Having problem comparing Money struct string output

Questions / Help
1

Despite copy and pasting the output, the comparison still return false

iex(2)> Money.to_string! Money.new(:AED, 1234)
"AED 1,234.00"
iex(3)> (Money.to_string! Money.new(:AED, 1234)) == "AED 1,234.00"
false

With more inspection, i can see they are different

ex(5)> (Money.to_string! Money.new(:AED, 1234)) |> IO.inspect(base: :hex)          
<<0x41, 0x45, 0x44, 0xC2, 0xA0, 0x31, 0x2C, 0x32, 0x33, 0x34, 0x2E, 0x30, 0x30>>
"AED 1,234.00"
iex(6)> "AED 1,234.00" |> IO.inspect(base: :hex)                          
<<0x41, 0x45, 0x44, 0x20, 0x31, 0x2C, 0x32, 0x33, 0x34, 0x2E, 0x30, 0x30>>
"AED 1,234.00"

Problem is how can i get Money.to_string output to output “regular” space characters so that comparison passes?
I looked into Cldr.Number — Cldr Numbers v2.31.0 but don’t see anything useful.

2

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.

7 Likes
3

Just mainly using this comparison in tests. For example

assert msg = "Final Price: AED 1,234.00"
4

Ok, I thought that was probably it. I think the best way to do that is to capture the output in iex and then, if you consider it to be correct, to copy/paste the emitted value into your tests. That’s exactly how I build most of the tests ex_cldr_numbers and ex_money.

5

I actually did what you suggested before this. It seems like copy and pasting still pasted the output as regular space character. But no worries i can type it out now

6

That’s interesting! Maybe some editors convert non-breaking to breaking space when pasting? I’ll do some searching on that so I can document it for the next person. Please update the thread if you find the cause?

7

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")
2 Likes
8

It must be an iex console limitation! In a regular editor you would’ve seen a visual warning (VSCode here):

Code_aru9ALj2DT

But that would need to be a test output to capture such a nuance.