JUnit 3
JUnit 3 was the dominant testing framework for Java for many years, but it has several limitations compared to modern alternatives.
JUnit 4
JUnit 4 introduced annotations and removed the need to extend TestCase, which was a major improvement over JUnit 3.
Hamcrest
Hamcrest is a framework for writing matcher objects that can be combined to create flexible expressions of intent.
Spring MockMvc
Spring MockMvc has traditionally used Hamcrest matchers for assertions, which required mixing different assertion styles and was less discoverable.
Old Java versions
Java 13 introduced text blocks (multi-line strings) as a preview feature, finalized in Java 15.