The JUnit framework contains 2 Assert classes (in different packages, obviously) and the methods on each appear to be very similar. Can anybody explain why this is?
The classes I'm referring to are: junit.framework.Assert and org.junit.Assert.
The old method (of JUnit 3) was to mark the test-classes by extending junit.framework.TestCase. That inherited junit.framework.Assert itself and your test class gained the ability to call the assert methods this way.
Since version 4 of JUnit, the framework uses Annotations for marking tests. So you no longer need to extend TestCase. But that means, the assert methods aren't available. But you can make a static import of the new Assert class. That's why all the assert methods in the new class are static methods. So you can import it this way:
import static org.junit.Assert.*;
After this static import, you can use this methods without prefix.
At the redesign they also moved to the new package org.junit that follows better the normal conventions for package naming.
JUnit 3.X: junit.framework.Assert
JUnit 4.X: org.junit.Assert
Prefer the newest one, especially when running JDK5 and higher with annotation support.
There is in fact a functional change: org.junit.Assert will complain if you use the two-argument assertEquals() with float or double, while junit.framework.Assert will silently autobox it.
I believe they are refactoring from junit.framework to org.junit and junit.framework.Assert is maintained for backwards compatibility.
I did a rough source code compare and there are no serious changes. A lot of comments were added in org.junit.Assert and some refactorings are done. The only change is the comparison with Arrays. There are some code cleanups, but there's (imho) no functional change.
In Android Studio (and so in IntelliJ too), you can globally exclude junit.framework from auto-import proposal.
You can set the scope between IDE or Project. If you don't have projects which use JUnit 3 you can safely stay with IDE scope.
Setting position:
Preferences -> Editor -> General -> Auto Import
来源：https://stackoverflow.com/questions/291003/differences-between-2-junit-assert-classes