Index: trunk/test/unit/org/openstreetmap/josm/tools/StringParserTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/tools/StringParserTest.java	(revision 16181)
+++ trunk/test/unit/org/openstreetmap/josm/tools/StringParserTest.java	(revision 16181)
@@ -0,0 +1,62 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.tools;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Optional;
+
+import net.trajano.commons.testing.UtilityClassTestUtil;
+import org.junit.Test;
+
+/**
+ * Unit tests of {@link StringParser} class.
+ */
+public class StringParserTest {
+
+    /**
+     * Tests that {@code Utils} satisfies utility class criteria.
+     *
+     * @throws ReflectiveOperationException if an error occurs
+     */
+    @Test
+    public void testUtilityClass() throws ReflectiveOperationException {
+        UtilityClassTestUtil.assertUtilityClassWellDefined(Utils.class);
+    }
+
+    /**
+     * Test of {@link StringParser#parse}
+     */
+    @Test
+    public void testParse() {
+        assertThat(StringParser.DEFAULT.parse(char.class, "josm"), is('j'));
+        assertThat(StringParser.DEFAULT.parse(short.class, "123"), is((short) 123));
+        assertThat(StringParser.DEFAULT.parse(int.class, "123456"), is(123456));
+        assertThat(StringParser.DEFAULT.parse(long.class, "1234567890123"), is(1234567890123L));
+        assertThat(StringParser.DEFAULT.tryParse(long.class, "123.456"), is(Optional.empty()));
+        assertThat(StringParser.DEFAULT.tryParse(long.class, "1234567890123"), is(Optional.of(1234567890123L)));
+    }
+
+    /**
+     * Tests that {@link StringParser#DEFAULT} is immutable.
+     */
+    @Test(expected = UnsupportedOperationException.class)
+    public void testDefaultImmutable() {
+        StringParser.DEFAULT.registerParser(String.class, String::valueOf);
+    }
+
+    /**
+     * Tests that {@link StringParser#StringParser(StringParser)} creates a new map.
+     */
+    @Test
+    public void testCopyConstructor() {
+        final StringParser parser = new StringParser(StringParser.DEFAULT).registerParser(boolean.class, "JOSM"::equals);
+        assertTrue(StringParser.DEFAULT.parse(boolean.class, "true"));
+        assertFalse(StringParser.DEFAULT.parse(boolean.class, "JOSM"));
+        assertFalse(parser.parse(boolean.class, "true"));
+        assertTrue(parser.parse(boolean.class, "JOSM"));
+        assertThat(parser.parse(int.class, "123"), is(123));
+    }
+}