Output of encodeResult on strings with dash/negative sign

[LanGit01]

What does this block of code supposed to do? Specifically the invalidYaml function.

https://github.com/substack/tape/blob/0e68b2d1ff44929ea56c291fa24d9083e3151f84/lib/results.js#L148-L154

The invalidYml function returns true on negative numbers because it has a dash. Thus, if the value of ac is -1, instead of printing

actual: -1

It prints

actual: |-
    -1

Is this the expected behavior?

[ljharb]

The implication is that a yaml parser won't work properly with actual: -1, but I'm not sure of the background.