Use joda to determine one month from now

api/src/main/java/com/todoroo/andlib/utility/DateUtilities.java

@@ -9,6 +9,7 @@ import android.content.Context;
 import android.text.format.DateFormat;
 import android.text.format.DateUtils;
 
+import org.joda.time.DateTime;
 import org.tasks.api.R;
 
 import java.text.ParseException;
@@ -58,9 +59,14 @@ public class DateUtilities {
 
     /** Returns unixtime one month from now */
     public static long oneMonthFromNow() {
-        Date date = newDate();
-        date.setMonth(date.getMonth() + 1);
-        return date.getTime();
+        final DateTime now = DateTime.now();
+        DateTime result = now.plusMonths(1);
+        // preserving java.util.date behavior
+        int diff = now.getDayOfMonth() - result.getDayOfMonth();
+        if(diff > 0) {
+            result = result.plusDays(diff);
+        }
+        return result.getMillis();
     }
 
     /** Represents a single hour */

astrid/src/test/java/com/todoroo/andlib/utility/DateUtilitiesTest.java

@@ -107,6 +107,16 @@ public class DateUtilitiesTest extends TodorooRobolectricTestCase {
         assertEquals(0, cal.get(Calendar.SECOND));
     }
 
+    @Test
+    public void oneMonthFromStartOfDecember() {
+        DateTime now = new DateTime(2013, 12, 1, 12, 19, 45, 192);
+        final long expected = new DateTime(2014, 1, 1, 12, 19, 45, 192).getMillis();
+
+        freezeAt(now).thawAfter(new Snippet() {{
+            assertEquals(expected, oneMonthFromNow());
+        }});
+    }
+
     @Test
     public void oneMonthFromEndOfDecember() {
         DateTime now = new DateTime(2013, 12, 31, 16, 31, 20, 597);