Index: trunk/test/unit/org/openstreetmap/josm/gui/widgets/LargeTextTableTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/widgets/LargeTextTableTest.java	(revision 17788)
+++ trunk/test/unit/org/openstreetmap/josm/gui/widgets/LargeTextTableTest.java	(revision 17788)
@@ -0,0 +1,67 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.widgets;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.awt.Font;
+import java.awt.Rectangle;
+
+import javax.swing.JTable;
+import javax.swing.SwingConstants;
+
+import org.junit.jupiter.api.Test;
+
+class LargeTextTableTest {
+
+    private final JTable table = new LargeTextTable(null, null);
+    private final Rectangle visibleRectangle = new Rectangle(0, 0, 101, 202);
+
+    @Test
+    void testGetScrollableBlockIncrementVertical() {
+        int scrollableBlockIncrement = table.getScrollableBlockIncrement(visibleRectangle, SwingConstants.VERTICAL, 0);
+
+        assertThat(scrollableBlockIncrement, is(202));
+    }
+
+    @Test
+    void testGetScrollableBlockIncrementHorizontal() {
+        int scrollableBlockIncrement = table.getScrollableBlockIncrement(visibleRectangle, SwingConstants.HORIZONTAL, 0);
+
+        assertThat(scrollableBlockIncrement, is(101));
+    }
+
+    @Test
+    void testGetScrollableBlockIncrementWithInvalidOrientation() {
+        assertThrows(IllegalArgumentException.class,
+                () -> table.getScrollableBlockIncrement(visibleRectangle, -11, 0));
+    }
+
+    @Test
+    void testGetScrollableUnitIncrementVertical() {
+        Font font = new Font("", Font.PLAIN, 10);
+        table.setFont(font);
+
+        int actualIncrement = table.getScrollableUnitIncrement(visibleRectangle, SwingConstants.VERTICAL, 0);
+        int expectedIncrement = table.getFontMetrics(font).getHeight();
+
+        assertThat(actualIncrement, is(expectedIncrement));
+    }
+
+    @Test
+    void testGetScrollableUnitIncrementHorizontal() {
+        Font font = new Font("", Font.PLAIN, 10);
+        table.setFont(font);
+
+        int actualIncrement = table.getScrollableUnitIncrement(visibleRectangle, SwingConstants.HORIZONTAL, 0);
+        int expectedIncrement = table.getFontMetrics(font).charWidth('m');
+
+        assertThat(actualIncrement, is(expectedIncrement));
+    }
+
+    @Test
+    void testGetScrollableUnitIncrementWithInvalidOrientation() {
+        assertThrows(IllegalArgumentException.class, () -> table.getScrollableUnitIncrement(visibleRectangle, -11, 0));
+    }
+}