Add tests for FormBuilderDateRangePicker

Author: nrallakis

test/form_builder_date_range_picker_test.dart

@@ -0,0 +1,105 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_form_builder/flutter_form_builder.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:intl/intl.dart';
+
+import 'form_builder_tester.dart';
+
+void main() {
+  group('FormBuilderDateRangePicker --', () {
+    testWidgets('basic', (WidgetTester tester) async {
+      const widgetName = 'formBuilderDateRangePicker';
+      final testWidget = FormBuilderDateRangePicker(
+        name: widgetName,
+        firstDate: DateTime(2010),
+        // Using last date < today to make date picker always open on 01/01/2010
+        // If last date >= today, it opens on DateTime.now month, which complicates testing.
+        lastDate: DateTime(2020),
+      );
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      expect(formSave(), isTrue);
+      expect(formValue<DateTimeRange?>(widgetName), isNull);
+
+      await tester.tap(find.byType(TextField));
+      await tester.pump();
+
+      // Set Jan 2, 2010 as start
+      await tester.tap(find.text('2').first);
+      await tester.pump();
+
+      // Set Jan 4, 2010 as end
+      await tester.tap(find.text('4').first);
+      await tester.pump();
+
+      // Close date range picker dialog
+      await tester.tap(find.text('SAVE'));
+      await tester.pump();
+
+      expect(formSave(), isTrue);
+      expect(
+        formValue<DateTimeRange?>(widgetName),
+        equals(DateTimeRange(
+          start: DateTime(2010, 1, 2),
+          end: DateTime(2010, 1, 4),
+        )),
+      );
+    });
+
+    testWidgets('initial value', (WidgetTester tester) async {
+      const widgetName = 'formBuilderDateRangePicker';
+      final testWidget = FormBuilderDateRangePicker(
+        name: widgetName,
+        firstDate: DateTime(2010),
+        lastDate: DateTime(2020),
+        initialValue: DateTimeRange(
+          start: DateTime(2010, 1, 2),
+          end: DateTime(2010, 1, 4),
+        ),
+      );
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      expect(formSave(), isTrue);
+      expect(
+        formValue<DateTimeRange?>(widgetName),
+        equals(DateTimeRange(
+          start: DateTime(2010, 1, 2),
+          end: DateTime(2010, 1, 4),
+        )),
+      );
+    });
+
+    testWidgets('text field empty when value is null',
+        (WidgetTester tester) async {
+      const widgetName = 'formBuilderDateRangePicker';
+      final testWidget = FormBuilderDateRangePicker(
+        name: widgetName,
+        firstDate: DateTime(2010),
+        lastDate: DateTime(2020),
+      );
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      expect(find.widgetWithText(TextField, ''), findsOneWidget);
+    });
+
+    testWidgets('text field shows date range', (WidgetTester tester) async {
+      const widgetName = 'formBuilderDateRangePicker';
+      final testWidget = FormBuilderDateRangePicker(
+        name: widgetName,
+        firstDate: DateTime(2010),
+        lastDate: DateTime(2020),
+        initialValue: DateTimeRange(
+          start: DateTime(2010, 1, 2),
+          end: DateTime(2010, 1, 4),
+        ),
+        format: DateFormat('yyyy-MM-dd'),
+      );
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      expect(
+        find.widgetWithText(TextField, '2010-01-02 - 2010-01-04'),
+        findsOneWidget,
+      );
+    });
+  });
+}