AVA vs JUnit comparison of testing frameworks
What are the differences between AVA and JUnit?

AVA

https://github.com/avajs/ava

JUnit

https://junit.org/junit5/
Programming language

JavaScript

Java

Category

Unit Testing, Intergration Testing

Unit Testing, Regression Testing

General info

Futuristic, new, fast and concurrent JavaScript test runner with simple test syntax

AVA is a test runner for Node.js with a concise API, detailed error output. JS is a single-threaded but Node.JS is a parallel due to it's async behaviour. Ava leverages that and it can run tests concurrently

JUnit is an open source Unit testing framework for java

JUnit is useful for developers to write and run repeatable tests. JUnit has been crucial in the development of test driven development and is partof the xUnit family of unit testing frameworks
xUnit
Set of frameworks originating from SUnit (Smalltalk's testing framework). They share similar structure and functionality.

No

However Ava supports the TAP format which allows us to use the tap-xunit reporter to produce xUnit (JUnit) XML

Yes

It is an instance of the xUnit architecture for unit testing frameworks.
Client-side
Allows testing code execution on the client, such as a web browser

Yes

You can write tests for the DOM with Ava, testing front-end components is easy with Ava

Yes

You can test front-end components such as individual classes and functions that create the front-end
Server-side
Allows testing the bahovior of a server-side code

Yes

Ava utilizes the async I/O nature of Node and runs concurrent tests on NodeJs applications' back-endsA node server can have its endpoints tested with Ava

Yes

You can test classes and functions that compose the back-end such as database connections and so on
Fixtures
Allows defining a fixed, specific states of data (fixtures) that are test-local. This ensures specific environment for a single test

Yes

Using Ava's ava-fixture library it supports fixtures

Yes

JUnit contains a setUp() method, which runs before every test invocation and a tearDown() method, which runs after every test method.
Group fixtures
Allows defining a fixed, specific states of data for a group of tests (group-fixtures). This ensures specific environment for a given group of tests.

Yes

Ava has support for group fixtures

Yes

You can use setUp() and tearDown() inbuilt functions as group fixtures.
Generators
Supports data generators for tests. Data generators generate input data for test. The test is then run for each input data produced in this way.

N/A

You can use JUnit-quickcheck to generate test data
Licence
Licence type governing the use and redistribution of the software

MIT License

Mocks
Mocks are objects that simulate the behavior of real objects. Using mocks allows testing some part of the code in isolation (with other parts mocked when needed)

AVA has no mocking built in, to mock functions you can use third party libraries like Sinon.js.

JUnit does not support mocking internally but you can use a mock framework like Mockito to generate mock objects.
Grouping
Allows organizing tests in groups

No

There is no support for grouping tests

Yes

In JUnit you can create a test suite that bundles a few unit test cases and runs them together. You use both @RunWith and @Suite annotation are used to run the suite test.
Other
Other useful information about the testing framework