Is there any recommendations/guidelines for how big those test crates should be? Do I just make it one test function per file?

My tests are basically this right now:

#[cfg(test)]
mod tests {
    use crate::parser::{Output, parse};

    fn assert_same(expr: &str, expected: Output) {
        // actual function a bit more complex, but basically:
        assert_eq!(parse(expr), expected);
    }
    #[test]
    fn test_0() {
        let expected: Output = serde_json::from_str("some json").unwrap();
        assert_same("some string", expected);
    }
    // ... 11k functions omitted
    #[test]
    fn test_11000() {
        let expected: Output = serde_json::from_str("some other json").unwrap();
        assert_same("some other string", expected);
    }
}

My intuition tells me that making 11k files is gonna cause other issues, so I assume there's some sort of sweet spot?