Write basic unit test for SystemDefaultsSwitch

src/test/java/org/apache/commons/lang3/test/SystemDefaultsSwitchTest.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.lang3.test;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Locale;
+import java.util.TimeZone;
+
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+
+public class SystemDefaultsSwitchTest {
+
+    private static Locale TEST_DEFAULT_LOCALE;
+    private static Locale DEFAULT_LOCALE_BEFORE_TEST;
+
+    private static TimeZone DEFAULT_TIMEZONE_BEFORE_TEST;
+    private static TimeZone TEST_DEFAULT_TIMEZONE;
+
+    @BeforeClass
+    public static void classSetUp() {
+        DEFAULT_LOCALE_BEFORE_TEST = Locale.getDefault();
+        if (!DEFAULT_LOCALE_BEFORE_TEST.equals(Locale.CANADA)) {
+            Locale.setDefault(Locale.CANADA);
+        } else {
+            // you seem to be from Canada...
+            Locale.setDefault(Locale.CHINESE);
+        }
+        TEST_DEFAULT_LOCALE = Locale.getDefault();
+
+        DEFAULT_TIMEZONE_BEFORE_TEST = TimeZone.getDefault();
+        TimeZone utc = TimeZone.getTimeZone("UTC");
+        if (!DEFAULT_TIMEZONE_BEFORE_TEST.equals(utc)) {
+            TimeZone.setDefault(utc);
+        } else {
+            TimeZone.setDefault(TimeZone.getTimeZone("GMT"));
+        }
+        TEST_DEFAULT_TIMEZONE = TimeZone.getDefault();
+    }
+
+    @Rule
+    public SystemDefaultsSwitch defaultsSwitch = new SystemDefaultsSwitch();
+
+    @Test
+    public void testDefaultLocaleNoAnnotation() throws Exception {
+        assertEquals(TEST_DEFAULT_LOCALE, Locale.getDefault());
+    }
+
+    @Test
+    @SystemDefaults(locale = "en_EN")
+    public void testUseDifferentLocale() throws Exception {
+        assertEquals(new Locale("en", "EN"), Locale.getDefault());
+    }
+
+    @Test
+    public void testDefaultTimeZoneNoAnnotation() throws Exception {
+        assertEquals(TEST_DEFAULT_TIMEZONE, TimeZone.getDefault());
+    }
+
+    @Test
+    @SystemDefaults(timezone = "CET")
+    public void testUseDifferentTimeZone() throws Exception {
+        assertEquals(TimeZone.getTimeZone("CET"), TimeZone.getDefault());
+    }
+
+    @AfterClass
+    public static void classTearDown() {
+        Locale.setDefault(DEFAULT_LOCALE_BEFORE_TEST);
+        TimeZone.setDefault(DEFAULT_TIMEZONE_BEFORE_TEST);
+    }
+}