implement isInThePast validator

Author: ArturAssisComp

lib/new_api_prototype/datetime_validators.dart

@@ -22,8 +22,8 @@ Validator<DateTime> isAfter(
 }
 
 /// This function returns a validator that checks if the user [DateTime] input is
-/// in the future. If the checking results true, the validator returns `null`.
-/// Otherwise, it returns `isInTheFutureMsg`, if provided, or
+/// in the future (after [DateTime.now]). If the checking results true, the validator
+/// returns `null`. Otherwise, it returns `isInTheFutureMsg`, if provided, or
 /// `FormBuilderLocalizations.current.dateMustBeInTheFutureErrorText`.
 Validator<DateTime> isInTheFuture({
   String? isInTheFutureMsg,
@@ -57,6 +57,21 @@ Validator<DateTime> isBefore(
   };
 }
 
+/// This function returns a validator that checks if the user [DateTime] input is
+/// in the past (before [DateTime.now]). If the checking results true, the validator
+/// returns `null`. Otherwise, it returns `isInThePastMsg`, if provided, or
+/// `FormBuilderLocalizations.current.dateMustBeInThePastErrorText`.
+Validator<DateTime> isInThePast({
+  String? isInThePastMsg,
+}) {
+  return (DateTime value) {
+    return value.isBefore(DateTime.now())
+        ? null
+        : isInThePastMsg ??
+            FormBuilderLocalizations.current.dateMustBeInThePastErrorText;
+  };
+}
+
 String tmpIsDateTimeBetweenErrorMsg(DateTime left, DateTime right) {
   return 'The date must be after ${left.toLocal()} and before ${right.toLocal()}';
 }

test/new_api_testing/datetime_validators/is_in_the_past_validator_test.dart

@@ -0,0 +1,50 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:form_builder_validators/localization/l10n.dart';
+import 'package:form_builder_validators/new_api_prototype/constants.dart';
+import 'package:form_builder_validators/new_api_prototype/datetime_validators.dart';
+
+void main() {
+  group('Validator: isInThePast', () {
+    test('Validation for the current time', () {
+      final DateTime after10Years =
+          DateTime.now().add(const Duration(days: 365));
+      final DateTime after60Seconds =
+          DateTime.now().add(const Duration(seconds: 60));
+      final DateTime before1Year =
+          DateTime.now().subtract(const Duration(days: 365));
+      final DateTime before60Seconds =
+          DateTime.now().subtract(const Duration(seconds: 60));
+      final Validator<DateTime> v = isInThePast();
+      final String errorMsg =
+          FormBuilderLocalizations.current.dateMustBeInThePastErrorText;
+
+      expect(
+        v(after10Years),
+        errorMsg,
+        reason: 'Should return error against now + 10 years',
+      );
+      expect(
+        v(after60Seconds),
+        errorMsg,
+        reason: 'Should return error against now + 60 seconds',
+      );
+      expect(
+        v(before1Year),
+        isNull,
+        reason: 'Should return null against now - 1 year',
+      );
+      expect(
+        v(before60Seconds),
+        isNull,
+        reason: 'Should return null against now - 60 seconds',
+      );
+    });
+
+    test('Should return a custom message after validating', () {
+      const String errorMsg = 'error msg';
+      final Validator<DateTime> v = isInThePast(isInThePastMsg: errorMsg);
+
+      expect(v(DateTime.now().add(const Duration(seconds: 1))), errorMsg);
+    });
+  });
+}