java - Meaning of delta or epsilon argument of assertEquals for double values

Question

I have a question about JUnit assertEquals to test double values. Reading the API doc I can see:

@Deprecated
public static void assertEquals(double expected, double actual)

Deprecated. Use assertEquals(double expected, double actual, double delta) instead.

(Note: in older documentation versions, the delta parameter is called epsilon)

What does the delta (or epsilon) parameter mean?

Answer 1

Epsilon is the value that the 2 numbers can be off by. So it will assert to true as long as Math.abs(expected - actual) <= epsilon