Index: trunk/test/unit/org/openstreetmap/josm/data/projection/ShiftedProjectionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/projection/ShiftedProjectionTest.java	(revision 10805)
+++ trunk/test/unit/org/openstreetmap/josm/data/projection/ShiftedProjectionTest.java	(revision 10805)
@@ -0,0 +1,148 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.data.projection;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+
+import org.junit.Test;
+import org.openstreetmap.josm.data.ProjectionBounds;
+import org.openstreetmap.josm.data.coor.EastNorth;
+import org.openstreetmap.josm.data.coor.LatLon;
+
+/**
+ * Tests for {@link ShiftedProjecting}
+ * @author Michael Zangl
+ */
+public class ShiftedProjectionTest {
+    private static final class ProjectingBase implements Projecting {
+        @Override
+        public EastNorth latlon2eastNorth(LatLon ll) {
+            return new EastNorth(ll.lat() * 2, ll.lon() * 3);
+        }
+
+        @Override
+        public Map<ProjectionBounds, Projecting> getProjectingsForArea(ProjectionBounds area) {
+            HashMap<ProjectionBounds, Projecting> map = new HashMap<>();
+            // split at east = 0
+            if (area.minEast < 0) {
+                map.put(new ProjectionBounds(area.minEast, area.minNorth, Math.min(area.maxEast, 0), area.maxNorth), this);
+            }
+            if (area.maxEast > 0) {
+                map.put(new ProjectionBounds(Math.max(area.minEast, 0), area.minNorth, area.maxEast, area.maxNorth), this);
+            }
+
+            return map;
+        }
+
+        @Override
+        public Projection getBaseProjection() {
+            throw new AssertionError();
+        }
+
+        @Override
+        public LatLon eastNorth2latlonClamped(EastNorth en) {
+            return new LatLon(en.east() / 2, en.north() / 3);
+        }
+    }
+
+    /**
+     * Test {@link ShiftedProjecting#latlon2eastNorth(LatLon)}
+     */
+    @Test
+    public void testLatlon2eastNorth() {
+        Projecting base = new ProjectingBase();
+
+        ShiftedProjecting unshifted = new ShiftedProjecting(base, new EastNorth(0, 0));
+        EastNorth unshift_00 = unshifted.latlon2eastNorth(new LatLon(0, 0));
+        assertEquals(0, unshift_00.east(), 1e-10);
+        assertEquals(0, unshift_00.north(), 1e-10);
+        EastNorth unshift_12 = unshifted.latlon2eastNorth(new LatLon(1, 2));
+        assertEquals(2, unshift_12.east(), 1e-10);
+        assertEquals(6, unshift_12.north(), 1e-10);
+
+        ShiftedProjecting shifted = new ShiftedProjecting(base, new EastNorth(5, 7));
+        EastNorth shift_00 = shifted.latlon2eastNorth(new LatLon(0, 0));
+        assertEquals(5, shift_00.east(), 1e-10);
+        assertEquals(7, shift_00.north(), 1e-10);
+        EastNorth shift_12 = shifted.latlon2eastNorth(new LatLon(1, 2));
+        assertEquals(2 + 5, shift_12.east(), 1e-10);
+        assertEquals(6 + 7, shift_12.north(), 1e-10);
+    }
+
+    /**
+     * Test {@link ShiftedProjecting#eastNorth2latlonClamped(EastNorth)}
+     */
+    @Test
+    public void testEastNorth2latlonClamped() {
+        Projecting base = new ProjectingBase();
+
+        ShiftedProjecting unshifted = new ShiftedProjecting(base, new EastNorth(0, 0));
+        LatLon unshift_00 = unshifted.eastNorth2latlonClamped(new EastNorth(0, 0));
+        assertEquals(0, unshift_00.lat(), 1e-10);
+        assertEquals(0, unshift_00.lon(), 1e-10);
+        LatLon unshift_12 = unshifted.eastNorth2latlonClamped(new EastNorth(2, 6));
+        assertEquals(1, unshift_12.lat(), 1e-10);
+        assertEquals(2, unshift_12.lon(), 1e-10);
+
+        ShiftedProjecting shifted = new ShiftedProjecting(base, new EastNorth(5, 7));
+        LatLon shift_00 = shifted.eastNorth2latlonClamped(new EastNorth(5, 7));
+        assertEquals(0, shift_00.lat(), 1e-10);
+        assertEquals(0, shift_00.lon(), 1e-10);
+        LatLon shift_12 = shifted.eastNorth2latlonClamped(new EastNorth(2 + 5, 6 + 7));
+        assertEquals(1, shift_12.lat(), 1e-10);
+        assertEquals(2, shift_12.lon(), 1e-10);
+    }
+
+    /**
+     * Test {@link ShiftedProjecting#getProjectingsForArea(ProjectionBounds)}, single area case
+     */
+    @Test
+    public void testGetProjectingsForArea() {
+        Projecting base = new ProjectingBase();
+        ShiftedProjecting shifted = new ShiftedProjecting(base, new EastNorth(5, 7));
+
+        ProjectionBounds area = new ProjectionBounds(10, 0, 20, 20);
+
+        Map<ProjectionBounds, Projecting> areas = shifted.getProjectingsForArea(area);
+        assertEquals(1, areas.size());
+        ProjectionBounds pb = areas.keySet().iterator().next();
+        assertEquals(area.minEast, pb.minEast, 1e-7);
+        assertEquals(area.maxEast, pb.maxEast, 1e-7);
+        assertEquals(area.minNorth, pb.minNorth, 1e-7);
+        assertEquals(area.maxNorth, pb.maxNorth, 1e-7);
+    }
+
+    /**
+     * Test {@link ShiftedProjecting#getProjectingsForArea(ProjectionBounds)}, multiple area case
+     */
+    @Test
+    public void testGetProjectingsForAreaMultiple() {
+        Projecting base = new ProjectingBase();
+        ShiftedProjecting shifted = new ShiftedProjecting(base, new EastNorth(5, 7));
+
+        ProjectionBounds area = new ProjectionBounds(-10, 0, 20, 20);
+
+        // breach is at:
+        EastNorth breachAt = shifted.latlon2eastNorth(base.eastNorth2latlonClamped(new EastNorth(0, 0)));
+        assertEquals(5, breachAt.east(), 1e-7);
+
+        Map<ProjectionBounds, Projecting> areas = shifted.getProjectingsForArea(area);
+        assertEquals(2, areas.size());
+        List<Entry<ProjectionBounds, Projecting>> entries = areas.entrySet().stream()
+                .sorted(Comparator.comparingDouble(b -> b.getKey().minEast)).collect(Collectors.toList());
+        assertEquals(area.minEast, entries.get(0).getKey().minEast, 1e-7);
+        assertEquals(5, entries.get(0).getKey().maxEast, 1e-7);
+        assertEquals(area.minNorth, entries.get(0).getKey().minNorth, 1e-7);
+        assertEquals(area.maxNorth, entries.get(0).getKey().maxNorth, 1e-7);
+        assertEquals(5, entries.get(1).getKey().minEast, 1e-7);
+        assertEquals(area.maxEast, entries.get(1).getKey().maxEast, 1e-7);
+        assertEquals(area.minNorth, entries.get(1).getKey().minNorth, 1e-7);
+        assertEquals(area.maxNorth, entries.get(1).getKey().maxNorth, 1e-7);
+    }
+}