Fixed #1835 - issue with loading non js custom assertion files

lib/api-loader/assertion.js

@@ -1,6 +1,6 @@
 const util = require('util');
 const EventEmitter = require('events');
-const isObject = require('../util/utils.js').isObject;
+const Utils = require('../util/utils.js');
 const NightwatchAssertion = require('../core/assertion.js');
 const BaseCommandLoader = require('./_base-loader.js');
 
@@ -41,7 +41,7 @@ class AssertionLoader extends BaseCommandLoader {
   }
 
   validateModuleDefinition() {
-    if (!(isObject(this.module) && this.module.assertion)) {
+    if (!(Utils.isObject(this.module) && this.module.assertion)) {
       throw new Error('The assertion module needs to contain an .assertion() method');
     }
   }
@@ -94,7 +94,7 @@ class AssertionLoader extends BaseCommandLoader {
   }
 
   runAssertion(passed, value, calleeFn, message) {
-    let expected = typeof this.instance.expected == 'function' ? this.instance.expected() : this.instance.expected;
+    let expected = Utils.isFunction(this.instance.expected) ? this.instance.expected() : this.instance.expected;
 
     this.assertion = NightwatchAssertion.create(passed, {expected, actual: value}, calleeFn, message, this.abortOnFailure, this.stackTrace);
 
@@ -107,7 +107,7 @@ class AssertionLoader extends BaseCommandLoader {
       let value;
       let timeSpent = new Date().getTime() - this.startTime;
 
-      if (typeof this.instance.failure == 'function' && this.instance.failure.call(this.instance, result)) {
+      if (Utils.isFunction(this.instance.failure) && this.instance.failure.call(this.instance, result)) {
         passed = false;
         value = null;
       } else {
@@ -150,18 +150,20 @@ class AssertionLoader extends BaseCommandLoader {
   }
 
   createWrapper(abortOnFailure) {
-    this.validateModuleDefinition();
+    if (this.module) {
+      this.validateModuleDefinition();
 
-    let moduleDefinition = this.module.assertion;
-    this.abortOnFailure = abortOnFailure;
-    let assertion = this;
+      let moduleDefinition = this.module.assertion;
+      this.abortOnFailure = abortOnFailure;
+      let assertion = this;
 
-    this.commandFn = function commandFn(...args) {
-      assertion.stackTrace = commandFn.stackTrace;
-      assertion.createInstance(moduleDefinition, args);
+      this.commandFn = function commandFn(...args) {
+        assertion.stackTrace = commandFn.stackTrace;
+        assertion.createInstance(moduleDefinition, args);
 
-      return assertion.executeCommand();
-    };
+        return assertion.executeCommand();
+      };
+    }
 
     return this;
   }