How to call assertEquals with Double Epsilon/Precision in Kotlin?

Question

I was wondering, in Kotlin, is there the possibility to call the equivalent of the java method:

assertEquals(double expected, double actual, double precision)

because everytime I'm getting this method instead

assertEquals(expected: T, actual: T, message: String)

And i can't find the one with the precision parameter. Calling the Java one should be fine too I guess.

My call to the method:

assertEquals(5000.00, calculateCouponAmount(basicFaceValue, basicInterestRate, amortizationBullet, couponNumber1), 0.01)

I'm getting an error because 0.01 gets in the "message" field

Can you show your attempted call to the method? Because that should work fine. — diesieben07, Aug 09 '17 at 09:54

Stefano.Maffullo · Accepted Answer · 2017-08-09T15:23:11.043

8

I have figured it out!

This is how it's done

import org.junit.*
import Kotlin.Test.assertEquals

Assert.assertEquals(expected, actual, precision) // to use the jUnit standard one
assertEquals(expected, actual, message) // to use the Kotlin one

edited Aug 09 '17 at 15:23

answered Aug 09 '17 at 10:23

Stefano.Maffullo

801
8
21

1

How does that consider the precision at all in the Kotlin version? – Bruno Medeiros Feb 08 '19 at 11:35
It doesn't in pure Kotlin, that's why you need to use Assert.assertEquals – Stefano.Maffullo Feb 11 '19 at 14:47
7

`// to use the Kotlin one` kind of implies that this is equivalent when it's not, so I think it should be changed – Bruno Medeiros Feb 13 '19 at 06:07
@Stefano.Maffullo it now does. See my answer below for details. – JM Lord Mar 09 '22 at 16:49

score 4 · Answer 2 · answered Mar 05 '20 at 06:18

I couldn't find one, so I created my own set of functions:

import java.math.BigDecimal
import kotlin.math.abs
import kotlin.test.asserter

internal fun assertEquals(expected: Double, actual: Double?, epsilon: Double, message: String? = null) {
    asserter.assertNotNull(null, actual)
    asserter.assertTrue({ messagePrefix(message) + "Expected <$expected>, actual <$actual>, should differ no more than <$epsilon>." },
            abs(expected - actual!!) <= epsilon)
}

internal fun assertEquals(expected: BigDecimal, actual: BigDecimal?, epsilon: Double, message: String? = null) {
    asserter.assertNotNull(null, actual)
    asserter.assertTrue({ messagePrefix(message) + "Expected <$expected>, actual <$actual>, should differ no more than <$epsilon>." },
            (expected - actual!!).abs().toDouble() <= epsilon)
}

internal fun assertEquals(expected: Double, actual: BigDecimal?, epsilon: Double, message: String? = null) {
    asserter.assertNotNull(null, actual)
    asserter.assertTrue({ messagePrefix(message) + "Expected <$expected>, actual <$actual>, should differ no more than <$epsilon>." },
            abs(expected - actual!!.toDouble()) <= epsilon)
}

internal fun messagePrefix(message: String?) = if (message == null) "" else "$message. "

score 2 · Answer 3 · edited Aug 09 '17 at 10:24

2

Just check to make sure you're importing the correct class that has the desired assertEquals method on it. Other than that you may want to verify that the calculateCouponAmount() method returns a Double.

edited Aug 09 '17 at 10:24

Paolo Forgia

6,572
8
46
58

answered Aug 09 '17 at 10:15

John Aqel

31
2
2

score 2 · Answer 4 · answered Feb 18 '22 at 16:06

It is now included in the official API for Double and Float:

fun assertEquals(
    expected: Double,
    actual: Double,
    absoluteTolerance: Double,
    message: String? = null
): Unit

fun assertEquals(
    expected: Float,
    actual: Float,
    absoluteTolerance: Float,
    message: String? = null
): Unit

See https://kotlinlang.org/api/latest/kotlin.test/kotlin.test/assert-equals.html

How to call assertEquals with Double Epsilon/Precision in Kotlin?

4 Answers4