Add DateFormat sample UI unit test (#4196)

Author: shai-almog

maven/core-unittests/src/test/java/com/codename1/samples/DateFormatTest2772PortTest.java

@@ -0,0 +1,74 @@
+package com.codename1.samples;
+
+import com.codename1.junit.FormTest;
+import com.codename1.junit.UITestBase;
+import com.codename1.l10n.L10NManager;
+import com.codename1.ui.Button;
+import com.codename1.ui.DisplayTest;
+import com.codename1.ui.Form;
+import com.codename1.ui.Label;
+import com.codename1.ui.layouts.BoxLayout;
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class DateFormatTest2772PortTest extends UITestBase {
+
+    @FormTest
+    void tappingShowDateFormatsUsingLocalizationManager() {
+        Date fixedDate = new Date(1700000000000L);
+        RecordingL10NManager localizationManager = new RecordingL10NManager();
+        implementation.setLocalizationManager(localizationManager);
+
+        Form form = new Form("Test Date Format", BoxLayout.y());
+        Label result = new Label();
+        Button showDate = new Button("Show Date");
+        showDate.addActionListener(evt -> {
+            result.setText(L10NManager.getInstance().formatDateLongStyle(fixedDate));
+            form.revalidateWithAnimationSafety();
+        });
+        form.add(result);
+        form.add(showDate);
+        form.show();
+        ensureSized(showDate, form);
+
+        implementation.tapComponent(showDate);
+        flushSerialCalls();
+        DisplayTest.flushEdt();
+        flushSerialCalls();
+
+        assertEquals("Formatted: 1700000000000", result.getText());
+        assertNotNull(localizationManager.getLastFormattedDate());
+        assertEquals(fixedDate.getTime(), localizationManager.getLastFormattedDate().getTime());
+    }
+
+    private void ensureSized(Button button, Form form) {
+        for (int i = 0; i < 5 && (button.getWidth() <= 0 || button.getHeight() <= 0); i++) {
+            form.revalidate();
+            flushSerialCalls();
+            DisplayTest.flushEdt();
+            flushSerialCalls();
+        }
+    }
+
+    private static class RecordingL10NManager extends L10NManager {
+        private Date lastFormattedDate;
+
+        RecordingL10NManager() {
+            super("en", "US");
+        }
+
+        Date getLastFormattedDate() {
+            return lastFormattedDate;
+        }
+
+        @Override
+        public String formatDateLongStyle(Date date) {
+            lastFormattedDate = date;
+            if (date == null) {
+                return "";
+            }
+            return "Formatted: " + date.getTime();
+        }
+    }
+}