Setting up Gradle/Java project in IntelliJ IDEA

The main purpose of this book is to teach TDD, so we will not go into detail about Gradle and IntelliJ IDEA. Both are used as an example. All exercises in this book can be done with different choices for IDE and build tools. You can, for example, use Maven and Eclipse instead. For most, it might be easier to follow the same guidelines as those presented throughout the book, but the choice is yours.

The following steps will create a new Gradle project in IntelliJ IDEA:

1. Open IntelliJ IDEA. Click on Create New Project and select Gradle from the left-hand side menu. Then, click on Next.
2. If you are using IDEA 14 and higher, you will be asked for an Artifact ID. Type tdd-java-ch03-tic-tac-toe and click on Next twice. Type tdd-java-ch03-tic-tac-toe as the project name. Then, click on the Finish button:

In the New Project dialog, we can observe that IDEA has already created the build.gradle file. Open it and you'll see that it already contains the JUnit dependency. Since this is our framework of choice in this chapter, there is no additional configuration that we should do. By default, build.gradle is set to use Java 1.5 as a source compatibility setting. You can change it to any version you prefer. The examples in this chapter will not use any of the Java features that came after Version 5, but that doesn't mean that you cannot solve the exercise using, for example, JDK 8.

Our build.gradle file should look like the following:

apply plugin: 'java' 
 
version = '1.0' 
 
repositories { 
  mavenCentral()
} 
 
dependencies { 
  testCompile group: 'junit', name: 'junit', version: '4.11' 
} 

Now, all that's left to do is to create packages that we'll use for tests and the implementation. From the Project dialog, right-click to bring up the Context menu and select New|Directory. Type src/test/java/com/packtpublishing/tddjava/ch03tictactoe and click on the OK button to create the tests package. Repeat the same steps with the src/main/java/com/packtpublishing/tddjava/ch03tictactoe directory to create the implementation package.

Finally, we need to the make test and implementation classes. Create the TicTacToeSpec class inside the com.packtpublishing.tddjava.ch03tictactoe package in the src/test/java directory. This class will contain all our tests. Repeat the same for the TicTacToe class in the src/main/java directory.

Your Project structure should be similar to the one presented in the following screenshot:

The source code can be found in the 00-setup branch of the tdd-java-ch03-tic-tac-toe Git repository at https://bitbucket.org/vfarcic/tdd-java-ch03-tic-tac-toe/branch/00-setup.

That's it. We're set to start working on our Tic-Tac-Toe application using JUnit as the testing framework of choice and Gradle for compilation, dependencies, testing, and other tasks. In Chapter 1, Why Should I Care for Test-Driven Development?, you first encountered the Red-Green-Refactor procedure. Since it is the cornerstone of TDD and is the main objective of the exercise in this chapter, it might be a good idea to go into a bit more detail before we start the development.