Bugfix: TrackStatisticsUpdater was computing distance incorrectly.

While using a cycling speed and distance sensor, the updater was not using the distance from the most recent trackpoint but rather the one considered last moving.

Fixes #762.

src/androidTest/java/de/dennisguse/opentracks/content/data/TrackPointTest.java

@@ -1,10 +1,13 @@
 package de.dennisguse.opentracks.content.data;
 
+import android.location.Location;
+
 import org.junit.Test;
 
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -25,4 +28,35 @@ public class TrackPointTest {
 
         assertFalse(tp.isRecent());
     }
+
+    @Test
+    public void distanceToPrevious() {
+        Location l1 = new Location("test");
+        l1.setLatitude(0);
+        l1.setLongitude(0.0001);
+        TrackPoint tp1 = new TrackPoint(l1);
+
+        Location l2 = new Location("test");
+        l2.setLatitude(0);
+        l2.setLongitude(0.0002);
+        TrackPoint tp2 = new TrackPoint(l2);
+
+        // without sensor distance
+        assertEquals(11.13, tp2.distanceToPrevious(tp1).toM(), 0.01);
+
+        // tp1 has sensor distance
+        tp1.setSensorDistance(Distance.of(5));
+        tp1.setSensorDistance(null);
+        assertEquals(11.13, tp2.distanceToPrevious(tp1).toM(), 0.01);
+
+        // tp2 has sensor distance
+        tp1.setSensorDistance(null);
+        tp2.setSensorDistance(Distance.of(5));
+        assertEquals(5, tp2.distanceToPrevious(tp1).toM(), 0.01);
+
+        // tp1 and tp2 have sensor distance
+        tp1.setSensorDistance(Distance.of(10));
+        tp2.setSensorDistance(Distance.of(5));
+        assertEquals(5, tp2.distanceToPrevious(tp1).toM(), 0.01);
+    }
 }

src/androidTest/java/de/dennisguse/opentracks/stats/TrackStatisticsUpdaterTest.java

@@ -146,6 +146,34 @@ public class TrackStatisticsUpdaterTest {
         assertEquals(15, subject.getTrackStatistics().getTotalDistance().toM(), 0.01);
     }
 
+    @Test
+    public void addTrackPoint_distance_from_GPS_moving_and_sensor_disconnecting() {
+        // given
+        TrackStatisticsUpdater subject = new TrackStatisticsUpdater();
+
+        TrackPoint tp1 = new TrackPoint(TrackPoint.Type.SEGMENT_START_MANUAL, Instant.ofEpochMilli(1000));
+        TrackPoint tp2 = new TrackPoint(0, 0, Altitude.WGS84.of(5.0), Instant.ofEpochMilli(2000));
+        TrackPoint tp3 = new TrackPoint(0.00001, 0, Altitude.WGS84.of(5.0), Instant.ofEpochMilli(3000));
+        tp3.setSensorDistance(Distance.of(5f));
+        TrackPoint tp4 = new TrackPoint(0.0005, 0, Altitude.WGS84.of(5.0), Instant.ofEpochMilli(4000));
+        TrackPoint tp5 = new TrackPoint(TrackPoint.Type.SEGMENT_END_MANUAL, Instant.ofEpochMilli(5000));
+
+        // when
+        subject.addTrackPoint(tp1, GPS_DISTANCE);
+        subject.addTrackPoint(tp2, GPS_DISTANCE);
+        subject.addTrackPoint(tp3, GPS_DISTANCE);
+
+        // then
+        assertEquals(5, subject.getTrackStatistics().getTotalDistance().toM(), 0.01);
+
+        // when
+        subject.addTrackPoint(tp4, GPS_DISTANCE);
+        subject.addTrackPoint(tp5, GPS_DISTANCE);
+
+        // then
+        assertEquals(59.18, subject.getTrackStatistics().getTotalDistance().toM(), 0.01);
+    }
+
     @Ignore("TODO: create a concept ont to compute speed from GPS and sensor")
     @Test
     public void addTrackPoint_speed_from_GPS_not_moving() {

src/main/java/de/dennisguse/opentracks/stats/TrackStatisticsUpdater.java

@@ -159,7 +159,7 @@ public class TrackStatisticsUpdater {
 
         if (!trackPoint.hasSensorDistance()) {
             // GPS-based distance/speed
-            Distance movingDistance = lastMovingTrackPoint.distanceToPrevious(trackPoint);
+            Distance movingDistance = trackPoint.distanceToPrevious(lastMovingTrackPoint);
             if (movingDistance.lessThan(minGPSDistance) && !trackPoint.isMoving()) {
                 speedBuffer_mps.reset();
                 lastTrackPoint = trackPoint;