Intermittent test failure for intervals_match_pg_values_f64 testcase

[czotomo]

Setup

Versions

• Rust: 1.60
• Diesel: master branch
• Database: doesn't matter
• Operating System Ubuntu 20 @ WSL

Problem Description

Every now and then, while running tests, I will get a panic in this function

thread 'pg::expression::extensions::interval_dsl::tests::intervals_match_pg_values_f64' panicked at '[quickcheck] TEST FAILED. Arguments: (29757356.223255634)', /home/tomo/.cargo/registry/src/github.com-1ecc6299db9ec823/quickcheck-1.0.3/src/tester.rs:165:28`

What are you trying to accomplish?

Run tests - bin/test

Checklist

• I have already looked over the issue tracker and the disussion forum for similar possible closed issues.

• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)
• This issue can be reproduced without requiring a third party crate

I can get this test to pass by rerunning the test script (sometimes it takes few tries to get it to work).
I have zero idea what might be the case.
FWIW this also shows up on a Macbook Pro @ Ventura MacOS with same Rust + Diesel version combo.

[weiznich]

That's one of the "fuzzing" tests. For reference:

diesel/diesel/src/pg/expression/extensions/interval_dsl.rs

Line 317 in 6ebee81

fn intervals_match_pg_values_f64() {

These are hard to debug. It would be helpful to investigate which of test calls causes the problem. After that we should be able to reproduce this by using the printed value + the test code behind the macro. Can you try to get these informations

[czotomo]

I'll see what I can do!

[czotomo]

@weiznich apologies for the delay
It seems it's only test_years function that fails, examples of values from quickcheck's panic:
(21634.64816430318)
(11.708915433687343)
(-5.152681370545959)
(842030.0574014463)
(313684.5795225026)
(81.90706702184103)

[weiznich]

@czotomo Thanks for providing these values. I will try to have a look at that.

[clouds56]

let val = -705.0759657500337; // or std::mem::transmute(13872785166456217622u64)
test_years(val); // this would fail
let value = val.years(); // PgInterval { microseconds: 0, days: 0, months: -8460 }
let sql_str = format!("'{} years'::interval", val); // PgInterval { microseconds: 0, days: 0, months: -8461 }

And I've tried select '-705.0759657500337 years'::interval; on my postgres it shows

      interval      
--------------------
 -705 years -1 mons
(1 row)

According to docs for postgres 16, the fraction part should be rounded instead of trunced.

Fractional parts of units greater than months are rounded to be an integer number of months, e.g. '1.5 years' becomes '1 year 6 mons'.

I've tried patch it with round and the test seems passed.

diesel/diesel/src/pg/expression/extensions/interval_dsl.rs

Lines 239 to 241 in a5c82df

	fn years(self) -> PgInterval {
	((self * 12.0).trunc() as i32).months()
	}

    fn years(self) -> PgInterval {
        ((self * 12.0).round() as i32).months()
    }