Workaround for GPS week rollover (happening every 19.7 years).

Fixes #155.

https://en.wikipedia.org/wiki/GPS_Week_Number_Rollover

src/androidTest/java/de/dennisguse/opentracks/util/TrackPointUtilsTest.java

@@ -0,0 +1,52 @@
+package de.dennisguse.opentracks.util;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import de.dennisguse.opentracks.content.data.TrackPoint;
+
+public class TrackPointUtilsTest {
+
+    @Test
+    public void fixTime_none() {
+        // given
+        long time = System.currentTimeMillis();
+        TrackPoint trackPoint = new TrackPoint();
+        trackPoint.setTime(time);
+
+        // when
+        TrackPointUtils.fixTime(trackPoint);
+
+        // then
+        Assert.assertEquals(time, trackPoint.getTime());
+    }
+
+    @Test
+    public void fixTime_0() {
+        // given
+        long time = System.currentTimeMillis();
+        TrackPoint trackPoint = new TrackPoint();
+        trackPoint.setTime(0);
+
+        // when
+        TrackPointUtils.fixTime(trackPoint);
+
+        // then
+        Assert.assertEquals(time, trackPoint.getTime(), 1000);
+    }
+
+    @Test
+    public void fixTime_gpsWeekRollover() {
+        // given
+        long time = System.currentTimeMillis();
+        TrackPoint trackPoint = new TrackPoint();
+        trackPoint.setTime(time - 1024 * UnitConversions.ONE_WEEK_MS);
+
+        // when
+        TrackPointUtils.fixTime(trackPoint);
+
+        // then
+        Assert.assertEquals(time, trackPoint.getTime());
+    }
+
+}