Test should contain 0 repeats... which makes clear how the spec has gaps.

Repeat 0 should return the original.
Repeat 1 should return the original and a repeat. If I repeat something, it's said twice.

OR

Repeat 0 returns empty string, Repeat 1 returns the original string.

{
expected: '',
actual: 'ho '.repeat(0),
msg: ''ho '.repeat(0) should return an empty string'
},

Pick one:

• Function should return NaN.
• Unit test framework cannot test for NaN.

assertEqual(min("1",1), NaN) should probably not fail for this example...