Improve statistics test coverage

[alamb]

Is your feature request related to a problem or challenge?

It is clear that the current statistics code is lacking tests . For example I was about to delete code #8172 but thankfully @berkaysynnada pointed out the code was actually different, yet not tests failed.

I spent some time auditing the codebase for tests, and here is what I found:

places that I think could do with some additional coverage

These places have tests, but we should review them to ensure that the coverage is adequte

Here are the places that do have tests, but the coverage probably needs to be reviewed

• LocalLimitExec: https://github.com/apache/arrow-datafusion/blob/fdf3f6c3304956cd56131d8783d7cb38a2242a9f/datafusion/physical-plan/src/limit.rs#L833
• UnionExec: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/union.rs#L696
• FilterExec: https://github.com/apache/arrow-datafusion/blob/e1c2f9583015db326b3439897376f14f6b83a99a/datafusion/physical-plan/src/filter.rs#L455

places that appear to be lacking coverage at all

Here are impl ExecutionPlan that implement statistics but I didn't find any tests (though I could have missed them)

• get_statistics_with_limit: https://github.com/apache/arrow-datafusion/blob/e54894c39202815b14d9e7eae58f64d3a269c165/datafusion/core/src/datasource/statistics.rs#L34-L33
• Join statistics: https://github.com/apache/arrow-datafusion/blob/e642cc2a94f38518d765d25c8113523aedc29198/datafusion/physical-plan/src/joins/utils.rs#L455-L454
• HashAggregateExec https://github.com/apache/arrow-datafusion/blob/67d66faa829ea2fe102384a7534f86e66a3027b7/datafusion/physical-plan/src/aggregates/mod.rs#L888-L887
• WindowExec: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/windows/window_agg_exec.rs#L250
• BoundedWindowExec: https://github.com/apache/arrow-datafusion/blob/c2e768052c43e4bab6705ee76befc19de383c2cb/datafusion/physical-plan/src/windows/bounded_window_agg_exec.rs#L311

Describe the solution you'd like

Review and add coverage as necessary to locations above

Describe alternatives you've considered

No response

Additional context

No response