UIP-2529 Add validateProps method to UiComponent

lib/src/component_declaration/component_base.dart

@@ -131,6 +131,27 @@ abstract class UiComponent<TProps extends UiProps> extends react.Component imple
     );
   }
 
+  /// Throws a [PropError] if [appliedProps] are invalid.
+  ///
+  /// This is called automatically with the latest props available during [componentWillReceiveProps] and
+  /// [componentWillMount], and can also be called manually for custom validation.
+  ///
+  /// Override with a custom implementation to easily add validation (and don't forget to call super!)
+  ///
+  ///     @mustCallSuper
+  ///     void validateProps(Map appliedProps) {
+  ///       super.validateProps(appliedProps);
+  ///
+  ///       var tProps = typedPropsFactory(appliedProps);
+  ///       if (tProps.items.length.isOdd) {
+  ///         throw new PropError.value(tProps.items, 'items', 'must have an even number of items, because reasons');
+  ///       }
+  ///     }
+  @mustCallSuper
+  void validateProps(Map appliedProps) {
+    validateRequiredProps(appliedProps);
+  }
+
   void validateRequiredProps(Map appliedProps) {
     consumedProps?.forEach((ConsumedProps consumedProps) {
       consumedProps.props.forEach((PropDescriptor prop) {
@@ -154,13 +175,13 @@ abstract class UiComponent<TProps extends UiProps> extends react.Component imple
   @override
   @mustCallSuper
   void componentWillReceiveProps(Map newProps) {
-    validateRequiredProps(newProps);
+    validateProps(newProps);
   }
 
   @override
   @mustCallSuper
   void componentWillMount() {
-    validateRequiredProps(props);
+    validateProps(props);
   }
 
   @override

test/over_react/component_declaration/component_base_test.dart

@@ -626,6 +626,42 @@ main() {
         expect(classes.toClassNameBlacklist(), equals('blacklist-1'));
       });
 
+      group('calls validateProps in', () {
+        test('componentWillMount', () {
+          var calls = [];
+          var appliedProps;
+          var initialProps = {
+            'onValidateProps': (Map propsMap) {
+              appliedProps = propsMap;
+              calls.add('onValidateProps');
+            },
+          };
+          component.props = initialProps;
+
+          component.componentWillMount();
+
+          expect(calls, ['onValidateProps']);
+          expect(appliedProps, initialProps);
+        });
+
+        test('componentWillReceiveProps', () {
+          var calls = [];
+          var appliedProps;
+          var newProps = {'key': 'value'};
+          component.props = {
+            'onValidateProps': (Map propsMap) {
+              appliedProps = propsMap;
+              calls.add('onValidateProps');
+            },
+          };
+
+          component.componentWillReceiveProps(newProps);
+
+          expect(calls, ['onValidateProps']);
+          expect(appliedProps, newProps);
+        });
+      });
+
       group('on unmount', () {
         TestComponentComponent component;
         ReactElement instance;
@@ -920,6 +956,13 @@ class TestComponentComponent extends UiComponent<TestComponentProps> {
 
   @override
   TestComponentProps typedPropsFactory(Map propsMap) => new TestComponentProps(propsMap);
+
+  @override
+  void validateProps(Map appliedProps) {
+    super.validateProps(appliedProps);
+
+    if (props['onValidateProps'] != null) props['onValidateProps'](appliedProps);
+  }
 }