Most, if not all, currency formats in CLDR use a non-breaking space between the currency and the amount. This is, I think, correct because it would be potentially confusing if a word or line wrap were to occur between the two parts of the string.

If you really want to force a space than you can define your own format like:

# Note this is forcing a breaking space, 0x20
iex> Money.to_string!(Money.new(:AED, 1234), format: "¤ #,###.00")
"AED 1,234.00"
iex> Money.to_string!(Money.new(:AED, 1234), format: "¤ #,###.00") == "AED 1,234.00"
true

However I don’t recommend it for a few reasons:

1. Not all currencies follow that format. They have variable number of decimal places. Some formats don’t have a space between the currency symbol and the amount.
2. You’re not going to be local aware (different locales have different formats for the same currency).

In general I don’t think the comparison you’re doing adds a lot of value - although of course I don’t know your use case and I may be missing something. If so, please let me know what you’re trying to achieve and I’ll help.

ex_cldr_number (that does the actually formatting for ex_money) has thousands of tests. If some formatting is incorrect then it’s a bug and I will fix it.

If the goal of the test isn’t the formatting of the msg string, but rather that the msg string contains the correct currency and amount, I’d consider using String.contains?/2 in the test instead.

assert String.contains?(msg, "AED")
assert String.contains?(msg, "1,234.00")