feat: add purety check to FormzMixin (#87)

* feat: add purety check to  FormzMixin

* fix: comment typos

Co-authored-by: Alejandro Santiago <dev@alestiago.com>

* fix comment typos

Co-authored-by: Alejandro Santiago <dev@alestiago.com>

* fix comment typos

Co-authored-by: Alejandro Santiago <dev@alestiago.com>

---------

Co-authored-by: Alejandro Santiago <dev@alestiago.com>

Author: Toavina23

lib/formz.dart

@@ -151,6 +151,12 @@ class Formz {
   static bool validate(List<FormzInput<dynamic, dynamic>> inputs) {
     return inputs.every((input) => input.isValid);
   }
+
+  /// Returns a [bool] given a list of [FormzInput] indicating whether
+  /// all the inputs are pure.
+  static bool isPure(List<FormzInput<dynamic, dynamic>> inputs) {
+    return inputs.every((input) => input.isPure);
+  }
 }
 
 /// Mixin that automatically handles validation of all [FormzInput]s present in
@@ -180,6 +186,12 @@ mixin FormzMixin {
   /// Whether the [FormzInput] values are not all valid.
   bool get isNotValid => !isValid;
 
+  /// Whether all of the [FormzInput] are pure.
+  bool get isPure => Formz.isPure(inputs);
+
+  /// Whether all of the [FormzInput] are dirty.
+  bool get isDirty => !isPure;
+
   /// Returns all [FormzInput] instances.
   ///
   /// Override this and give it all [FormzInput]s in your class that should be

test/formz_test.dart

@@ -26,6 +26,18 @@ void main() {
         expect(form.isValid, isTrue);
         expect(form.isNotValid, isFalse);
       });
+
+      test('is pure when none of the inputs were touched', () {
+        final form = NameInputFormzMixin();
+        expect(form.isPure, isTrue);
+        expect(form.isDirty, isFalse);
+      });
+
+      test('is dirty when one or multiple inputs were touched', () {
+        final form = NameInputFormzMixin(name: const NameInput.dirty());
+        expect(form.isDirty, isTrue);
+        expect(form.isPure, isFalse);
+      });
     });
 
     group('FormzInputErrorCacheMixin', () {