Extend support for batch operation mocking / assertions

[acline443]

Details

I may be misusing the library, so correct me if I am wrong. But I would like to write unit tests for functions that queue batches and then send the batch at the end. I would like to assert on the Updates/Insertions that are executed.

It seems to me like this is not currently supported as the SendBatch method does basically nothing:

func (c *pgxmock) SendBatch(context.Context, *pgx.Batch) pgx.BatchResults {
	return nil
}

Best assertion I can do is assert that the queued batch length is greater than 0.

Checklist

• pgxmock.go

• Add a new type ExpectedBatch with fields for the expected SQL statements and their arguments, and methods to set the expected results or errors.
  • Modify the SendBatch method to return mock batch results based on the queued expectations.
  • Add a new method ExpectBatch to the pgxmock type to queue an expected batch operation. This method should return an ExpectedBatch instance.
  • Update the ExpectationsWereMet method to also check if all expected batch operations were met.

• pgxmock_test.go

• Add unit tests for the new ExpectBatch method and the modified SendBatch method. These tests should cover various scenarios, including successful batch operations, batch operations that result in errors, and batch operations that do not meet the expectations.

[pashagolub]

Yes, unfortunately, SendBatch() is not currently supported. I do have plans for it. However, this will require some spare weeks to implement. One needs to implement pgx.BatchResults from scratch and incorporate this into the expectations paradigm. Of course, pull requests are more than welcome!

[pashagolub]

Wow! Thanks for working on this. I had a quick look over and it looks nice. Did you consider to use reflect.DeepEqual() instead of writing your own comparators? My main concern is introduction of unsafe in source code. Usually it means something was overengineered.

I'll try to spend some more time on this after pgconf.eu.

Thanks for your time and efforts!

[makubit]

The issue is that pgx.Batch type supports only two functions - Len() and Queue() and has inside unexported slice of already queued queries. I didn't know how to better reflect this Value, as DeepEqual() didn't work in this case. I will think about your suggestion, maybe something will come up to my mind.

Thanks for looking at this code ;)

[pashagolub]

Yeap, that's unfortunate. I thought reflect.DeepEqual is able to compare structs:

...
Struct values are deeply equal if their corresponding fields, both exported and unexported, are deeply equal.

[makubit]

The struggle with that is - that you have to batch the exact queries, I wanted a similar solution, that is used for Query, so in batch, we can reuse queryMatcher and also argsMatcher functionality. It, of course, doesn't need to be done this way, but DeepEqual has some limitations.
I'll think about your suggestion :)

[pashagolub]

I see now. That's not a simple question indeed :)