Eager Any.toString() in MatcherResult

[PHaroZ]

kotest version 4.6.0

Hi,

Some of my tests deal with huge data class and I found that they are slow & memory consuming because a lots of matchers indirectly call Any.toString() even if those tests didn't return any error.

An exemple here :

kotest/kotest-assertions/kotest-assertions-core/src/commonMain/kotlin/io/kotest/matchers/nulls/matchers.kt

Line 104 in 0ba1498

return MatcherResult(passed, "Expected value to be null, but was $value.", "Expected value not be null, but was null.")

A simple workarround could be using
io.kotest.matchers.MatcherResult.Companion#invoke(boolean, kotlin.jvm.functions.Function0<java.lang.String>, kotlin.jvm.functions.Function0<java.lang.String>)
instead of
io.kotest.matchers.MatcherResult.Companion#invoke(boolean, java.lang.String, java.lang.String)

The linked example would look like

    return MatcherResult(passed, { "Expected value to be null, but was $value." }, { "Expected value not be null, but was null." })

I could make a PR if you do agree with me.

[sksamuel]

Definitely, good spot.

[sksamuel]

Fixed in master, will be in 5.0.0.M2