Import: empty tracks cannot be imported as TrackStatistics cannot be restored.

#316.

src/androidTest/java/de/dennisguse/opentracks/io/file/importer/LegacyImportTest.java

@@ -83,6 +83,21 @@ public class LegacyImportTest {
         assertTrackpoint(importedTrackPoints.get(5), TrackPoint.Type.TRACKPOINT, "2020-11-28T17:07:20.870Z", 1.234046, 12.340082, 417.99432373046875);
     }
 
+    /**
+     * At least one valid location is required.
+     * Before v3.15.0, Tracks without TrackPoints could be created; such tracks cannot be imported as we cannot restore the TrackStatistics (especially startTime and stopTime).
+     */
+    @LargeTest
+    @Test(expected = ImportParserException.class)
+    public void kml_without_locations() {
+        // given
+        KmlFileTrackImporter trackImporter = new KmlFileTrackImporter(context);
+        InputStream inputStream = InstrumentationRegistry.getInstrumentation().getContext().getResources().openRawResource(de.dennisguse.opentracks.debug.test.R.raw.legacy_kml_empty);
+
+        // when
+        importTrackId = trackImporter.importFile(inputStream);
+    }
+
     /**
      * Check that data that contains pause (lat=100, lng=0) and resume (lat=200, lng=0) locations are restored to a segment break.
      */

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

@@ -29,7 +29,7 @@ public class TrackStatisticsUpdaterTest {
         assertEquals(2.5, statistics.getMinElevation(), 0.01);
         assertEquals(27.5, statistics.getMaxElevation(), 0.01);
         assertEquals(18.0, statistics.getTotalElevationGain(), 0.01);
-        assertEquals(72.0, statistics.getTotalElevationLoss(), 0.01);
+        assertEquals(18.0, statistics.getTotalElevationLoss(), 0.01);
 
         assertEquals(14.226, statistics.getMaxSpeed(), 0.01);
         assertEquals(14.226, statistics.getAverageMovingSpeed(), 0.01);

src/androidTest/res/raw/legacy_kml_empty.kml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<kml xmlns="http://www.opengis.net/kml/2.2"
+xmlns:gx="http://www.google.com/kml/ext/2.2"
+xmlns:atom="http://www.w3.org/2005/Atom"
+xmlns:opentracks="http://opentracksapp.com/xmlschemas/v1">
+<Document>
+<open>1</open>
+<visibility>1</visibility>
+<name><![CDATA[2020-08-24 20:57]]></name>
+<atom:generator><![CDATA[OpenTracks]]></atom:generator>
+<Style id="track">
+<LineStyle><color>7f0000ff</color><width>4</width></LineStyle>
+<IconStyle>
+<scale>1.3</scale>
+<Icon><href>http://earth.google.com/images/kml-icons/track-directional/track-0.png</href></Icon>
+</IconStyle>
+</Style>
+<Style id="start"><IconStyle>
+<scale>1.3</scale>
+<Icon><href>http://maps.google.com/mapfiles/kml/paddle/grn-circle.png</href></Icon>
+<hotSpot x="32" y="1" xunits="pixels" yunits="pixels"/>
+</IconStyle></Style>
+<Style id="end"><IconStyle>
+<scale>1.3</scale>
+<Icon><href>http://maps.google.com/mapfiles/kml/paddle/red-circle.png</href></Icon>
+<hotSpot x="32" y="1" xunits="pixels" yunits="pixels"/>
+</IconStyle></Style>
+<Style id="waypoint"><IconStyle>
+<scale>1.3</scale>
+<Icon><href>http://maps.google.com/mapfiles/kml/pushpin/blue-pushpin.png</href></Icon>
+<hotSpot x="20" y="2" xunits="pixels" yunits="pixels"/>
+</IconStyle></Style>
+<Schema id="schema">
+<gx:SimpleArrayField name="speed" type="float">
+<displayName><![CDATA[Speed (m/s)]]></displayName>
+</gx:SimpleArrayField>
+<gx:SimpleArrayField name="power" type="float">
+<displayName><![CDATA[Power (W)]]></displayName>
+</gx:SimpleArrayField>
+<gx:SimpleArrayField name="cadence" type="float">
+<displayName><![CDATA[Cadence (rpm)]]></displayName>
+</gx:SimpleArrayField>
+<gx:SimpleArrayField name="heart_rate" type="float">
+<displayName><![CDATA[Heart rate (bpm)]]></displayName>
+</gx:SimpleArrayField>
+</Schema>
+<Placemark>
+<name><![CDATA[2020-08-24 20:57]]></name>
+<description><![CDATA[]]></description>
+<icon><![CDATA[UNKNOWN]]></icon>
+<opentracks:trackid>9316e527-a5b8-47c5-bdbd-954b4be7d80e</opentracks:trackid>
+<styleUrl>#track</styleUrl>
+<ExtendedData>
+<Data name="type"><value><![CDATA[unknown]]></value></Data>
+</ExtendedData>
+<gx:MultiTrack>
+<altitudeMode>absolute</altitudeMode>
+<gx:interpolate>1</gx:interpolate>
+</gx:MultiTrack>
+</Placemark>
+</Document>
+</kml>

src/main/java/de/dennisguse/opentracks/io/file/importer/AbstractFileTrackImporter.java

@@ -257,6 +257,9 @@ abstract class AbstractFileTrackImporter extends DefaultHandler implements Track
         for (TrackPoint trackPoint : trackData.bufferedTrackPoints) {
             statistics.addTrackPoint(trackPoint, recordingDistanceInterval);
         }
+        if (!statistics.isTrackInitialized()) {
+            throw new ImportParserException("Track did not contain any locations.");
+        }
         trackData.track.setTrackStatistics(statistics.getTrackStatistics());
 
         Track track = contentProviderUtils.getTrack(trackData.track.getUuid());

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

@@ -97,6 +97,10 @@ public class TrackStatisticsUpdater {
         return stats;
     }
 
+    public boolean isTrackInitialized() {
+        return trackInitialized;
+    }
+
     /**
      * Adds a trackPoint.
      *