Show a progress bar when running check_all

Replace the "Progress: xxx/yyy" with a progress bar when checking all
the exercises

src/app_state.rs

@@ -1,4 +1,9 @@
 use anyhow::{bail, Context, Result};
+use crossterm::{
+    queue,
+    style::{Print, ResetColor, SetForegroundColor},
+    terminal,
+};
 use std::{
     env,
     fs::{File, OpenOptions},
@@ -16,7 +21,7 @@ use crate::{
     embedded::EMBEDDED_FILES,
     exercise::{Exercise, RunnableExercise},
     info_file::ExerciseInfo,
-    term,
+    term::{self, progress_bar_with_success},
 };
 
 const STATE_FILE_NAME: &str = ".rustlings-state.txt";
@@ -428,10 +433,16 @@ impl AppState {
                             // No more exercises
                             break;
                         };
-                        if tx
-                            .send((exercise_ind, exercise.run_exercise(None, &this.cmd_runner)))
-                            .is_err()
-                        {
+
+                        // Notify the progress bar that this exercise is pending
+                        if tx.send((exercise_ind, None)).is_err() {
+                            break;
+                        };
+
+                        let result = exercise.run_exercise(None, &this.cmd_runner);
+
+                        // Notify the progress bar that this exercise is done
+                        if tx.send((exercise_ind, Some(result))).is_err() {
                             break;
                         }
                     }
@@ -443,28 +454,68 @@ impl AppState {
             // there are `tx` clones, i.e. threads)
             drop(tx);
 
+            // Print the legend
+            queue!(
+                stdout,
+                Print("Color legend:  "),
+                SetForegroundColor(term::PROGRESS_FAILED_COLOR),
+                Print("Failure"),
+                ResetColor,
+                Print("  -  "),
+                SetForegroundColor(term::PROGRESS_SUCCESS_COLOR),
+                Print("Success"),
+                ResetColor,
+                Print("  -  "),
+                SetForegroundColor(term::PROGRESS_PENDING_COLOR),
+                Print("Checking"),
+                ResetColor,
+                Print("\n"),
+            )
+            .unwrap();
+            // We expect at least a few "pending" notifications shortly, so don't
+            // bother printing the initial state of the progress bar and flushing
+            // stdout
+
+            let line_width = terminal::size().unwrap().0;
             let mut results = vec![AllExercisesResult::Pending; n_exercises];
-            let mut checked_count = 0;
-            write!(stdout, "\rProgress: {checked_count}/{n_exercises}")?;
-            stdout.flush()?;
+            let mut pending = 0;
+            let mut success = 0;
+            let mut failed = 0;
+
             while let Ok((exercise_ind, result)) = rx.recv() {
-                results[exercise_ind] = result.map_or_else(
-                    |_| AllExercisesResult::Error,
-                    |success| {
-                        checked_count += 1;
-                        if success {
-                            AllExercisesResult::Success
-                        } else {
-                            AllExercisesResult::Failed
+                match result {
+                    None => {
+                        pending += 1;
+                    }
+                    Some(Err(_)) => {
+                        results[exercise_ind] = AllExercisesResult::Error;
+                    }
+                    Some(Ok(true)) => {
+                        results[exercise_ind] = AllExercisesResult::Success;
+                        pending -= 1;
+                        success += 1;
+                    }
+                    Some(Ok(false)) => {
+                        results[exercise_ind] = AllExercisesResult::Failed;
+                        pending -= 1;
+                        failed += 1;
+                    }
                 }
-                    },
-                );
 
-                write!(stdout, "\rProgress: {checked_count}/{n_exercises}")?;
+                write!(stdout, "\r").unwrap();
+                progress_bar_with_success(
+                    stdout,
+                    pending,
+                    failed,
+                    success,
+                    n_exercises as u16,
+                    line_width,
+                )
+                .unwrap();
                 stdout.flush()?;
             }
 
-            Ok::<_, io::Error>((checked_count, results))
+            Ok::<_, io::Error>((success, results))
         })?;
 
         // If we got an error while checking all exercises in parallel,

src/term.rs

@@ -9,6 +9,10 @@ use std::{
     io::{self, BufRead, StdoutLock, Write},
 };
 
+pub const PROGRESS_FAILED_COLOR: Color = Color::Red;
+pub const PROGRESS_SUCCESS_COLOR: Color = Color::Green;
+pub const PROGRESS_PENDING_COLOR: Color = Color::Blue;
+
 pub struct MaxLenWriter<'a, 'b> {
     pub stdout: &'a mut StdoutLock<'b>,
     len: usize,
@@ -85,15 +89,26 @@ impl<'a> CountedWrite<'a> for StdoutLock<'a> {
     }
 }
 
-/// Terminal progress bar to be used when not using Ratataui.
+/// Simple terminal progress bar
 pub fn progress_bar<'a>(
     writer: &mut impl CountedWrite<'a>,
     progress: u16,
     total: u16,
     line_width: u16,
+) -> io::Result<()> {
+    progress_bar_with_success(writer, 0, 0, progress, total, line_width)
+}
+/// Terminal progress bar with three states (pending + failed + success)
+pub fn progress_bar_with_success<'a>(
+    writer: &mut impl CountedWrite<'a>,
+    pending: u16,
+    failed: u16,
+    success: u16,
+    total: u16,
+    line_width: u16,
 ) -> io::Result<()> {
     debug_assert!(total < 1000);
-    debug_assert!(progress <= total);
+    debug_assert!((pending + failed + success) <= total);
 
     const PREFIX: &[u8] = b"Progress: [";
     const PREFIX_WIDTH: u16 = PREFIX.len() as u16;
@@ -104,25 +119,67 @@ pub fn progress_bar<'a>(
     if line_width < MIN_LINE_WIDTH {
         writer.write_ascii(b"Progress: ")?;
         // Integers are in ASCII.
-        return writer.write_ascii(format!("{progress}/{total}").as_bytes());
+        return writer.write_ascii(format!("{}/{total}", failed + success).as_bytes());
     }
 
     let stdout = writer.stdout();
     stdout.write_all(PREFIX)?;
 
     let width = line_width - WRAPPER_WIDTH;
-    let filled = (width * progress) / total;
+    let mut failed_end = (width * failed) / total;
+    let mut success_end = (width * (failed + success)) / total;
+    let mut pending_end = (width * (failed + success + pending)) / total;
 
-    stdout.queue(SetForegroundColor(Color::Green))?;
-    for _ in 0..filled {
+    // In case the range boundaries overlap, "pending" has priority over both
+    // "failed" and "success" (don't show the bar as "complete" when we are
+    // still checking some things).
+    // "Failed" has priority over "success" (don't show 100% success if we
+    // have some failures, at the risk of showing 100% failures even with
+    // a few successes).
+    //
+    // "Failed" already has priority over "success" because it's displayed
+    // first. But "pending" is last so we need to fix "success"/"failed".
+    if pending > 0 {
+        pending_end = pending_end.max(1);
+        if pending_end == success_end {
+            success_end -= 1;
+        }
+        if pending_end == failed_end {
+            failed_end -= 1;
+        }
+
+        // This will replace the last character of the "pending" range with
+        // the arrow char ('>'). This ensures that even if the progress bar
+        // is filled (everything either done or pending), we'll still see
+        // the '>' as long as we are not fully done.
+        pending_end -= 1;
+    }
+
+    if failed > 0 {
+        stdout.queue(SetForegroundColor(PROGRESS_FAILED_COLOR))?;
+        for _ in 0..failed_end {
+            stdout.write_all(b"#")?;
+        }
+    }
+
+    stdout.queue(SetForegroundColor(PROGRESS_SUCCESS_COLOR))?;
+    for _ in failed_end..success_end {
         stdout.write_all(b"#")?;
     }
 
-    if filled < width {
+    if pending > 0 {
+        stdout.queue(SetForegroundColor(PROGRESS_PENDING_COLOR))?;
+
+        for _ in success_end..pending_end {
+            stdout.write_all(b"#")?;
+        }
+    }
+
+    if pending_end < width {
         stdout.write_all(b">")?;
     }
 
-    let width_minus_filled = width - filled;
+    let width_minus_filled = width - pending_end;
     if width_minus_filled > 1 {
         let red_part_width = width_minus_filled - 1;
         stdout.queue(SetForegroundColor(Color::Red))?;
@@ -133,7 +190,7 @@ pub fn progress_bar<'a>(
 
     stdout.queue(SetForegroundColor(Color::Reset))?;
 
-    write!(stdout, "] {progress:>3}/{total}")
+    write!(stdout, "] {:>3}/{}", failed + success, total)
 }
 
 pub fn clear_terminal(stdout: &mut StdoutLock) -> io::Result<()> {