Fix amount text field breaking when decimal separator has spaces

[staskus]

Closes: #14045

Description

The amount of text field breaks when the decimal separator has spaces. It breaks a few text fields - including adding custom amounts and coupons.

PriceFieldFormatter and PriceInputFormatter don't take into consideration that the decimal separator has spaces.

Solution

As I tested, even the native number formatter ignores spaces in the decimal separator when converting numbers back to decimal. I think the best option is to ignore spaces in separators when formatting the amount in the text field. It helps avoid issues between number conversions. In labels, we can continue displaying spaces.

The solution is to use decimal and thousands separators without spaces in PriceFieldFormatter and PriceInputFormatter. I also explored a possibility of removing one of these formatters but they have quite a different behavior around the edges so I left it outside the scope.

Steps to reproduce

Coupons

1. Edit store settings (WooCommerce -> Settings) to have decimal separator with spaces (". ")
2. Go to Menu
3. Coupons
4. Add coupon
5. Fixed cart discount
6. try to add a price that has a decimal point
7. Confirm the value is added as expected

Custom Amount

1. Edit store settings (WooCommerce -> Settings) to have decimal separator with spaces (". ")
2. Menu
3. Payments
4. Collect Payment
5. Enter custom amount with decimal values
6. Confirm the value is added as expected

Testing information

• Added unit tests for these cases.
• Additionally tested other price fields (Product Creation, Discounts)
• Tested spaces in thousands separator since this is a more common case

Screenshots

Custom Amount - Decimals

Custom.Amount.-.Decimals.mp4

Coupon - Decimals

Coupon.-.Decimals.mp4

Coupon - Decimal and Thousands

Coupon.-.Decimal.and.Thousands.mp4

---

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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📲 You can test the changes from this Pull Request in WooCommerce iOS by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS
	Build Number	pr14057-7ca9a81
	Version	20.5
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	7ca9a81
	App Center Build	WooCommerce - Prototype Builds #11036

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[iamgabrielma]

Works nicely, thanks for addressing this! I found some oddities when testing, but nothing with priority or in the scope of this PR, I've reported them separately:

• Coupons price input doesn't account for limit of decimals in store settings #14071
• Custom Amounts UI placeholder shows additional spaces if these were added to store settings #14072

I'll go ahead and merge the changes. Left a few comments, but feel free to address them when you're back from AFK 🙇

[iamgabrielma]

Suggested change

	var sanitizedGroupingSeparator: String {
	return groupingSeparator.replacingOccurrences(of: " ", with: "")
	}

This one is currently not used anywhere, so perhaps we want to remove it? If we don't, maybe we should rename it from sanitizedGroupingSeparator to sanitizedThousandSeparator?

The CodingKey in the CurrencySettings doesn't seem to follow the decoding pattern for this value: If we check the Networking.SystemStatus+Settings it's initially decoded as case thousandSeparator = "thousand_separator", but at some point we started to name it "groupingSeparator" in CurrencySettings (perhaps because of the native NumberFormatter?) so perhaps makes sense to refactor the name here and there for consistency, wdyt?

[iamgabrielma]

💯

[iamgabrielma]

We're not testing for space sanitization here, are we? If the input simulates what the merchant introduces in the textfield, and then this input is sanitized within formatter.format(value), shouldn't we pass the value in as malformed to the formatter? (The test still succeeds)

Suggested change

	// When
	let input = "189.20"
	// Then formatting ignores spaces in store decimal separator settings
	XCTAssertEqual(formatter.format(input: input), "189.20")
	// When
	let input = "189. 20"
	// Then formatting ignores spaces in store decimal separator settings
	XCTAssertEqual(formatter.format(input: input), "189.20")

[staskus]

@iamgabrielma thanks for taking care of this - reviewing, creating additional tasks, and merging!