问题
I am able to run the sample tests supplied with junit (from any directory). I would think that this suggests my installation of junit is perfectly fine.
I assume, to compile a junit test, it is no different from any other java file, namely: javac fileName.java
My test file (.java and resulting .class) lives in: c:\parent\child. Obviously, in order to compile the .java file, I have a package statement on the first line: package parent.child followed by the all-important: import junit.framework.TestCase; After this, there is a public class fileName definition extends TestCase {}. The file compiles without any warnings or errors.
when I attempt (in the c:\parent\child directory where fileName exists, both the .java and .class):
java org.junit.runner.JUnitCore parent.child.fileName, I get the following: JUnit version 4.1 Could not find class: parent.child.fileName Time: 0 OK (0 tests)
Even if I drop parent.child altogether from the command, it makes no difference.
My CLASSPATH environment variable is set to: c:\parent\junit\junit-4.1.jar;c:\parent\junit;.
If I trying running with -cp c:\ or c:\parent\child or anything else, I still get the error.
回答1:
Java package names are actually part of the class name, and they're also used in a specific way to find *.class files. If Java wants to find a class named parent.child.fileName, it's going to look for a file named parent/child/fileName.class -- i.e., it's going to look for the file in a directory named child in a directory named parent. You have to specify the class path such that the parent directory will be found, something like
java -cp "c:/junit/junit.jar;c:/" org.junit.runner.JUnitCore parent.child.fileName
The class path (-cp) argument has to specify all the places that Java should look for classes, including jar files like junit.jar, which I've imagined is located in a directory called junit. The semicolon ";" is used to separate entries on the class path (assuming you're using Windows; on real computers it's a ":" instead.) The "c:/" entry in the class path is the one that will be used to find the parent directory and thus your class.
回答2:
You should use JUnit Runner to run test outside IDE, not only compile it.
java -cp lib/junit.jar;sw.jar org.junit.runner.JUnitCore your.package.fileName
update this line to yours project structure.
回答3:
In general it's so much easier to run unit tests using a build system like ant/maven/gradle or from within your IDE (IntelliJ/eclipse/Netbeans)
来源：https://stackoverflow.com/questions/15548580/junit-cannot-find-class