JUnit 面试题与答案
问题 6. What CLASSPATH Settings Are Needed to Run JUnit?
You run your JUnit tests from a command line, from an IDE, or from "ant", you must define your CLASSPATH settings correctly. Here is what recommended by the JUnit FAQ with some minor changes:
To run your JUnit tests, you'll need the following elemements in your CLASSPATH:
* The JUnit JAR file should be there.
* Location of your JUnit test classes.
* Location of classes to be tested.
* JAR files of class libraries that are required by classes to be tested.
If found NoClassDefFoundError in your test results, then something is missing from your CLASSPATH.
If you are running your JUnit tests from a command line on a Windows system:
set CLASSPATH=c:\A\junit-4.4.jar;c:\B\test_classes;
c:\B\target_classes;
If you are running your JUnit tests from a command line on a Unix (bash) system:
export CLASSPATH=/A/junit-4.4.jar:/B/test_classes:
/C/target_classes:
问题 7. How Do I Run JUnit Tests from Command Window?
You need to check the following list to run JUnit tests from a command window:
1. Make sure that JDK is installed and the "java" command program is accessible through the PATH setting. Type "java -version" at the command prompt, you should see the JVM reports you back the version string.
2. Make sure that the CLASSPATH is defined as shown in the previous question.
3. Invoke the JUnit runner by entering the following command:
java org.junit.runner.JUnitCore
问题 8. How To Write a JUnit Test Method?
* You need to mark the method as a JUnit test method with the JUnit annotation: @org.junit.Test.
* A JUnit test method must be a "public" method. This allows the runner class to access this method.
* A JUnit test method must be a "void" method. The runner class does not check any return values.
* A JUnit test should perform one JUnit assertion - calling an org.junit.Assert.assertXXX() method.
Here is a simple JUnit test method:
import org.junit.*;
@Test public void testLogin() {
String username = "withoutbook";
Assert.assertEquals("withoutbook", username);
}
问题 9. Why Not Just Use a Debugger for Unit Testing?
* Automated unit testing requires extra time to setup initially. But it will save your time, if your code requires changes many times in the future.
* A debugger is designed for manual debugging and manual unit testing, not for automated unit testing. JUnit is designed for automated unit testing.
问题 10. Why Not Just Write a main() Method for Unit Testing?
You can write a main() method in each class that needs to be tested for unit testing. In the main() method, you could create test object of the class itself, and write some tests to test its methods. However, this is not a recommended approach because of the following points:
* Your classes will be cluttered with test code in main method. All those test codes will be packaged into the final product.
* If you have a lots of classes to test, you need to run the main() method of every class. This requires some extra coding effort.
* If you want the test results to be displayed in a GUI, you will have to write code for that GUI.
* If you want to log the results of tests in HTML format or text format, you will have to write additional code.
* If one method call fails, next method calls won't be executed. You will have to work-around this.
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