Fix timetable generation for StopTimeUpdate containing only arrival or departure

application/src/main/java/org/opentripplanner/model/Timetable.java

@@ -207,7 +207,9 @@ public Result<TripTimesPatch, UpdateError> createUpdatedTripTimesFromGTFSRT(
     StopTimeUpdate update = updates.next();
 
     int numStops = newTimes.getNumStops();
+    @Nullable
     Integer delay = null;
+    @Nullable
     Integer firstUpdatedIndex = null;
 
     final long today = ServiceDateUtils
@@ -246,11 +248,18 @@ public Result<TripTimesPatch, UpdateError> createUpdatedTripTimesFromGTFSRT(
           newTimes.setNoData(i);
         } else {
           // Else the status is SCHEDULED, update times as needed.
-          if (update.hasArrival()) {
+          StopTimeEvent arrival = update.hasArrival() ? update.getArrival() : null;
+          StopTimeEvent departure = update.hasDeparture() ? update.getDeparture() : null;
+
+          // This extra variable is necessary if the departure is specified but the arrival isn't.
+          // We want to propagate the arrival delay from the previous stop, even if the departure
+          // delay at this stop is different.
+          var previousDelay = delay;
+
+          if (arrival != null) {
             if (firstUpdatedIndex == null) {
               firstUpdatedIndex = i;
             }
-            StopTimeEvent arrival = update.getArrival();
             if (arrival.hasDelay()) {
               delay = arrival.getDelay();
               if (arrival.hasTime()) {
@@ -269,15 +278,12 @@ public Result<TripTimesPatch, UpdateError> createUpdatedTripTimesFromGTFSRT(
               );
               return Result.failure(new UpdateError(feedScopedTripId, INVALID_ARRIVAL_TIME, i));
             }
-          } else if (delay != null) {
-            newTimes.updateArrivalDelay(i, delay);
           }
 
-          if (update.hasDeparture()) {
+          if (departure != null) {
             if (firstUpdatedIndex == null) {
               firstUpdatedIndex = i;
             }
-            StopTimeEvent departure = update.getDeparture();
             if (departure.hasDelay()) {
               delay = departure.getDelay();
               if (departure.hasTime()) {
@@ -296,8 +302,38 @@ public Result<TripTimesPatch, UpdateError> createUpdatedTripTimesFromGTFSRT(
               );
               return Result.failure(new UpdateError(feedScopedTripId, INVALID_DEPARTURE_TIME, i));
             }
-          } else if (delay != null) {
-            newTimes.updateDepartureDelay(i, delay);
+          }
+
+          // propagate arrival and departure times, taking care not to cause negative dwells / hops
+          if (arrival == null) {
+            // propagate the delay from the previous stop
+            if (previousDelay != null) {
+              newTimes.updateArrivalDelay(i, previousDelay);
+            }
+            // if the arrival time is later than the departure time, set it to the departure time
+            if (departure != null && newTimes.getArrivalTime(i) > newTimes.getDepartureTime(i)) {
+              newTimes.updateArrivalTime(i, newTimes.getDepartureTime(i));
+            }
+          }
+
+          previousDelay = newTimes.getArrivalDelay(i);
+          if (departure == null) {
+            if (previousDelay < 0) {
+              // if the bus is early, only propagate if it is not a timepoint, otherwise assume that
+              // the bus will wait until the scheduled time
+              if (newTimes.isTimepoint(i)) {
+                newTimes.updateDepartureDelay(i, 0);
+              } else {
+                newTimes.updateDepartureDelay(i, previousDelay);
+              }
+            } else {
+              // the bus is late, depart as soon as it can after the scheduled time
+              newTimes.updateDepartureTime(
+                i,
+                Math.max(newTimes.getArrivalTime(i), newTimes.getScheduledDepartureTime(i))
+              );
+            }
+            delay = newTimes.getDepartureDelay(i);
           }
         }
 

application/src/test/java/org/opentripplanner/model/TimetableTest.java

@@ -312,7 +312,7 @@ public void fixIncoherentTimes() {
     stopTimeUpdateBuilder.setStopSequence(1);
     stopTimeUpdateBuilder.setScheduleRelationship(StopTimeUpdate.ScheduleRelationship.SCHEDULED);
     var stopTimeEventBuilder = stopTimeUpdateBuilder.getArrivalBuilder();
-    stopTimeEventBuilder.setDelay(0);
+    stopTimeEventBuilder.setDelay(900);
     stopTimeUpdateBuilder = tripUpdateBuilder.addStopTimeUpdateBuilder(1);
     stopTimeUpdateBuilder.setStopSequence(2);
     stopTimeUpdateBuilder.setScheduleRelationship(StopTimeUpdate.ScheduleRelationship.SCHEDULED);
@@ -475,7 +475,8 @@ public void testUpdateWithRequiredNoDataDelayPropagationWhenItsNotRequired() {
       assertEquals(0, updatedTripTimes.getArrivalDelay(1));
       assertEquals(0, updatedTripTimes.getDepartureDelay(1));
       assertEquals(-100, updatedTripTimes.getArrivalDelay(2));
-      assertEquals(-100, updatedTripTimes.getDepartureDelay(2));
+      // the stop is a timepoint so the bus will wait until the scheduled time
+      assertEquals(0, updatedTripTimes.getDepartureDelay(2));
       assertTrue(updatedTripTimes.getDepartureTime(1) < updatedTripTimes.getArrivalTime(2));
 
       // REQUIRED_NO_DATA propagation type should always set NO_DATA flags'
@@ -514,7 +515,8 @@ public void testUpdateWithRequiredNoDataDelayPropagationWhenItsRequired() {
       assertEquals(-700, updatedTripTimes.getArrivalDelay(1));
       assertEquals(-700, updatedTripTimes.getDepartureDelay(1));
       assertEquals(-700, updatedTripTimes.getArrivalDelay(2));
-      assertEquals(-700, updatedTripTimes.getDepartureDelay(2));
+      // the stop is a timepoint so the bus will wait until the scheduled time
+      assertEquals(0, updatedTripTimes.getDepartureDelay(2));
       assertTrue(updatedTripTimes.getDepartureTime(1) < updatedTripTimes.getArrivalTime(2));
 
       // REQUIRED_NO_DATA propagation type should always set NO_DATA flags'
@@ -547,13 +549,17 @@ public void testUpdateWithRequiredNoDataDelayPropagationOnArrivalTime() {
       SERVICE_DATE,
       BackwardsDelayPropagationType.REQUIRED_NO_DATA
     );
-    // if arrival time is not defined but departure time is not and the arrival time is greater
-    // than to departure time on a stop, we should not try to fix it by default because the spec
-    // only allows you to drop all estimates for a stop when it's passed according to schedule
-    assertTrue(result.isFailure());
-
-    result.ifFailure(err -> {
-      assertEquals(err.errorType(), NEGATIVE_DWELL_TIME);
+    // the spec does not require you to supply both arrival and departure on a StopTimeUpdate
+    // it says:
+    // either arrival or departure must be provided within a StopTimeUpdate - both fields cannot be
+    // empty
+    // therefore the processing should succeed even if only one of them is given
+    assertTrue(result.isSuccess());
+    result.ifSuccess(p -> {
+      var updatedTripTimes = p.getTripTimes();
+      assertNotNull(updatedTripTimes);
+      assertEquals(15, updatedTripTimes.getArrivalDelay(2));
+      assertEquals(15, updatedTripTimes.getDepartureDelay(2));
     });
   }
 
@@ -586,7 +592,8 @@ public void testUpdateWithRequiredDelayPropagationWhenItsRequired() {
       assertEquals(-700, updatedTripTimes.getArrivalDelay(1));
       assertEquals(-700, updatedTripTimes.getDepartureDelay(1));
       assertEquals(-700, updatedTripTimes.getArrivalDelay(2));
-      assertEquals(-700, updatedTripTimes.getDepartureDelay(2));
+      // the stop is a timepoint so the bus will wait until the scheduled time
+      assertEquals(0, updatedTripTimes.getDepartureDelay(2));
       assertTrue(updatedTripTimes.getDepartureTime(1) < updatedTripTimes.getArrivalTime(2));
 
       // REQUIRED propagation type should never set NO_DATA flags'

application/src/test/java/org/opentripplanner/updater/trip/TripUpdateBuilder.java

@@ -65,6 +65,30 @@ public TripUpdateBuilder addDelayedStopTime(int stopSequence, int delay) {
     return addStopTime(null, -1, stopSequence, delay, delay, DEFAULT_SCHEDULE_RELATIONSHIP, null);
   }
 
+  public TripUpdateBuilder addDelayedArrivalStopTime(int stopSequence, int arrivalDelay) {
+    return addStopTime(
+      null,
+      -1,
+      stopSequence,
+      arrivalDelay,
+      NO_DELAY,
+      DEFAULT_SCHEDULE_RELATIONSHIP,
+      null
+    );
+  }
+
+  public TripUpdateBuilder addDelayedDepartureStopTime(int stopSequence, int departureDelay) {
+    return addStopTime(
+      null,
+      -1,
+      stopSequence,
+      NO_DELAY,
+      departureDelay,
+      DEFAULT_SCHEDULE_RELATIONSHIP,
+      null
+    );
+  }
+
   public TripUpdateBuilder addDelayedStopTime(
     int stopSequence,
     int arrivalDelay,
@@ -166,6 +190,14 @@ private TripUpdateBuilder addStopTime(
       departureBuilder.setDelay(departureDelay);
     }
 
+    if (!arrivalBuilder.hasTime() && !arrivalBuilder.hasDelay()) {
+      stopTimeUpdateBuilder.clearArrival();
+    }
+
+    if (!departureBuilder.hasTime() && !departureBuilder.hasDelay()) {
+      stopTimeUpdateBuilder.clearDeparture();
+    }
+
     return this;
   }
 

application/src/test/java/org/opentripplanner/updater/trip/moduletests/delay/DelayedTest.java

@@ -74,16 +74,18 @@ void singleStopDelay() {
   void complexDelay() {
     var tripInput = TripInput
       .of(TRIP_2_ID)
-      .addStop(STOP_A1, "0:01:00", "0:01:01")
-      .addStop(STOP_B1, "0:01:10", "0:01:11")
-      .addStop(STOP_C1, "0:01:20", "0:01:21")
+      .addStop(STOP_A1, "0:00:00", "0:00:00")
+      .addStop(STOP_B1, "0:05:00", "0:10:00") // 5-minute dwell
+      .addStop(STOP_C1, "0:15:00", "0:16:00")
+      .addStop(STOP_D1, "0:20:00", "0:20:00")
       .build();
     var env = RealtimeTestEnvironment.gtfs().addTrip(tripInput).build();
 
     var tripUpdate = new TripUpdateBuilder(TRIP_2_ID, SERVICE_DATE, SCHEDULED, TIME_ZONE)
       .addDelayedStopTime(0, 0)
-      .addDelayedStopTime(1, 60, 80)
-      .addDelayedStopTime(2, 90, 90)
+      .addDelayedArrivalStopTime(1, 900) // 00:20 arr
+      .addDelayedStopTime(2, 540) // 00:24 arr / 00:25 dep
+      .addDelayedDepartureStopTime(3, 420) // 00:27 dep
       .build();
 
     assertSuccess(env.applyTripUpdate(tripUpdate));
@@ -119,11 +121,11 @@ void complexDelay() {
     );
 
     assertEquals(
-      "SCHEDULED | A1 0:01 0:01:01 | B1 0:01:10 0:01:11 | C1 0:01:20 0:01:21",
+      "SCHEDULED | A1 0:00 0:00 | B1 0:05 0:10 | C1 0:15 0:16 | D1 0:20 0:20",
       env.getScheduledTimetable(TRIP_2_ID)
     );
     assertEquals(
-      "UPDATED | A1 0:01 0:01:01 | B1 0:02:10 0:02:31 | C1 0:02:50 0:02:51",
+      "UPDATED | A1 0:00 0:00 | B1 0:20 0:20 | C1 0:24 0:25 | D1 0:27 0:27",
       env.getRealtimeTimetable(TRIP_2_ID)
     );
   }