Dragon Dragon - 1 year ago 111
Java Question

How to Assert Two doubles in JUnit Using assertEquals with Epsilon?

assertEquals for doubles is deprecated. I found that the form with Epsilon should be used. It is because of impossible 100% strictness of doubles. But anyway I need to compare two doubles (expected and actual result), but I don't know how to do it.

At the moment my test looks like:

public void testCalcPossibleDistancePercentageCount() {
int percentage = 100;
assertEquals("Wrong max possible value for %" + percentage, 110.42, processor.calcPossibleValue(percentage));
percentage = 75;
/*corresponding assertions*/

Here are 3 double values I receive and which I want to check with JUnit: 110.42, 2760.5 and 10931.58.
How should JUnit test look like with assertions for them? I receive them as a result of calculation in a method:

processor.calcPossibleValue(allowed_percentage){return /*Some weird formulae here*/;}

Answer Source

You need to add a fourth parameter to the assertEquals call: the threshold within which two doubles should be considered "equal". Your call should look like this:

assertEquals("Wrong max possible value for %" + percentage, 110.42,
        processor.calcPossibleValue(percentage), 0.01);

The above call would indicate that if the value returned by processor.calcPossibleValue(percentage) is within ± 0.01 of 110.42, then the two values are considered equal. You can change this value to make it as small as is necessary for your application.

See the JUnit documentation for more information.

Recommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download