Java Junit4: assertEquals for ArrayList<Double> with single precision expected values

Question

I'm writing a JUnit test for a Java variable that is ArrayList<Double> . The complication is that my expected values are single precision whereas Java's Double is double precision. So doing assertEquals(expected_array_list, actual_array_list) does not pass due to precision errors.

My work-around is to iterate over all the elements and assertEquals each pair of doubles, setting the epsilon value to an appropriate value. Is there a method of setting the epsilon for the entire ArrayList , instead of having to decompose it into its elements?

Answer 1

JUnit 4.6 and above has a convenience method assertArrayEquals(double[] expected, double[] actual, double delta) method (with an overloaded variant for a String message, as per the norm). In Java 8, you could convert those List s to primitive arrays pretty easily and just use it:

double delta = 0.05; // or any other reasonable value
double[] expectedArray = 
    expectedList.stream().mapToDouble(Double::doubleValue).toArray();
double[] actualArray = 
    actualList.stream().mapToDouble(Double::doubleValue).toArray();
assertArrayEqulas(expectedArray, actualArray, delta);