Index: trunk/test/unit/org/openstreetmap/josm/actions/SplitWayActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/actions/SplitWayActionTest.java	(revision 8276)
+++ trunk/test/unit/org/openstreetmap/josm/actions/SplitWayActionTest.java	(revision 8276)
@@ -0,0 +1,96 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.actions;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.openstreetmap.josm.JOSMFixture;
+import org.openstreetmap.josm.Main;
+import org.openstreetmap.josm.data.coor.EastNorth;
+import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.Way;
+import org.openstreetmap.josm.gui.layer.OsmDataLayer;
+
+/**
+ * Unit tests for class SplitWayAction.
+ */
+public final class SplitWayActionTest {
+
+    /** Class under test. */
+    private static SplitWayAction action;
+
+    /**
+     * Setup test.
+     */
+    @BeforeClass
+    public static void setUp() {
+        JOSMFixture.createUnitTestFixture().init(true);
+
+        // Enable "Align in line" feature.
+        action = Main.main.menu.splitWay;
+        action.setEnabled(true);
+    }
+
+    /**
+     * Test case: When node is share by multiple ways, split selected way.
+     * see #11184
+     */
+    @Test
+    public void test11184() throws Exception {
+        DataSet dataSet = new DataSet();
+        OsmDataLayer layer = new OsmDataLayer(dataSet, OsmDataLayer.createNewName(), null);
+
+        Node n1 = new Node(new EastNorth(0, 0));
+        Node n2 = new Node(new EastNorth(-1, 1));
+        Node n3 = new Node(new EastNorth(1, 1));
+        Node n4 = new Node(new EastNorth(-1, -1));
+        Node n5 = new Node(new EastNorth(1, -1));
+        Node n6 = new Node(new EastNorth(-1, 0));
+        Node n7 = new Node(new EastNorth(1, 0));
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(n2);
+        dataSet.addPrimitive(n3);
+        dataSet.addPrimitive(n4);
+        dataSet.addPrimitive(n5);
+        dataSet.addPrimitive(n6);
+        dataSet.addPrimitive(n7);
+
+        Way w1 = new Way();
+        Node[] w1NodesArray = new Node[] {n6, n1, n7};
+        w1.setNodes(Arrays.asList(w1NodesArray));
+        Way w2 = new Way();
+        w2.setNodes(Arrays.asList(new Node[] {n1, n2, n3, n1, n4, n5, n1}));
+        dataSet.addPrimitive(w1);
+        dataSet.addPrimitive(w2);
+
+        dataSet.addSelected(n1);
+        dataSet.addSelected(w2);
+
+        try {
+            Main.main.addLayer(layer);
+            action.actionPerformed(null);
+        } finally {
+            // Ensure we clean the place before leaving, even if test fails.
+            Main.map.mapView.removeLayer(layer);
+        }
+
+        // Ensures 3 ways.
+        assertTrue(String.format("Found %d ways after split action instead of 3.",
+                                 dataSet.getWays().size()),
+                   dataSet.getWays().size() == 3);
+
+        // Ensures way w1 is unchanged.
+        assertTrue("Unselected ways disappear during split action.",
+                   dataSet.getWays().contains(w1));
+        assertTrue("Unselected way seems to have change during split action.",
+                   w1.getNodesCount() == 3);
+        for(int i = 0; i < 3; i++) {
+            assertTrue("Node change in unselected way during split action.",
+                       w1.getNode(i) == w1NodesArray[i]);
+        }
+    }
+}