Fix AbstractDateField to correctly show week day names (#10188)

Fixes #9200

client/src/main/java/com/vaadin/client/DateTimeService.java

@@ -96,6 +96,13 @@ public class DateTimeService {
         }
     }
 
+    /**
+     * Returns the localized short name of the specified day.
+     * 
+     * @param day
+     *            the day, {@code 0} is {@code SUNDAY}
+     * @return the localized short name
+     */
     public String getShortDay(int day) {
         try {
             return LocaleService.getShortDayNames(locale)[day];
@@ -105,6 +112,11 @@ public class DateTimeService {
         }
     }
 
+    /**
+     * Returns the first day of the week, according to the used Locale.
+     * 
+     * @return the localized first day of the week, {@code 0} is {@code SUNDAY}
+     */
     public int getFirstDayOfWeek() {
         try {
             return LocaleService.getFirstDayOfWeek(locale);
@@ -114,6 +126,12 @@ public class DateTimeService {
         }
     }
 
+    /**
+     * Returns whether the locale has twelve hour, or twenty four hour clock.
+     * 
+     * @return {@code true} if the locale has twelve hour clock, {@code false}
+     *         for twenty four clock
+     */
     public boolean isTwelveHourClock() {
         try {
             return LocaleService.isTwelveHourClock(locale);
@@ -145,9 +163,16 @@ public class DateTimeService {
         }
     }
 
-    public int getStartWeekDay(Date date) {
-        final Date dateForFirstOfThisMonth = new Date(date.getYear(),
-                date.getMonth(), 1);
+    /**
+     * Returns the first day of week of the specified {@code month}.
+     * 
+     * @param month
+     *            the month, not {@code null}
+     * @return the first day of week,
+     */
+    public int getStartWeekDay(Date month) {
+        final Date dateForFirstOfThisMonth = new Date(month.getYear(),
+                month.getMonth(), 1);
         int firstDay;
         try {
             firstDay = LocaleService.getFirstDayOfWeek(locale);
@@ -158,7 +183,7 @@ public class DateTimeService {
         }
         int start = dateForFirstOfThisMonth.getDay() - firstDay;
         if (start < 0) {
-            start = 6;
+            start += 7;
         }
         return start;
     }

client/src/main/java/com/vaadin/client/ui/VAbstractCalendarPanel.java

@@ -783,10 +783,7 @@ public abstract class VAbstractCalendarPanel<R extends Enum<R>>
         // Print weekday names
         final int firstDay = getDateTimeService().getFirstDayOfWeek();
         for (int i = 0; i < 7; i++) {
-            int day = i + firstDay;
-            if (day > 6) {
-                day = 0;
-            }
+            int day = (i + firstDay) % 7;
             if (isBelowMonth(getResolution())) {
                 days.setHTML(headerRow, firstWeekdayColumn + i, "<strong>"
                         + getDateTimeService().getShortDay(day) + "</strong>");

uitest/src/main/java/com/vaadin/tests/components/datefield/AbstractDateFieldTest.java

@@ -31,7 +31,6 @@ public abstract class AbstractDateFieldTest<T extends AbstractLocalDateField>
                 weekNumberCommand);
         createDateFormatSelectAction(CATEGORY_FEATURES);
         createSetValueAction(CATEGORY_FEATURES);
-
     }
 
     private void createSetValueAction(String category) {
@@ -68,7 +67,6 @@ public abstract class AbstractDateFieldTest<T extends AbstractLocalDateField>
 
         createSelectAction("Date format", category, options, "-",
                 dateFormatCommand);
-
     }
 
     private String getDatePattern(Locale locale, int dateStyle) {

uitest/src/main/java/com/vaadin/tests/components/datefield/DateFieldWeekShortName.java

@@ -0,0 +1,42 @@
+package com.vaadin.tests.components.datefield;
+
+import java.time.LocalDate;
+import java.util.Locale;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.DateField;
+
+public class DateFieldWeekShortName extends AbstractTestUI {
+
+    @Override
+    protected String getTestDescription() {
+        return "DateField to correctly show week name for locales with different first week day";
+    }
+
+    @Override
+    protected Integer getTicketNumber() {
+        return 9200;
+    }
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        LocalDate localDate = LocalDate.of(2017, 10, 20);
+
+        DateField ar = new DateField();
+        ar.setValue(localDate);
+        ar.setLocale(new Locale("ar"));
+        addComponent(ar);
+
+        DateField de = new DateField();
+        de.setLocale(Locale.GERMAN);
+        de.setValue(localDate);
+        addComponent(de);
+
+        DateField en = new DateField();
+        en.setLocale(Locale.ENGLISH);
+        en.setValue(localDate);
+        addComponent(en);
+    }
+
+}

uitest/src/test/java/com/vaadin/tests/components/datefield/DateFieldWeekShortNameTest.java

@@ -0,0 +1,64 @@
+package com.vaadin.tests.components.datefield;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.List;
+
+import org.junit.Test;
+import org.openqa.selenium.By;
+import org.openqa.selenium.WebElement;
+
+import com.vaadin.testbench.elements.DateFieldElement;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+
+public class DateFieldWeekShortNameTest extends MultiBrowserTest {
+
+    @Test
+    public void ar() {
+        // Sat, Sun, Mon, Tue, Wed, Thu, Fri
+        String[] shortWeekDays = { "س", "ح", "ن", "ث", "ر", "خ", "ج" };
+        test(0, 30, shortWeekDays);
+    }
+
+    @Test
+    public void de() {
+        String[] shortWeekDays = { "Mo", "Di", "Mi", "Do", "Fr", "Sa", "So" };
+        test(1, 25, shortWeekDays);
+    }
+
+    @Test
+    public void en() {
+        String[] shortWeekDays = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri",
+                "Sat" };
+        test(2, 1, shortWeekDays);
+    }
+
+    /**
+     * @param index
+     *            the index of the {@link DateFieldElement} to test
+     * @param firstWeekDay
+     *            the day of month of the first day shown in the calendar
+     * @param shortWeekDays
+     *            the names of the short week days
+     */
+    private void test(int index, int firstWeekDay, String[] shortWeekDays) {
+        openTestURL();
+
+        DateFieldElement dateField = $(DateFieldElement.class).get(index);
+        dateField.openPopup();
+
+        WebElement weekDaysRow = getDriver().findElement(
+                By.className("v-datefield-calendarpanel-weekdays"));
+        List<WebElement> weekDays = weekDaysRow
+                .findElements(By.tagName("strong"));
+
+        for (int i = 0; i < shortWeekDays.length; i++) {
+            assertEquals(shortWeekDays[i], weekDays.get(i + 1).getText());
+        }
+
+        WebElement firstWeekDayElement = getDriver().findElement(
+                By.className("v-datefield-calendarpanel-day-offmonth"));
+        assertEquals(String.valueOf(firstWeekDay),
+                firstWeekDayElement.getText());
+    }
+}