How to test for equality of float/double in JUnit?

Question

The assertEquals(double,double) method is justifiably deprecated. Is there an alternate and/or different approach baked into junit - or do I roll my own tiny extension

  static boolean assertEquals(double d1, double d2) {
    return Math.abs(d1 - d2) < 1e-8;
}

Answer 1

是的，请改用assertEquals(double expected, double actual, double delta) 。

Answer 2

In the case of JUnit, there is already made functions.

But in other type of Java code, other than JUnit Test cases, IBM has a recommendation for comparing two floats, using division rather than subtraction - this makes it easier to select an epsilon that works for all ranges of input.

if (abs(a/b - 1) < epsilon)

As for the value of epsilon, I would use 5.96e-08 as given in this Wikipedia table , or perhaps 2x that value.

(see comparing float/double values using == operator )