Agile Javaв„ў: Crafting Code with Test-Driven Development

Compile the test. You should expect to see problems,[6] since you have only built the test class StudentTest. StudentTest refers to a class named Student, which is nowhere to be foundyou haven't built it yet!

[6] You may see different errors, depending on your Java compiler and/or IDE.

StudentTest.java:3: cannot find symbol symbol : class Student location: class StudentTest new Student("Jane Doe"); ^ 1 error

Note the position of the caret (^) beneath the statement in error. It indicates that the Java compiler doesn't know what the source text Student represents.

The compile error is expected. Compilation errors are a good thingthey provide you with feedback throughout the development process. One way you can look at a compilation error is as your very first feedback after writing a test. The feedback answers the question: Have you constructed your code using proper Java syntax so that the test can execute?

Simplifying Compilation and Execution

In order to alleviate the tedium of re-executing each of these statements, you may want to build a batch file or script. An example batch file for Windows:

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@echo off javac -cp c:\junit3.8.1\junit.jar *.java if not errorlevel 1 java -cp .;c:\junit3.8.1\junit.jar junit .awtui.TestRunner StudentTest

The batch file does not execute the JUnit test if the compiler returns any compilation errors. A similar script for use under Unix:

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#!/bin/sh javac -classpath "/junit3.8.1/junit.jar" *.java if [ $? -eq 0 ]; then java -cp ".:/junit3.8.1/junit.jar" junit.awtui.TestRunner StudentTest fi

Another option under Unix is to use make, a classic build tool available on most systems. However, an even better solution is a tool called Ant. In Lesson 3, you will learn to use Ant as a cross-platform solution for building and running your tests.

To eliminate the current error, create a new class named Student.java. Edit it to contain the following code:

class Student { }

Run javac again, this time using a wildcard to specify that all source files should be compiled:

javac -cp c:\junit3.8.1\junit.jar *.java

You will receive a new but similar error. Again the compiler cannot find a symbol, but this time it points to the word new in the source text. Also, the compiler indicates that the symbol it's looking for is a constructor that takes a String argument. The compiler found the class Student, but now it needs to know what to do with respect to the "Jane Doe" String.

StudentTest.java:3: cannot find symbol symbol : constructor Student(java.lang.String) location: class Student new Student("Jane Doe"); ^ 1 error

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