Index: trunk/test/unit/org/openstreetmap/josm/gui/mappaint/mapcss/IconRotationTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/mappaint/mapcss/IconRotationTest.java	(revision 18661)
+++ trunk/test/unit/org/openstreetmap/josm/gui/mappaint/mapcss/IconRotationTest.java	(revision 18661)
@@ -0,0 +1,139 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.mappaint.mapcss;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.openstreetmap.josm.data.coor.LatLon;
+import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.IPrimitive;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.OsmUtils;
+import org.openstreetmap.josm.data.osm.Way;
+import org.openstreetmap.josm.gui.mappaint.Environment;
+import org.openstreetmap.josm.gui.mappaint.MultiCascade;
+import org.openstreetmap.josm.gui.mappaint.styleelement.NodeElement;
+import org.openstreetmap.josm.testutils.annotations.BasicPreferences;
+import org.openstreetmap.josm.testutils.annotations.Projection;
+import org.openstreetmap.josm.tools.Utils;
+
+/**
+ * Unit tests of icon-rotation mapcss style property.
+ */
+@BasicPreferences
+@Projection
+class IconRotationTest {
+
+    private DataSet ds;
+
+    private final String CSS_N_WAY_ROTATION = "node { symbol-shape: triangle; icon-rotation: way; }";
+
+    /**
+     * Setup test
+     */
+    @BeforeEach
+    public void setUp() {
+        ds = new DataSet();
+    }
+
+    @Test
+    void testRotationNone() {
+        String css = "node { symbol-shape: triangle; }";
+        Node n = (Node) OsmUtils.createPrimitive("n");
+        ds.addPrimitive(n);
+
+        NodeElement ne = NodeElement.create(createStyleEnv(n, css));
+        assertEquals(0f, ne.mapImageAngle.getRotationAngle(n));
+    }
+
+    @Test
+    void testRotationRad() {
+        String css = "node { symbol-shape: triangle; icon-rotation: 3.14; }";
+        Node n = (Node) OsmUtils.createPrimitive("n");
+        ds.addPrimitive(n);
+
+        NodeElement ne = NodeElement.create(createStyleEnv(n, css));
+        assertEquals(3.14f, ne.mapImageAngle.getRotationAngle(n));
+    }
+
+    @Test
+    void testRotationDeg() {
+        String css = "node { symbol-shape: triangle; icon-rotation: 22.5°; }";
+        Node n = (Node) OsmUtils.createPrimitive("n");
+        ds.addPrimitive(n);
+
+        NodeElement ne = NodeElement.create(createStyleEnv(n, css));
+        assertEquals(Math.PI/8, ne.mapImageAngle.getRotationAngle(n), 0.01);
+    }
+
+    @Test
+    void testRotationWayNoParent() {
+        Node n = (Node) OsmUtils.createPrimitive("n");
+        ds.addPrimitive(n);
+
+        NodeElement ne = NodeElement.create(createStyleEnv(n, CSS_N_WAY_ROTATION));
+        assertEquals(0f, ne.mapImageAngle.getRotationAngle(n));
+    }
+
+    @Test
+    void testRotationWay() {
+        Node n0 = new Node(new LatLon(0.0, 0.2));
+        Node n1 = new Node(new LatLon(-0.1, 0.1));
+        Node n2 = new Node(LatLon.ZERO);
+        Node n3 = new Node(new LatLon(0.0, -0.1));
+        Way w = new Way();
+        w.addNode(n0);
+        w.addNode(n1);
+        w.addNode(n2);
+        w.addNode(n3);
+        ds.addPrimitiveRecursive(w);
+
+        assertEquals(Utils.toRadians(225),
+                     NodeElement.create(createStyleEnv(n0, CSS_N_WAY_ROTATION)).mapImageAngle.getRotationAngle(n0), 
+                     0.01);
+        assertEquals(Utils.toRadians(225),
+                     NodeElement.create(createStyleEnv(n1, CSS_N_WAY_ROTATION)).mapImageAngle.getRotationAngle(n1), 
+                     0.01);
+        assertEquals(Utils.toRadians(-45),
+                     NodeElement.create(createStyleEnv(n2, CSS_N_WAY_ROTATION)).mapImageAngle.getRotationAngle(n2), 
+                     0.01);
+        assertEquals(Utils.toRadians(-90),
+                     NodeElement.create(createStyleEnv(n3, CSS_N_WAY_ROTATION)).mapImageAngle.getRotationAngle(n3), 
+                     0.01);
+    }
+
+    /**
+     * icon-rotation: way; picks first way when a node has multiple parent ways
+     */
+    @Test
+    void testRotationWayMultiple() {
+        Node n = new Node(LatLon.ZERO);
+        Node n1 = new Node(new LatLon(0.1, 0.1));
+        Node n2 = new Node(new LatLon(-0.1, 0.1));
+        Way w1 = new Way();
+        Way w2 = new Way();
+        w1.addNode(n);
+        w1.addNode(n1);
+        w2.addNode(n);
+        w2.addNode(n2);
+        ds.addPrimitiveRecursive(w1);
+        ds.addPrimitiveRecursive(w2);
+
+        assertEquals(Utils.toRadians(45),
+                     NodeElement.create(createStyleEnv(n, CSS_N_WAY_ROTATION)).mapImageAngle.getRotationAngle(n), 
+                     0.01);
+    }
+
+    private Environment createStyleEnv(IPrimitive osm, String css) {
+        MapCSSStyleSource source = new MapCSSStyleSource(css);
+        source.loadStyleSource();
+        Environment env = new Environment(osm, new MultiCascade(), Environment.DEFAULT_LAYER, source);
+
+        for (MapCSSRule r : source.rules) {
+            r.execute(env);
+        }
+
+        return env;
+    }
+}