Change: addRule removes previous rule with same name if that exists

Dist/knockout.validation.js

@@ -402,6 +402,12 @@ kv.configuration = configuration;
 		addRule: function (observable, rule) {
 			observable.extend({ validatable: true });
 
+			var existingRule = koUtils.arrayFirst(observable.rules(), function (item) {
+			    return rule.rule === item.rule;
+			});
+			if (existingRule) {
+			    observable.rules.remove(existingRule);
+			}
 			//push a Rule Context to the observables local array of Rule Contexts
 			observable.rules.push(rule);
 			return observable;

Src/api.js

@@ -210,6 +210,12 @@
 		addRule: function (observable, rule) {
 			observable.extend({ validatable: true });
 
+			var existingRule = ko.utils.arrayFirst(observable.rules(), function (item) {
+			    return rule.rule === item.rule;
+			});
+			if (existingRule) {
+			    observable.rules.remove(existingRule);
+			}
 			//push a Rule Context to the observables local array of Rule Contexts
 			observable.rules.push(rule);
 			return observable;

Tests/api-tests.js

@@ -332,6 +332,22 @@ test('validatedObservable is not Valid when not modified', function () {
 
 //#endregion
 
+//#region Adding rules
+
+test("addRule removes previous rule with same name if that exists", function () {
+	var observable = ko.observable();
+	var rulesMutated = false;
+	observable.extend({ validatable: true });
+	ko.validation.addRule(observable, { rule: 'required', params: true });
+	observable.rules.subscribe(function () { rulesMutated = true; });
+	ko.validation.addRule(observable, { rule: 'required', params: false });
+	equal(observable.rules().length, 1);
+	equal(observable.rules()[0].params, false);
+	ok(rulesMutated);
+});
+
+//#endregion
+
 //#region setRules Tests
 module("setRules Tests");