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A Complete Guide To Unit Testing For Applications

December 7, 2022 1110 Views

Nowadays, unit testing has become an essential part of software testing. It helps you to ensure that each unit of the software is completely functional. It allows you to make better products. But how can you write unit tests? What are the best tools to perform the testing? In this post, you will find all the details. Let’s dive in.

What Is Unit Testing?

What is Unit Testing?

Unit Testing is a type of software testing. It enables you to test individual units or components of an application. It helps you to validate whether the components are showing the expected functionality or not.

The developers perform Unit Testing during the coding phase of an application. It enables you to isolate a section of code to verify its functionality.

Unit tests tend to be easiest when you have a method with input parameters. By analyzing the output, you can determine whether it’s delivering the expected result. However, it can be difficult to create unit tests when a major function interacts with something external to the application.

How To Write Unit Tests?

How To Write Unit Tests

A unit can be a line of code in your program. Also, it can be a method or a class. Generally, smaller units are better for running tests. Because you have to write smaller tests.

Smaller tests give you a clearer view of your code’s performance. It makes things easier for you. Also, small unit tests tend to run fast.

Let’s take a look at a practical example. Here is a sample code for a small unit test in Python:

def divider (a, b)
  return a/b

However, if you are using Ruby, the same test will look like this:

class smallTest < MiniTest::Unit::testCase
  def tiny_test
    assert_equal(3, divider(a, b))

These are simple examples. But it gives you an idea of how small tests make things easier.

Benefits Of Unit Testing

Benefits Of Unit Testing

Unit testing offers several key benefits. Let’s find them out.

  • Enhance The Implementations’ Design: Applying unit testing will force you to think and re-think the design. It helps you to determine what has to be done before you write the code. It enables you to create significantly better designs. Also, you can see an even greater impact by following the TDD approach.
  • Allows Refactoring: Unit testing supports refactoring. Hence, you can easily modify the code without any issues. It can be very useful while updating the features. With easy refactoring, you can confidently change the code to implement necessary changes.
  • Adding Additional Features Without Causing Any Disruptions: Changing already-tested code is risky and costly. You don’t want to create any disruption of service. By running unit tests before implementing the new features, you can ensure the smooth operation of your application.
  • It Helps To Find And Fix Bugs Earlier: By integrating unit testing early in your development process, you can fix bugs before releasing the application. As a result, you will face significantly less technical issues.
  • Act As Documentation: In unit tests, you can find examples of using the code. You can consider them to be documentation or executable specifications.

Read: Things About Angular Material Testing

How to Execute Unit Testing

To execute Unit Tests, you have to write a section of code to test a specific function in the application. Also, you can isolate this function to perform more rigorous testing. It will enable you to eliminate unnecessary dependencies. Generally, developers utilize the UnitTest framework. It helps you to create automated test cases for unit testing.

Unit Testing is of two types. They are:

  • Manual
  • Automated

Usually, developers perform automated unit testing. However, they may go for the manual process when required.

In automated unit testing, you write a section of code to test the function. Once it’s done, you have to comment out the test code. You remove it while deploying the application

Also, you can isolate the function for more rigorous testing. It involves copying and pasting code to its own testing environment. It enables you to discover and eliminate unnecessary dependencies in the code.

Read: UI Testing a Sencha App

Unit Testing Techniques

You can categorize unit testing techniques into three parts. They are Black box testing, White box testing, and Gray box testing.

Black box testing involves validating the user interface, input, and output. In White box testing, you examine the functional behavior of the software application. Finally, you use Gray box testing to execute test suites, test methods, and test cases. It enables you to efficiently perform risk analysis.

Unit Testing utilizes the following code coverage techniques:

  • Statement Coverage
  • Decision Coverage
  • Branch Coverage
  • Condition Coverage
  • Finite State Machine Coverage

Unit Test: Mock Objects

Unit testing relies on mock objects. They are created to test specific code sections that are not yet part of the complete application. They fill in the missing parts of the program.

For example, you have a function. It needs to have variables and objects. However, you haven’t created them yet. Those variables and objects will work as mock objects. You will use them only for testing the particular code section.

Unit Testing Tools

There is plenty of automated unit test software available online. However, which are the best ones? Let’s find them out.

  • Sencha Test: Sencha Test is the best automated testing tool on the market. You can use it to perform both unit testing and end-to-end testing on multiple browsers. Developers use it extensively for testing JS applications. The testing framework has rich APIs to efficiently handle HTML elements.
  • Karma: Karma is one of the most efficient JavaScript command-line tools for spawning web servers.
  • Jest: Jest is a popular unit testing tool. Developers use it for validating JavaScript code and React apps. It helps you to produce more reliable code bases.
  • Mocha: Mocha is a well-known testing utility. Developers use it to test React web applications.
  • Selenium Webdriver: It is the best testing automation tool for creating end-to-end testing scenarios.
  • Jasmine: Jasmine is an open-source testing framework for JavaScript. It has an easy-to-read syntax. It is heavily influenced by other unit testing frameworks, including JSSpec and RSpec.
  • Junit: Junit is a free-to-use testing tool. You can use it with Java programming language. The tool provides assertions to identify the test method. You can use it to efficiently test data.
  • NUnit:  NUnit is a popular unit-testing framework. You can use it for all .NET languages.  NUnit is an open-source tool. It allows you to manually write scripts. Also, it supports data-driven tests, which can run in parallel.

Those are some of the well-known unit testing tools. However, there are plenty of other solutions, especially for C languages and Java. Nonetheless, make sure to find a unit testing tool that meets your programming needs.

Read: 15 Best Automation Testing Tools For Web Applications

Unit Testing Example

Let’s take a look at a Sencha test example. It will help you to practically understand the approach.

Sencha Test Example

Let’s see an example of a Sencha unit testing scenario. Here are the steps:

Step 1

The first step involves generating a case scenario in Sencha Studio.

Step 2

Now, it’s time to create a test class.

Step 3

Next, add a test scenario for the test suite, which we will create in the later stage.

Step 4

Now, the test scenario that you created above will be used for the test scenario.

Step 5

This step involves adding a JavaScript function to test the expected portion of the program or application.

Step 6

Now, you can run the test via a local browser.

Test Driven Development (TDD) & Unit Testing

Unit testing in TDD requires an extensive utilization of testing frameworks. You use a unit test framework to create automated unit tests.

Unit testing frameworks are not unique to TDD. However, they are essential. But what does TDD bring to the world of unit testing? Let’s find them out:

  • TDD relies heavily on testing frameworks
  • The approach tests all classes in the applications
  • It offers quick and easy integration

Unit Testing Best Practices

You may improve the effectiveness of your unit tests by using the following best practices.

Write Readable, Simple Tests

Unit testing helps ensure that your code delivers the intended functionality. However, you have to write simple and readable tests. Otherwise, you won’t be able to understand why a unit fails to pass. Simple tests provide several advantages. For instance, they are easier to write, maintain, and understand. Also, they are easier to refactor.

Deterministic Tests

A non-deterministic test can fail or pass without any code change. As a result, it will be difficult for you to isolate and fix the issue. This is where a deterministic test comes into play. It presents the same behavior as long as the code remains unchanged. Hence, you can conveniently understand and fix the issue.

Unit Tests Should Be Automated

You should strongly consider setting up an automated process for unit testing. You can configure it to make it accessible for all the team members. Hence, everyone can view reports. It enables your team to discuss the relevant metrics, including code coverage and performance.

Isolated Tests

Isolated tests provide more stability. It ensures that you only handle one logic at a time. It makes things easier for you. Also, isolated tests are faster to run.

You can create isolated tests using the test double. It provides a fake version of the component. As a result, you can isolate its behavior within the unit test.

Avoid Active API Calls

You might not need to include specific API calls or other service calls to databases in your tests. If the calls are not engaged, ensure that they are inactive while running the test. You should provide API stubs with the expected behavior and responses. It will enable you to restrict tests to specific units.

Combine Unit And Integration Testing

You can combine unit and integration testing by utilizing the testing pyramid. It’s a popular model that describes the desired test resource distribution. The top of the pyramid consists of end-to-end tests. The middle portion comprises integration tests. And the bottom consists of unit tests.

The testing pyramid offers several key benefits. For instance, it helps you to quickly identify whether a change that you introduced has broken the code or not. Also, it allows you to build a more reliable test suite.


Unit Testing is a type of software testing. It enables you to effectively examine individual units or components.

As you can see, unit testing can be either complex or simple. It depends on several factors, including testing strategies, tools, and philosophies. Unit testing is always necessary for software testing. That is a certainty. Without it, you can’t deliver quality software to the customers. Hence, it’s essential.

Sencha Test enables you to create robust end-to-end and unit tests. It is feature-rich and very easy to use. Try the free trial now to discover its amazing capabilities.


How do I debug unit tests?

To start debugging, you need to set a breakpoint in one or more test methods. They can run in any order. That’s why you have to set breakpoints in all the test methods that you want to debug. If you are using Visual Studio, open Test Explorer. Next, choose the test method. Then select Debug on the right-click menu.

What tool is used for unit testing?

Software developers use Unit Testing tools to examine the components of applications. It helps you to easily identify and fix bugs.

What is a unit test framework?

What are unit test frameworks and how are they used? In simple terms, they are tools to support writing and running unit tests. They provide a foundation for building the examinations. They offer the functionality to execute the tests and report their results.