How to Test Your Node.js Application?

Node.js is the most used JavaScript library for developing the server-side application in web development. When many developers work upon a big project, continuous changes are being implemented on the same code, thus testing of Node.js application is important. The approach to have smallest errors can be only achieved by various Testing techniques. 

The application of Node.js can be the simple website to the complex structured APIs, this framework of Node.js is used by millions of people. Also, an application is not completed or properly implemented till its testing phase.  

The code in the backend is the main part of an application, thus it needs to be right and bug free. The deploying phase of an application costs business, many millions of dollars. Node.js application reduces the effort of business; thus, it requires to be bug free and in deployable state. 

As a developer, manual testing can cause human error and the code can lose its functionality. The test can be simply done by using the function console.log just to check whether the code is working or not. 

Phases for Testing of Node.js application 

Node.js being the most commonly used framework, holds the more features in terms of testing. Due to this, it is so preferred by the developer nowadays. There are mainly four stages to test an application in Node.js: 

• Unit Testing: This test is used to check for the functionality of the piece of code, this can be done on any of the class or a function. The basic working of this  

• Integration Testing:  This type of testing, software units are grouped together and then the testing is performed. This testing is mainly used to check for the defects within an interface. This can be understood for by if you have exported and imported code in Node.js, this testing will confirm that whether the code worked the say way it was intended. Generally, this type of testing is performed after unit testing. 

• System Testing: This testing is performed on whole of the system to verify that whether if it meets the required needs. 

• Acceptance Testing: This is generally termed as final level of the testing phase; this phase is the last phase and then after it is deployed at consumer end. 

 Definite Examination of testing phases 

Detailed analysis of all the above-mentioned stages of Node.js application testing are as follows with the flowchart of testing: 

Unit Testing 

Unit Testing is a type of an automated Node.js application testing where a developer writes the logic of the code to implement for the testing. This type of Node.js testing can be performed on all type of applications. Knowing about the format of code logic, testing can be achieved for the intended Node.js application.  

The methodology for this type of testing is majorly divided in behavior-driven development and test-driven development. 

Node.js Testing with Unit test by assert module 

The basic working of assert module, which simply checks the condition and, if that condition is not met, it will throw an error. Thus, the Node.js application is considered to be faulty, if fails in testing. 

Let’s go through an example: 

//index.js
function addTwo(a) {
  return a+2; //a normal function
}
function testAddTwo() {
  var x = 5;
  var x2 = x + 2;
  var x3 = addTwo(x);
  console.log (“Expected “+x2+” Got ” + x3);
  if (x2 === x3) {
    return console.log(“Passed”);
  }
  console.log(“Failed”);
}
testAddTwo(); 

Refernce to the code  

Integration Testing 

Integration testing is performed upon a group of single modules, many components or a single piece of module. The aim of this type of testing is to find error when modules are integrated, because it makes module to conflict in between their functionality.  

Testing is the important phase of Node.js application, there are numerous libraries/tools like Karma, Mocha, Jasmine, unit.js etc. 

Testing using Mocha in Integrated mode 

Mocha is the framework for JavaScript testing, so it works on environment of Node and browser. With the feature of good asynchronous operations, makes mocha to stand in front of line of these libraries. 

Hooks in Mocha
describe (‘collection of individual test spec’, function () 

{before (function () {
    // runs before all tests in this block 

}); 

after (function () {
    // runs after all tests in this block
  }); 

beforeEach(function () {
    // runs before each test in this block
  }); 

afterEach(function () {
    // runs after each test in this block
  }); 

// test cases
}); 

System Testing (Source) 

System testing is a software testing that can be performed to evaluate the conformity of the system on an integrated system. The above discussed phases are implemented first i.e., Unit testing and Integrated testing. The input to this testing is the components of the integration testing. Node.js Application system testing detects the errors within both integrated system units and the whole of it.  

Interesting Facts: System Testing is a black-box testing. This testing carries the responsibility for the behavior and design of the developed system and on contrary customer’s expectations. 

Working of the System Testing: System testing is performed as follows: 

• Setup Test Environment: Better quality testing can be achieved after creating the testing environment. 

• Generating Test Case:  Testing process requires the set of the use cases on which the code will provide the outputs. 
• Generating Test Data: Test will take place on the data. 
• Test Case Execution: After performing all above steps, the execution of the test case is performed. 
• Error Reporting: Error in the system is detected in this step. 
• Regression Testing: Side effects of the testing are observed. 

• Defects in Log: All those errors are fixed in this step. 
• Retest: This is the looping process, if the test carried out stands upon the expectations, then its fine, otherwise whole test is repeated again. 

Acceptance Testing

Acceptance Testing mainly focuses upon the acceptability of the Node.js application system. This is the phase of testing where the expectations of the consumer are matched to the developed Node.js application.  

This is the last phase of the testing of Node.js application followed by unit testing, system testing, system testing. This is also used to check for the defects which were missed during the system testing. 

Feedback from the consumer will help to improve the Node.js application functionality. Elimination of the errors arising from the production system testing. 

Wrapping Up  

Node.js Application testing is the crucial part of the deployment of an application. When writing the tests for an application, the developer has to understand that it is just to make the code more efficient and simpler to understand. Above mentioned, Node.js Application testing stages are the way to check for the errors and making it more closely to the consumer expectations.

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