Fix Windows FP discrepancy issue in test (#400)

* Fix Windows FP discrepancy issue in test

* Write changelog

CHANGELOG.md

@@ -13,7 +13,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * Remove unnecessary logging synchronisation #381 - @cyqsimon
 * Apply suggestions from new clippy lint clippy::assigning_clones #382 - @cyqsimon
 * Fix IPv6 socket detect logic #383 - @cyqsimon
-* Support build for `target_os`` `android` #384 - @flxo
+* Support build for `target_os` `android` #384 - @flxo
+* Fix Windows FP discrepancy issue in test #400 - @cyqsimon
 
 ## Added
 

src/display/components/display_bandwidth.rs

@@ -4,8 +4,10 @@ use derivative::Derivative;
 
 use crate::cli::UnitFamily;
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Derivative)]
+#[derivative(Debug)]
 pub struct DisplayBandwidth {
+    #[derivative(Debug(format_with = "fmt_f64"))]
     pub bandwidth: f64,
     pub unit_family: BandwidthUnitFamily,
 }
@@ -17,6 +19,14 @@ impl fmt::Display for DisplayBandwidth {
     }
 }
 
+/// Custom formatter with reduced precision.
+///
+/// Workaround for FP calculation discrepancy between Unix and Windows.
+/// See https://github.com/rust-lang/rust/issues/111405#issuecomment-2055964223.
+fn fmt_f64(val: &f64, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    write!(f, "{val:.10e}")
+}
+
 /// Type wrapper around [`UnitFamily`] to provide extra functionality.
 #[derive(Copy, Clone, Derivative, Default, Eq, PartialEq)]
 #[derivative(Debug = "transparent")]