ICU4J DateFormatSymbols test to improve coverage.

Bug: 22023363

(cherry picked from commit f0380026d1a7ecc937edca362561a6b6f9d2de4e)

Change-Id: I5b1a649663067a4d5ef4da49058a268a247fa5b8
diff --git a/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/DateFormatSymbolsTest.java b/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/DateFormatSymbolsTest.java
new file mode 100644
index 0000000..2ec40f7
--- /dev/null
+++ b/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/DateFormatSymbolsTest.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed 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 android.icu.cts.coverage.text;
+
+import android.icu.text.DateFormatSymbols;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+@RunWith(JUnit4.class)
+public class DateFormatSymbolsTest {
+    @Test
+    public void testSetEraNames_defensivelyCopies() {
+        DateFormatSymbols symbols = DateFormatSymbols.getInstance();
+        String[] eraNamesInput = new String[]{"longAgo", "notSoLongAgo"};
+        symbols.setEraNames(eraNamesInput);
+        assertArrayEquals(eraNamesInput, symbols.getEraNames());
+        eraNamesInput[0] = "longLongAgo";
+        assertEquals("longAgo", symbols.getEraNames()[0]);
+    }
+
+
+    @Test
+    public void testYearNames_defensivelyCopies() {
+        DateFormatSymbols symbols = DateFormatSymbols.getInstance();
+        String[] yearNamesInput = new String[]{"aYear", "anotherYear"};
+        symbols.setYearNames(
+                yearNamesInput, DateFormatSymbols.FORMAT, DateFormatSymbols.ABBREVIATED);
+        assertArrayEquals(yearNamesInput,
+                symbols.getYearNames(DateFormatSymbols.FORMAT, DateFormatSymbols.ABBREVIATED));
+        yearNamesInput[0] = "aDifferentYear";
+        assertEquals("aYear",
+                symbols.getYearNames(DateFormatSymbols.FORMAT, DateFormatSymbols.ABBREVIATED)[0]);
+    }
+}
diff --git a/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/TestAll.java b/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/TestAll.java
index 20a0e1d..62febe7 100644
--- a/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/TestAll.java
+++ b/android_icu4j/cts-coverage/src/main/tests/android/icu/cts/coverage/text/TestAll.java
@@ -25,6 +25,7 @@
 // Add classes in alphabetical order with a trailing comma even if it's the last entry.
 @Suite.SuiteClasses({
         AlphabeticIndexTest.class,
+        DateFormatSymbolsTest.class,
         RelativeDateTimeFormatterTest.class,
         TimeZoneNamesTest.class,
         UnicodeSetTest.class,