Handling Doubles in ScalaTest

Question

I have just started using ScalaTest and I am using the following to compare two Doubles in my spec as follows:

  it should \"calculate the price\" in {
    v         


        

Answer 1

You can simply do actual shouldBe (expected +- tolerance) if using FlatSpec; other specs have similar matchers instead of shouldBe. It gives better messages in case of failures than assert, and the code is consistent with the other tests.

Answer 2

It looks to me like you've got an implicit instance of Equality[Double] in scope along the lines of org.scalactic.TolerantNumerics, for which the documentation is here.

The example from the doc is:

implicit val doubleEquality = TolerantNumerics.tolerantDoubleEquality(0.01)

But it looks like somebody has instantiated it with a really big tolerance value in your case.

You may also consider trying explicit tolerance by using +-:

assert(x.price() === 185.92 +- 0.01)