Better reporting for string differences

🚀 Feature Proposal

When using toEqual to compare strings (or other iterable structures), when there is a difference between the strings, indicate where the first difference occurred and/or give additional details about the difference.

Motivation

While testing the output of a currency formatting function, I was bamboozled by the following output:

As it turns out, the spaces in the strings are different (breaking x20 vs non-breaking space xA0).

Example

Expected value to equal:
"1 234,57 $"
Received:
"1 234,57 $"
First difference occurred at index 1 : " " does not equal " "

[pedrottimark]

Although the pull request highlights the changed substrings, they still look the same.

A possible future improvement is heuristic to display other invisible characters in addition to:

• U+21B5 ↵ for deleted or inserted line break
• U+00B7 · for space at end of line

[novemberborn]

@SimenB not a heck of a lot, no. The basic idea would be to use control pictures where appropriate, and \u sequences for everything else. That may be annoying with dashes though.

Would love to have a shareable library for this!