Along with the clutter, this requires manual intervention by developers to verify the output printed on the console to check if the test ran successfully or not. A better approach is to use assertions which automatically indicate test results. The following StringUtil class is a simple class with one method that concatenates two input strings and returns the result:.
A developer manually needs to verify the output of the test at the console. Some methods do not have a deterministic result, i. For example, consider the following code that has a complex function and a method that calculates the time required in milliseconds for executing the complex function:.
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In this case, each time the calculateTime method is executed, it will return a different value. Writing a test case for this method would not be of any use as the output of the method is variable. Thus, the test method will not be able to verify the output for any particular execution. Often, developers spend a huge amount of time and effort in writing test cases that ensure the application works as expected. However, it is important to test negative test cases as well.
A negative test case is a test case that tests if a system can handle invalid data. For example, consider a simple function which reads an alphanumeric value of length 8, typed by a user. In addition to alphanumeric values, the following negative test cases should be tested:. Similarly, a borderline test case tests if the system works well for extreme values. For example, if a user is expected to enter a numeric value from 1 to , 1 and are the borderline values and it is very important to test the system for these values.
Lasse Koskela - Effective Unit Testing A guide for Java developers (PDF and EPUB)
Ready to get testing? Want to learn more about adding authentication to your webapp or API? Learn more about how Stormpath supports complete Identity Management across the Java and Spring ecosystems in our product documentation , or through any of these great resources:. Types of Software Development Tests Unit tests are used to test individual code components and ensure that code works the way it was intended to.
Use a framework for unit testing Java provides several frameworks that for unit testing.
Some important features of JUnit and TestNG: Easy to setup and run Supports annotations Allows certain tests to be ignored or grouped and executed together Supports parameterized testing, i. Use Test Driven Development — Judiciously! Measure code coverage Code coverage measures in percentage how much of the code is executed when the unit tests are run. Using a tool can improve testing quality, as these tools can point out areas of the code that are untested, allowing you to develop additional tests to cover these areas.
Whenever new functionality is written, immediately write new tests to cover. Ensure that there are test cases that cover all the branches of the code, i. High code coverage does not guarantee the tests are perfect, so beware! Parameters "num". It's a bit different from Udemy and Pluralsight because it's interactive and allows you to run code right from the webpage, which makes it very effective.
Like the previous two courses, this course will also teach you how to write unit tests with JUnit 5, but it also covers topics like why unit tests are important and structure of good unit tests, assertions , assumptions and parameterized tests, and more.
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If you like interactive learning, then you can check out this course; it comes with three free previous lessons and a day return policy, which is good enough to give it a go. Learning JUnit is one thing, but writing unit tests is another. It's easy to write a trivial unit test for a sample project, but when you go into a real project where TDD has not been used and no unit test is written, you will find a lot of challenges when writing your very first test — that's where this course comes in handy. I have purposefully included this course because I believe learning TDD and unit testing, in general, is as important as learning JUnit and Mockito.
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The instructor Matt Greencroft is very experienced and will teach you how to write unit tests for trickier scenarios and show you use TDD techniques to fix applications that weren't developed using TDD. My favorite part of this course is Chapter Handling Legacy Code because this is something a Java developer needs to do in his day-to-day coding. I have learned a lot of good stuff from this course and feel I know unit testing better than before.
Therefore, I highly recommend this course for all Java developers who want to learn unit testing or improve their TDD skills. It nicely complements the previous course and covers things that are not covered in theirs, like PowerMock and DBUnit. Instructor Mike is a solution architect for US Foods and worked in IT for over 15 years, holding roles focused on technical leadership, solution architecture, and enterprise architecture, which means you will learn a lot from his experience. That's all for now on some of the best courses for learning Mockito and JUnit.
I have told my readers to learn unit testing for a long time. I had included this as the first thing in my list of 10 things Java programmer should learn and also shared some free courses to learn JUnit earlier. If you don't have any goals for , make unit testing your top priority this year. It's also worth noting that JUnit 5 tests will run with Java 8 or above, so it's also good to learn Java 8 if you haven't.
Always remember: Writing better unit tests distinguish great programmers from average programmers!
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Thanks a lot for reading! If you like these JUnit 5 online courses, then please share them with your friends and colleagues. If you have any questions or feedback, or you want another course to add in this list, feel free to drop a note. All the best with your unit testing journey! See the original article here.
Effective Unit Testing - AbeBooks - Lasse Koskela:
Over a million developers have joined DZone. Let's be friends:. Those who are new to the game will learn practices that will serve them well for the rest of their career. Lasse Koskela is a coach, trainer, consultant, and programmer. He hacks on open source projects, helps companies improve their productivity, and speaks frequently at conferences around the world.
Lasse is the author of Test Driven, also published by Manning. Effective Unit Testing. Effective Unit Testing A guide for Java developers. Lasse Koskela. A fantastic, definitive guide. It will boost your productivity and deployment effectiveness. Table of Contents takes you straight to the book detailed table of contents. Chapter 1 The promise of good tests 1. State of the union: writing better tests. Chapter 2 In search of good 2. Readable code is maintainable code. Structure helps make sense of things.
Effective Unit Testing
Independent tests run easily in solitude. Every trade has its tools and tests are no exception. Chapter 3 Test doubles 3. The power of a test double. Guidelines for using test doubles. Chapter 4 Readability 4.