Checking for equality with assertEquals() & Friends

Overview

In this lesson, we'll highlight the importance of assertions for any good testing framework, and introduce the first set of assertion methods provided by JUnit Jupiter. Using assertEquals() and assertSame(), a computational result can be compared against an expected value, and fail its test in case of a mismatch. While assertEquals() compares objects based on their equals() implementation, assertSame() checks references through the == operator. We'll explore a test comparing two objects that fails with assertSame(), but passes when changing to assertEquals().

Furthermore, assertEquals() has various sibling methods, which we'll discover afterwards. These assertions provide very convenient access to checking equality inside collections, arrays, as well as inequality.

Summary

• Your favorite assertion framework still works with JUnit 5
• assertEquals() compares objects
• assertSame() compares object references
• assertArrayEquals() checks each element of two arrays
• assertIterableEquals() checks each element of two iterable collections
• assertNotEquals() and assertNotSame() are the inverse to assertEquals() and assertSame()
• Assertions can be given a message for better logging