tests: Addressed additional CR comments and added tests for tail-logs

src/utils.rs

@@ -59,7 +59,7 @@ pub fn init_logging_config() -> log4rs::Config {
   let trigger = SizeTrigger::new(10 * 1024 * 1024);
   let roller = FixedWindowRoller::builder()
     .build(&archive_pattern, 3)
-    .unwrap();
+    .expect("Failed to build log roller");
   let policy = CompoundPolicy::new(Box::new(trigger), Box::new(roller));
 
   let logfile = RollingFileAppender::builder()
@@ -67,7 +67,7 @@ pub fn init_logging_config() -> log4rs::Config {
       "{d(%Y-%m-%d %H:%M:%S%.3f)(utc)} <{i}> [{l}] {f}:{L} - {m}{n}",
     )))
     .build(log_path, Box::new(policy))
-    .unwrap();
+    .expect("Failed to build rolling file appender");
 
   log4rs::Config::builder()
     .appender(Appender::builder().build("logfile", Box::new(logfile)))
@@ -104,16 +104,29 @@ pub async fn tail_logs(no_color: bool) -> Result<()> {
     .seek(SeekFrom::End(0))
     .with_context(|| "Unable to tail log file")?;
 
-  let mut lines = reader.lines();
-
-  tokio::spawn(async move {
+  tokio::task::spawn_blocking(move || {
+    let mut line_buf = String::new();
     loop {
-      if let Some(Ok(line)) = lines.next() {
-        if no_color {
-          println!("{line}");
-        } else {
-          let colored_line = colorize_log_line(&line, &re);
-          println!("{colored_line}");
+      line_buf.clear();
+      match reader.read_line(&mut line_buf) {
+        Ok(0) => {
+          if was_log_rotated(&file_path, &mut reader) {
+            continue;
+          }
+
+          std::thread::sleep(Duration::from_millis(100));
+        }
+        Ok(_) => {
+          let line = line_buf.trim_end();
+          if no_color {
+            println!("{line}");
+          } else {
+            let colored_line = colorize_log_line(line, &re);
+            println!("{colored_line}");
+          }
+        }
+        Err(_) => {
+          std::thread::sleep(Duration::from_millis(100));
         }
       }
     }
@@ -121,6 +134,20 @@ pub async fn tail_logs(no_color: bool) -> Result<()> {
   .await?
 }
 
+pub(crate) fn was_log_rotated(file_path: &PathBuf, reader: &mut BufReader<File>) -> bool {
+  let current_pos = reader.stream_position().unwrap_or(0);
+  let file_len = fs::metadata(file_path).map(|m| m.len()).unwrap_or(0);
+
+  if file_len < current_pos
+    && let Ok(new_file) = File::open(file_path)
+  {
+    *reader = BufReader::new(new_file);
+    return true;
+  }
+
+  false
+}
+
 fn colorize_log_line(line: &str, re: &Regex) -> String {
   if let Some(caps) = re.captures(line) {
     let level = &caps["level"];

src/utils_tests.rs

@@ -1,8 +1,11 @@
 #[cfg(test)]
 mod tests {
+  use std::fs::{self, File};
+  use std::io::{BufRead, BufReader, Seek, SeekFrom, Write};
+
   use pretty_assertions::assert_eq;
 
-  use crate::utils::{convert_f64_to_gb, convert_runtime, convert_to_gb};
+  use crate::utils::{convert_f64_to_gb, convert_runtime, convert_to_gb, was_log_rotated};
 
   #[test]
   fn test_convert_to_gb() {
@@ -23,4 +26,55 @@ mod tests {
     assert_eq!(hours, 2);
     assert_eq!(minutes, 34);
   }
+
+  #[test]
+  fn test_was_log_rotated_returns_false_when_file_has_not_rotated() {
+    let path = std::env::temp_dir().join("managarr_test_no_rotation.log");
+    fs::write(&path, "line one\nline two\n").unwrap();
+
+    let file = File::open(&path).unwrap();
+    let mut reader = BufReader::new(file);
+    reader.seek(SeekFrom::End(0)).unwrap();
+
+    assert!(!was_log_rotated(&path, &mut reader));
+
+    fs::remove_file(&path).unwrap();
+  }
+
+  #[test]
+  fn test_was_log_rotated_returns_true_and_reopens_reader_after_rotation() {
+    let path = std::env::temp_dir().join("managarr_test_rotation.log");
+    fs::write(&path, "original content that is long enough\n").unwrap();
+
+    let file = File::open(&path).unwrap();
+    let mut reader = BufReader::new(file);
+    reader.seek(SeekFrom::End(0)).unwrap();
+
+    fs::write(&path, "new\n").unwrap();
+
+    assert!(was_log_rotated(&path, &mut reader));
+
+    let mut line = String::new();
+    reader.read_line(&mut line).unwrap();
+    assert_eq!(line, "new\n");
+
+    fs::remove_file(&path).unwrap();
+  }
+
+  #[test]
+  fn test_was_log_rotated_returns_false_when_file_grows() {
+    let path = std::env::temp_dir().join("managarr_test_growing.log");
+    fs::write(&path, "initial\n").unwrap();
+
+    let file = File::open(&path).unwrap();
+    let mut reader = BufReader::new(file);
+    reader.seek(SeekFrom::End(0)).unwrap();
+
+    let mut appender = fs::OpenOptions::new().append(true).open(&path).unwrap();
+    appender.write_all(b"more data\n").unwrap();
+
+    assert!(!was_log_rotated(&path, &mut reader));
+
+    fs::remove_file(&path).unwrap();
+  }
 }