test: expand tests for different LTC framerates

Co-authored-by: aider (gemini/gemini-2.5-pro-preview-05-06) <aider@aider.chat>

src/sync_logic.rs

@@ -312,6 +312,54 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_average_frames_with_different_framerates() {
+        let mut state = LtcState::new();
+        state.record_offset(60); // average jitter is 60ms
+
+        // Test with 25fps
+        state.latest = Some(LtcFrame {
+            status: "LOCK".to_string(),
+            hours: 1,
+            minutes: 1,
+            seconds: 1,
+            frames: 0,
+            frame_rate: 25.0,
+            timestamp: Utc::now(),
+        });
+        // ms_per_frame = 1000.0 / 25.0 = 40ms.
+        // average_frames = round(60 / 40) = round(1.5) = 2 frames
+        assert_eq!(state.average_frames(), 2);
+
+        // Test with 24fps
+        state.latest = Some(LtcFrame {
+            status: "LOCK".to_string(),
+            hours: 1,
+            minutes: 1,
+            seconds: 1,
+            frames: 0,
+            frame_rate: 24.0,
+            timestamp: Utc::now(),
+        });
+        // ms_per_frame = 1000.0 / 24.0 = 41.666...ms
+        // average_frames = round(60 / 41.666) = round(1.44) = 1 frame
+        assert_eq!(state.average_frames(), 1);
+
+        // Test with 29.97fps
+        state.latest = Some(LtcFrame {
+            status: "LOCK".to_string(),
+            hours: 1,
+            minutes: 1,
+            seconds: 1,
+            frames: 0,
+            frame_rate: 29.97,
+            timestamp: Utc::now(),
+        });
+        // ms_per_frame = 1000.0 / 29.97 = 33.366...ms
+        // average_frames = round(60 / 33.366) = round(1.798) = 2 frames
+        assert_eq!(state.average_frames(), 2);
+    }
+
     #[test]
     fn test_ewma_clock_delta() {
         let mut state = LtcState::new();

src/system.rs

@@ -209,6 +209,46 @@ mod tests {
         assert_eq!(target_time.nanosecond(), 920_000_000);
     }
 
+    #[test]
+    fn test_calculate_target_time_different_framerates() {
+        let config = Config::default();
+
+        // 25fps, 12 frames -> 480ms.
+        let mut frame = get_test_frame(10, 20, 30, 12);
+        let target_time_25 = calculate_target_time(&frame, &config);
+        assert_eq!(target_time_25.hour(), 10);
+        assert_eq!(target_time_25.minute(), 20);
+        assert_eq!(target_time_25.second(), 30);
+        assert_eq!(target_time_25.nanosecond(), 480_000_000);
+
+        // 24fps, 12 frames -> 500ms
+        frame.frame_rate = 24.0;
+        let target_time_24 = calculate_target_time(&frame, &config);
+        assert_eq!(target_time_24.hour(), 10);
+        assert_eq!(target_time_24.minute(), 20);
+        assert_eq!(target_time_24.second(), 30);
+        assert_eq!(target_time_24.nanosecond(), 500_000_000);
+
+        // 29.97fps, 15 frames -> 501ms
+        frame.frame_rate = 29.97;
+        frame.frames = 15;
+        // (15 / 29.97) * 1000 = 500.500... -> round() -> 501
+        let target_time_2997 = calculate_target_time(&frame, &config);
+        assert_eq!(target_time_2997.hour(), 10);
+        assert_eq!(target_time_2997.minute(), 20);
+        assert_eq!(target_time_2997.second(), 30);
+        assert_eq!(target_time_2997.nanosecond(), 501_000_000);
+
+        // 30fps, 15 frames -> 500ms
+        frame.frame_rate = 30.0;
+        // frames is still 15
+        let target_time_30 = calculate_target_time(&frame, &config);
+        assert_eq!(target_time_30.hour(), 10);
+        assert_eq!(target_time_30.minute(), 20);
+        assert_eq!(target_time_30.second(), 30);
+        assert_eq!(target_time_30.nanosecond(), 500_000_000);
+    }
+
     #[test]
     fn test_nudge_clock_on_non_linux() {
         #[cfg(not(target_os = "linux"))]