Fix bug where parameters of method are not skipped

Author: woutervh-

index.js

@@ -59,6 +59,9 @@ function ValidateClass(errorConstructor = TypeGuardError) {
                 const originalMethod = target.prototype[propertyKey];
                 target.prototype[propertyKey] = function (...args) {
                     for (let i = 0; i < assertions.length; i++) {
+                        if (!assertions[i]) {
+                            continue;
+                        }
                         const errorObject = assertions[i].assertion(args[i]);
                         if (errorObject !== null) {
                             throw new errorConstructor(errorObject, args[i]);

test/issue-75.ts

@@ -0,0 +1,39 @@
+/* tslint:disable:max-classes-per-file */
+
+import * as assert from 'assert';
+import { AssertType, ValidateClass } from '../index';
+
+/* https://github.com/woutervh-/typescript-is/issues/75 */
+
+describe('@ValidateClass, @AssertType', () => {
+    describe('@ValidateClass(), @AssertType() skipping first parameter', () => {
+        @ValidateClass()
+        class TestClass {
+            testMethod(first: string, @AssertType() second: number) {
+                // No op.
+            }
+        }
+        const instance = new TestClass();
+
+        it('should pass validation for as long as the second parameter is a number', () => {
+            instance.testMethod('foo', 0);
+            instance.testMethod('foo', 1);
+            instance.testMethod('foo', Number.NaN);
+            instance.testMethod(false as any, 0);
+            instance.testMethod(false as any, 1);
+            instance.testMethod(false as any, Number.NaN);
+        });
+
+        it('should throw an error for non-numbers passed to the second parameter', () => {
+            const expectedMessageRegExp = /validation failed at second: expected a number, found: .*$/;
+            assert.throws(() => instance.testMethod('foo', '' as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', '0' as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', '1' as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', true as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', false as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', {} as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', [] as any), expectedMessageRegExp);
+            assert.throws(() => instance.testMethod('foo', null as any), expectedMessageRegExp);
+        });
+    });
+});