I know its a year later but you are missing the s on your bottles

Okay. I've changed it to "string".replace("find", "replace");. Does that work better for you?
I was talking about if you just want to use regular strings, the replace doesn't work as expected (replacing all strings with the replace argument).

I have updated the test cases so the expected and actual output both are written in <pre> tags - maybe you should take a look at the whitespace.

Yes, that's certainly one way of doing it. But you'll have to sanitize the find string to make sure it doesn't accidentally do regex-type things. I'll add some tests for this.