

[canac]

I wonder if we should keep one Mock with [0][0] to show devs how it normally works.

I was thinking that we could document our best practices for new code and not muddy the water with alternative ways of doing the same thing. There's plenty of code that uses .calls[0] but until/unless we change that them to .lastCall devs can hopefully either figure out what that means or Google it if they don't. Does that sound OK?

[dr-bizz]

I wonder if we should keep one Mock with [0][0] to show devs how it normally works.

I was thinking that we could document our best practices for new code and not muddy the water with alternative ways of doing the same thing. There's plenty of code that uses .calls[0] but until/unless we change that them to .lastCall devs can hopefully either figure out what that means or Google it if they don't. Does that sound OK?

In some tests the last call isn't the call you want to test. I know in most cases it is. I'm fine just using lastCall in the readMe as we want devs to know our best practices.