From dc04d638f1dd1e7aa50efa088c1d100e2bad1fe6 Mon Sep 17 00:00:00 2001
From: Mateusz Kwapich <mitrandir@fb.com>
Date: Wed, 21 May 2025 14:06:17 +0100
Subject: [PATCH 1/4] [style] demonstrate the rounding problem in percentage
 rendering

---
 src/style.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/style.rs b/src/style.rs
index dc40ca1a..cead30ed 100644
--- a/src/style.rs
+++ b/src/style.rs
@@ -1055,4 +1055,21 @@ mod tests {
         assert_eq!(&buf[2], "bar");
         assert_eq!(&buf[3], "baz");
     }
+
+    #[test]
+    fn test_pct_precision() {
+        // seeing something that's not finished as 100% hurts my eyes
+        const WIDTH: u16 = 80;
+        let pos = Arc::new(AtomicPosition::new());
+        pos.set(358);
+        let state = ProgressState::new(Some(359), pos);
+
+        let style = ProgressStyle::default_bar()
+                .template(
+                    &format!("{{pos}}/{{len}} {{percent}}%"),
+                ).unwrap();
+        let mut buf = Vec::new();
+        style.format_state(&state, &mut buf, WIDTH);
+        assert_eq!(&buf[0], "358/359 100%");
+    }
 }

From 247e4d01adad0bc9f4e26231fed96c7cda9871bd Mon Sep 17 00:00:00 2001
From: Mateusz Kwapich <mitrandir@fb.com>
Date: Wed, 21 May 2025 14:21:14 +0100
Subject: [PATCH 2/4] [style] 358/359 is NOT 100%

By default rust float formatting doesn't round down - in fact they use
round_ties_even udner the hood: https://doc.rust-lang.org/std/primitive.f32.html#method.round_ties_even

For percentage calculations this is not great - in particular we shouldn't show 100% when the operation is not fully complete.
---
 src/style.rs | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/style.rs b/src/style.rs
index cead30ed..533b0cc7 100644
--- a/src/style.rs
+++ b/src/style.rs
@@ -302,7 +302,7 @@ impl ProgressStyle {
                                 buf.write_fmt(format_args!("{}", HumanCount(len))).unwrap();
                             }
                             "percent" => buf
-                                .write_fmt(format_args!("{:.*}", 0, state.fraction() * 100f32))
+                                .write_fmt(format_args!("{:.*}", 0, (state.fraction() * 100f32).floor()))
                                 .unwrap(),
                             "percent_precise" => buf
                                 .write_fmt(format_args!("{:.*}", 3, state.fraction() * 100f32))
@@ -1062,7 +1062,7 @@ mod tests {
         const WIDTH: u16 = 80;
         let pos = Arc::new(AtomicPosition::new());
         pos.set(358);
-        let state = ProgressState::new(Some(359), pos);
+        let state = ProgressState::new(Some(359), pos.clone());
 
         let style = ProgressStyle::default_bar()
                 .template(
@@ -1070,6 +1070,10 @@ mod tests {
                 ).unwrap();
         let mut buf = Vec::new();
         style.format_state(&state, &mut buf, WIDTH);
-        assert_eq!(&buf[0], "358/359 100%");
+        assert_eq!(&buf[0], "358/359 99%");
+        buf.clear();
+        pos.set(359);
+        style.format_state(&state, &mut buf, WIDTH);
+        assert_eq!(&buf[0], "359/359 100%");
     }
 }

From fdcaa673343b1f22b1c131cba2daa1077e693569 Mon Sep 17 00:00:00 2001
From: Mateusz Kwapich <mitrandir@fb.com>
Date: Wed, 21 May 2025 18:38:58 +0100
Subject: [PATCH 3/4] fix format

---
 src/style.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/style.rs b/src/style.rs
index 533b0cc7..907b1155 100644
--- a/src/style.rs
+++ b/src/style.rs
@@ -302,7 +302,11 @@ impl ProgressStyle {
                                 buf.write_fmt(format_args!("{}", HumanCount(len))).unwrap();
                             }
                             "percent" => buf
-                                .write_fmt(format_args!("{:.*}", 0, (state.fraction() * 100f32).floor()))
+                                .write_fmt(format_args!(
+                                    "{:.*}",
+                                    0,
+                                    (state.fraction() * 100f32).floor()
+                                ))
                                 .unwrap(),
                             "percent_precise" => buf
                                 .write_fmt(format_args!("{:.*}", 3, state.fraction() * 100f32))
@@ -1065,9 +1069,8 @@ mod tests {
         let state = ProgressState::new(Some(359), pos.clone());
 
         let style = ProgressStyle::default_bar()
-                .template(
-                    &format!("{{pos}}/{{len}} {{percent}}%"),
-                ).unwrap();
+            .template(&format!("{{pos}}/{{len}} {{percent}}%"))
+            .unwrap();
         let mut buf = Vec::new();
         style.format_state(&state, &mut buf, WIDTH);
         assert_eq!(&buf[0], "358/359 99%");

From ac58e514012d3cd978bab4e092569dcfd1b72f3d Mon Sep 17 00:00:00 2001
From: Mateusz Kwapich <mitrandir@fb.com>
Date: Wed, 21 May 2025 20:08:24 +0100
Subject: [PATCH 4/4] [style] show that percent_precise also shows 100% on
 incomplete operations

---
 src/style.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/style.rs b/src/style.rs
index 907b1155..44f59e11 100644
--- a/src/style.rs
+++ b/src/style.rs
@@ -1079,4 +1079,23 @@ mod tests {
         style.format_state(&state, &mut buf, WIDTH);
         assert_eq!(&buf[0], "359/359 100%");
     }
+
+    #[test]
+    fn test_pct_precise_precision() {
+        const WIDTH: u16 = 80;
+        let pos = Arc::new(AtomicPosition::new());
+        pos.set(999999);
+        let state = ProgressState::new(Some(1000000), pos.clone());
+
+        let style = ProgressStyle::default_bar()
+            .template(&format!("{{pos}}/{{len}} {{percent_precise}}%"))
+            .unwrap();
+        let mut buf = Vec::new();
+        style.format_state(&state, &mut buf, WIDTH);
+        assert_eq!(&buf[0], "999999/1000000 100.000%");
+        buf.clear();
+        pos.set(1000000);
+        style.format_state(&state, &mut buf, WIDTH);
+        assert_eq!(&buf[0], "1000000/1000000 100.000%");
+    }
 }