Index: /trunk/test/unit/org/openstreetmap/josm/gui/mappaint/DividedScaleTest.java
===================================================================
--- /trunk/test/unit/org/openstreetmap/josm/gui/mappaint/DividedScaleTest.java	(revision 17575)
+++ /trunk/test/unit/org/openstreetmap/josm/gui/mappaint/DividedScaleTest.java	(revision 17575)
@@ -0,0 +1,129 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.mappaint;
+
+import org.junit.jupiter.api.Test;
+import org.openstreetmap.josm.tools.Pair;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+/**
+ * Unit tests of {@link DividedScale} class.
+ */
+class DividedScaleTest {
+
+    /**
+     * Test {@link DividedScale#get}
+     */
+    @Test
+    void testGetEmpty() {
+        DividedScale<String> scale = new DividedScale<>();
+        assertThrows(IllegalArgumentException.class, () -> scale.get(0.));
+        assertNull(scale.get(0.01));
+        assertNull(scale.get(1.));
+        assertNull(scale.get(4.));
+        assertNull(scale.get(6.));
+        assertNull(scale.get(8.));
+        assertNull(scale.get(100.));
+    }
+
+    /**
+     * Test {@link DividedScale#put} and {@link DividedScale#get}
+     */
+    @Test
+    void testGetFoo() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.));
+        assertNull(scale.get(1.));
+        assertNull(scale.get(4.));
+        assertEquals("foo", scale.get(4.01));
+        assertEquals("foo", scale.get(6.));
+        assertEquals("foo", scale.get(8.));
+        assertNull(scale.get(8.01));
+        assertNull(scale.get(100.));
+        assertEquals(scale, new DividedScale<>(scale));
+    }
+
+    /**
+     * Test {@link DividedScale#put} and {@link DividedScale#getWithRange}
+     */
+    @Test
+    void testGetWithRangeFoo() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.));
+        Pair<String, Range> pair = scale.getWithRange(6.);
+        assertEquals("foo", pair.a);
+        assertEquals(new Range(4., 8.), pair.b);
+    }
+
+    /**
+     * Test {@link DividedScale#put} and {@link DividedScale#get}
+     */
+    @Test
+    void testGetFooBar() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.))
+                .put("bar", new Range(2., 3.));
+        assertNull(scale.get(2.));
+        assertEquals("bar", scale.get(2.01));
+        assertEquals("bar", scale.get(3.));
+        assertNull(scale.get(3.01));
+        assertNull(scale.get(4.));
+        assertEquals("foo", scale.get(4.01));
+        assertEquals("foo", scale.get(8.));
+        assertNull(scale.get(8.01));
+    }
+
+    /**
+     * Test {@link DividedScale#put} and {@link DividedScale#get}
+     */
+    @Test
+    void testGetFooBarBaz() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.))
+                .put("bar", new Range(2., 3.))
+                .put("baz", new Range(3., 4.));
+        assertNull(scale.get(2.));
+        assertEquals("bar", scale.get(2.01));
+        assertEquals("bar", scale.get(3.));
+        assertEquals("baz", scale.get(3.01));
+        assertEquals("baz", scale.get(4.));
+        assertEquals("foo", scale.get(4.01));
+        assertEquals("foo", scale.get(8.));
+        assertNull(scale.get(8.01));
+    }
+
+    /**
+     * Test {@link DividedScale#put}
+     */
+    @Test
+    void testPutSingleSubrange1() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.));
+        Exception ex = assertThrows(DividedScale.RangeViolatedError.class, () -> scale.put("bar", new Range(4., 9.)));
+        assertEquals("the new range must be within a single subrange (1)", ex.getMessage());
+    }
+
+    /**
+     * Test {@link DividedScale#put}
+     */
+    @Test
+    void testPutSingleSubrangeNoData() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.));
+        Exception ex = assertThrows(DividedScale.RangeViolatedError.class, () -> scale.put("bar", new Range(4., 5.)));
+        assertEquals("the new range must be within a subrange that has no data", ex.getMessage());
+    }
+
+    /**
+     * Test {@link DividedScale#put}
+     */
+    @Test
+    void testPutSingleSubrange2() {
+        DividedScale<String> scale = new DividedScale<String>()
+                .put("foo", new Range(4., 8.));
+        Exception ex = assertThrows(DividedScale.RangeViolatedError.class, () -> scale.put("bar", new Range(2., 5.)));
+        assertEquals("the new range must be within a single subrange (2)", ex.getMessage());
+    }
+}