Implement elevation gain via barometer.

src/androidTest/java/de/dennisguse/opentracks/services/sensors/ElevationSumManagerTest.java

@@ -0,0 +1,34 @@
+package de.dennisguse.opentracks.services.sensors;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * NOTE: Test data is completely artificial.
+ */
+public class ElevationSumManagerTest {
+
+    private ElevationSumManager elevationSumManager = new ElevationSumManager();
+
+    private static void addSensorValue(ElevationSumManager elevationSumManager, float[] values) {
+        for (float f : values) {
+            elevationSumManager.onSensorValueChanged(f);
+        }
+    }
+
+    @Before
+    public void setUp() {
+        elevationSumManager.reset();
+    }
+
+    @Test
+    public void getElevationGainLoss_downhill() {
+        // then
+        addSensorValue(elevationSumManager, new float[]{1015f, 1015.01f, 1015.02f, 1015.03f, 1015.04f, 1015.05f, 1015.06f, 1015.07f, 1015.08f, 1015.09f, 1015.10f, 1015.11f, 1015.12f, 1015.13f, 1015.14f, 1015.15f});
+
+        // then
+        Assert.assertEquals(0f, elevationSumManager.getElevationGain_m(), 0.01);
+        Assert.assertEquals(-1.08, elevationSumManager.getElevationLoss_m(), 0.01);
+    }
+}