Adding test cases for StringConverter. Closes x-stream#187.

xstream/src/test/com/thoughtworks/xstream/converters/basic/StringConverterTest.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2020 XStream Committers.
+ * All rights reserved.
+ *
+ * The software in this package is published under the terms of the BSD
+ * style license a copy of which has been included with this distribution in
+ * the LICENSE.txt file.
+ *
+ * Created on 12. Mar 2020 by Zezeng Wang
+ */
+
+package com.thoughtworks.xstream.converters.basic;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import junit.framework.TestCase;
+
+
+/**
+ * Tests {@link StringConverter}.
+ */
+public class StringConverterTest extends TestCase {
+
+    /**
+     * Tests use of own map implementation for cache.
+     */
+    public void testOwnMapImplementationForCache() {
+        // Using the parameter map constructor
+        final Map<String, String> map = new ConcurrentHashMap<>();
+        final StringConverter converter = new StringConverter(map);
+        assertSame(converter.fromString("JUnit"), converter.fromString(new String("JUnit"))); // cached value
+        assertEquals(1, map.size());
+    }
+
+    /**
+     * Tests cache limitation for string length.
+     */
+    public void testCacheLimitationBasedOnStringLength() {
+        // Using the int constructor
+        final StringConverter converter = new StringConverter(4);
+        assertSame(converter.fromString("Test"), converter.fromString(new String("Test"))); // cached value
+        assertNotSame(converter.fromString("JUnit"), converter.fromString(new String("JUnit"))); // non-cached value
+    }
+
+    /**
+     * Tests no cache.
+     */
+    public void testNoCache() {
+        final StringConverter converter = new StringConverter(null);
+        assertNotSame(converter.fromString("JUnit"), converter.fromString(new String("JUnit"))); // non-cached value
+    }
+
+    /**
+     * Tests own map implementation and string length limit for cache.
+     */
+    public void testOwnMapImplementationAndStringLegnthLimitForCache() {
+        // Using the map and int constructor
+        final Map<String, String> map = new ConcurrentHashMap<>();
+        final StringConverter converter = new StringConverter(map, 4);
+        assertSame(converter.fromString("Test"), converter.fromString(new String("Test"))); // cached value
+        assertNotSame(converter.fromString("JUnit"), converter.fromString(new String("JUnit"))); // non-cached value
+        assertEquals(1, map.size());
+    }
+}