enhancement: better diff for result mismatch

[xxchan]

We use space as separator for actual, but expected might use tab. This can look bad.

This can be tricky since we support custom validator.

https://github.com/risinglightdb/sqllogictest-rs/blob/27eb9f50993e10b36c1f4f68ad3afe499adbbb49/sqllogictest/src/runner.rs#L749-L759

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Here's an example from @BugenZhao https://github.com/risingwavelabs/risingwave/pull/9671#issuecomment-1542102712

[xxchan]

Maybe we can:

• change validator to sth like normalizer and output normalized results.
• Output normalized output if default_validator is used.

[wangrunji0408]

I'm curious what's the use case for validators? 👀

[xxchan]

Original added by @Xuanwo https://github.com/risinglightdb/sqllogictest-rs/pull/15

As indicated by its signature, the actual result is separated by columns Vec<Vec<String>>, but the expected result is not. So we need to normalize the results. validator is the most flexible form to achieve this, but not sure if it's really needed.

See also https://github.com/risinglightdb/sqllogictest-rs/issues/109

https://github.com/risinglightdb/sqllogictest-rs/blob/27eb9f50993e10b36c1f4f68ad3afe499adbbb49/sqllogictest/src/runner.rs#L411-L426

[skyzh]

I think we can parse both space and tab as separator in parser?

[skyzh]

Okay well this is not handled by parser. Then it might be a good idea to split by both space and tab in default validator :(