Merge "Document some surprising GregorianCalendar behavior."

2 files changed, 66 insertions, 2 deletions

diff --git a/luni/src/main/java/java/util/GregorianCalendar.java b/luni/src/main/java/java/util/GregorianCalendar.java
index 9ff9ccc..df6d772 100644
--- a/luni/src/main/java/java/util/GregorianCalendar.java
+++ b/luni/src/main/java/java/util/GregorianCalendar.java
@@ -670,8 +670,16 @@ public class GregorianCalendar extends Calendar {
         if (useMonth
                 && (lastDateFieldSet == DAY_OF_WEEK || lastDateFieldSet == WEEK_OF_YEAR)) {
             if (isSet[WEEK_OF_YEAR] && isSet[DAY_OF_WEEK]) {
-                useMonth = lastDateFieldSet != WEEK_OF_YEAR && weekMonthSet
-                        && isSet[DAY_OF_WEEK];
+                if (lastDateFieldSet == WEEK_OF_YEAR) {
+                    useMonth = false;
+                } else if (lastDateFieldSet == DAY_OF_WEEK) {
+                    // DAY_OF_WEEK belongs to both the Month + Week + Day and the
+                    // WeekOfYear + Day combinations. We're supposed to use the most
+                    // recent combination, as specified by the single set field. We can't
+                    // know for sure in this case, so we always prefer the week-month-day
+                    // combination if week-month is already set.
+                    useMonth = weekMonthSet;
+                }
             } else if (isSet[DAY_OF_YEAR]) {
                 useMonth = isSet[DATE] && isSet[MONTH];
             }
diff --git a/luni/src/test/java/libcore/java/util/GregorianCalendarTest.java b/luni/src/test/java/libcore/java/util/GregorianCalendarTest.java
new file mode 100644
index 0000000..b2c50b2
--- /dev/null
+++ b/luni/src/test/java/libcore/java/util/GregorianCalendarTest.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2013 Google Inc.
+ *
+ * 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 libcore.java.util;
+
+
+import junit.framework.TestCase;
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+
+public class GregorianCalendarTest extends TestCase {
+
+    // https://code.google.com/p/android/issues/detail?id=61993
+    public void test_computeFields_dayOfWeekAndWeekOfYearSet() {
+        Calendar greg = GregorianCalendar.getInstance();
+
+        // Setting WEEK_OF_YEAR and DAY_OF_WEEK with an intervening
+        // call to computeFields will work.
+        greg.set(Calendar.WEEK_OF_YEAR, 1);
+        assertEquals(1, greg.get(Calendar.WEEK_OF_YEAR));
+        greg.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
+        assertEquals(1, greg.get(Calendar.WEEK_OF_YEAR));
+
+        // Setting WEEK_OF_YEAR after DAY_OF_WEEK with no intervening
+        // call to computeFields will work.
+        greg = GregorianCalendar.getInstance();
+        greg.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
+        greg.set(Calendar.WEEK_OF_YEAR, 1);
+        assertEquals(1, greg.get(Calendar.WEEK_OF_YEAR));
+        assertEquals(Calendar.MONDAY, greg.get(Calendar.DAY_OF_WEEK));
+
+        // Setting DAY_OF_WEEK *after* WEEK_OF_YEAR with no intervening computeFields
+        // will make WEEK_OF_YEAR have no effect. This is a limitation of the API.
+        // Combinations are chosen based *only* on the value of the last field set,
+        // which in this case is DAY_OF_WEEK.
+        greg = GregorianCalendar.getInstance();
+        int weekOfYear = greg.get(Calendar.WEEK_OF_YEAR);
+        greg.set(Calendar.WEEK_OF_YEAR, 1);
+        greg.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
+        // Unchanged WEEK_OF_YEAR.
+        assertEquals(weekOfYear, greg.get(Calendar.WEEK_OF_YEAR));
+    }
+}