mrp: handle NaN elapsed time when calculating position

pyatv/protocols/mrp/__init__.py

@@ -210,10 +210,16 @@ def position() -> Optional[int]:
         elapsed_timestamp = state.metadata_field("elapsedTimeTimestamp")
 
         # If we don't have reference time, we can't do anything
-        if not elapsed_timestamp:
+        if not elapsed_timestamp or math.isnan(elapsed_timestamp):
+            return None
+
+        # Both fields are doubles in the protobuf definition and devices do report NaN
+        # for them, which is not convertible to an integer (NaN is also truthy, so "or"
+        # does not help here).
+        elapsed_time: float = state.metadata_field("elapsedTime") or 0.0
+        if math.isnan(elapsed_time):
             return None
 
-        elapsed_time: int = state.metadata_field("elapsedTime") or 0
         diff = (
             datetime.datetime.now() - _cocoa_to_timestamp(elapsed_timestamp)
         ).total_seconds()

tests/protocols/mrp/test_mrp_interface.py

@@ -409,3 +409,18 @@ async def test_metadata_position_calculation(metadata, playing_metadata, player_
         player_state.playback_state = protobuf.PlaybackState.Playing
         playing_metadata["playbackRate"] = 0.0
         assert (await metadata.playing()).position == ELAPSED_TIME
+
+
+async def test_metadata_position_nan(metadata, playing_metadata, player_state):
+    # Devices sometimes report NaN as elapsed time, which cannot be converted to an
+    # integer. Treat it as no position at all instead of raising ValueError.
+    playing_metadata["elapsedTime"] = math.nan
+
+    with faketime("pyatv", NOW_TIME):
+        # Paused state
+        assert (await metadata.playing()).position is None
+
+        # Playing state
+        player_state.playback_state = protobuf.PlaybackState.Playing
+        playing_metadata["playbackRate"] = 1.0
+        assert (await metadata.playing()).position is None