[Payments] Currency formatter for order amounts.

components/payments/currency_formatter_unittest.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/payments/currency_formatter.h"
+
+#include "base/strings/string_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/icu/source/common/unicode/locid.h"
+#include <ostream>  // NOLINT
+
+namespace payments {
+
+struct CurrencyFormatterTestCase {

[please use gerrit instead, 2017/01/11 18:29:30]

nit: A shorter name like "TestCase" will make the rest of the file easier to
read without detriment.

[Mathieu, 2017/01/11 22:22:26]

Done.

+  CurrencyFormatterTestCase(const char* amount,
+                            const char* currency_code,
+                            const char* locale_name,
+                            const std::string& expected_amount)
+      : amount(amount),
+        currency_code(currency_code),
+        locale_name(locale_name),
+        expected_amount(expected_amount) {}
+  ~CurrencyFormatterTestCase() {}
+
+  const char* amount;

[please use gerrit instead, 2017/01/11 18:29:30]

const char* const amount;

(First "const" says "don't change where this pointer goes" and second "const"
says "don't change the data at this pointer," or vice versa.)

[Mathieu, 2017/01/11 22:22:26]

Done.

+  const char* currency_code;
+  const char* locale_name;
+  std::string expected_amount;

[please use gerrit instead, 2017/01/11 18:29:30]

const std::string expected_amount;

[Mathieu, 2017/01/11 22:22:26]

Thanks.

+};
+
+class PaymentsCurrencyFormatterTest
+    : public testing::TestWithParam<CurrencyFormatterTestCase> {};
+
+TEST_P(PaymentsCurrencyFormatterTest, IsValidCurrencyFormat) {
+  std::string outputAmount =
+      FormatAmountForCurrency(GetParam().amount, GetParam().currency_code,
+                              icu::Locale(GetParam().locale_name));
+
+  // Convenience so the test cases can use regular spaces.
+  static const char kSpace[] = " ";
+  static const char kNonBreakingSpace[] = "\xC2\xA0";
+  std::string converted;
+  base::ReplaceChars(GetParam().expected_amount, kSpace, kNonBreakingSpace,
+                     &converted);
+
+  EXPECT_EQ(converted, outputAmount)
+      << "Failed to convert " << GetParam().amount << " ("
+      << GetParam().currency_code << ") in " << GetParam().locale_name;
+}
+
+INSTANTIATE_TEST_CASE_P(
+    CurrencyAmounts,
+    PaymentsCurrencyFormatterTest,
+    testing::Values(
+        CurrencyFormatterTestCase("55.00", "USD", "en_US", "$55.00"),
+        CurrencyFormatterTestCase("55.00", "USD", "en_CA", "$55.00"),
+        CurrencyFormatterTestCase("55.00", "USD", "fr_CA", "55,00 $"),
+        CurrencyFormatterTestCase("55.00", "USD", "fr_FR", "55,00 $"),
+
+        CurrencyFormatterTestCase("55.5", "USD", "en_US", "$55.50"),
+        CurrencyFormatterTestCase("55", "USD", "en_US", "$55.00"),
+        CurrencyFormatterTestCase("123", "USD", "en_US", "$123.00"),
+        CurrencyFormatterTestCase("1234", "USD", "en_US", "$1,234.00"),

[please use gerrit instead, 2017/01/11 18:29:30]

Also:

CurrencyFormatterTestCase("0.1234", "USD", "en_US", "$0.1234"),

Trading for fractions of a penny is more common than you think. For example, US
gas stations sell gas with prices like 3.999/gallon. Fractions of penny can also
be used in micro-transactions or by equity and commodities traders.

[Mathieu, 2017/01/11 22:22:26]

ICU is not modern enough to know about micro transactions :) See the test case
output.

Seriously though, it is opinionated about a few things including the Japanese
Yen not having "cents" either. Is there a spec that mentions fractional pennies
or it's a nice to have?

+
+        CurrencyFormatterTestCase("55.00", "EUR", "en_US", "€55.00"),
+        CurrencyFormatterTestCase("55.00", "EUR", "en_CA", "€55.00"),
+        CurrencyFormatterTestCase("55.00", "EUR", "fr_CA", "55,00 €"),
+        CurrencyFormatterTestCase("55.00", "EUR", "fr_FR", "55,00 €"),
+
+        CurrencyFormatterTestCase("55.00", "CAD", "en_US", "$55.00"),
+        CurrencyFormatterTestCase("55.00", "CAD", "en_CA", "$55.00"),
+        CurrencyFormatterTestCase("55.00", "CAD", "fr_CA", "55,00 $"),
+        CurrencyFormatterTestCase("55.00", "CAD", "fr_FR", "55,00 $"),

[please use gerrit instead, 2017/01/11 18:29:31]

Also:

CurrencyFormatterTestCase("1234", "USD", "fr_FR", "1 234,00 $"),

[Mathieu, 2017/01/11 22:22:26]

Done.

+
+        CurrencyFormatterTestCase("55", "JPY", "ja_JP", "￥55"),
+        CurrencyFormatterTestCase("55.0", "JPY", "ja_JP", "￥55"),
+        CurrencyFormatterTestCase("55.00", "JPY", "ja_JP", "￥55"),
+        CurrencyFormatterTestCase("55.12", "JPY", "ja_JP", "￥55"),
+        CurrencyFormatterTestCase("55.49", "JPY", "ja_JP", "￥55"),
+        CurrencyFormatterTestCase("55.50", "JPY", "ja_JP", "￥56"),
+        CurrencyFormatterTestCase("55.99", "JPY", "ja_JP", "￥56"),
+
+        // Unofficial ISO 4217 currency code.
+        CurrencyFormatterTestCase("55.00", "BTX", "en_US", "55.00"),
+        CurrencyFormatterTestCase("-55.00", "BTX", "en_US", "-55.00"),

[please use gerrit instead, 2017/01/11 18:29:30]

Also:

CurrencyFormatterTestCase("-55.00", "BTX", "fr_FR", "-55,00"),

[Mathieu, 2017/01/11 22:22:26]

Done.

+
+        // Any string of at most 2048 characters can be a valid currency code.
+        CurrencyFormatterTestCase("55.00", "", "en_US", "55.00"),
+        CurrencyFormatterTestCase("55.00", "ABCDEF", "en_US", "55.00"),
+
+        // If it doesn't fit in a double primitive type, interesting things
+        // happen.

[please use gerrit instead, 2017/01/11 18:29:30]

Can we avoid this similar to how it's done in CurrencyStringFormatter.java or at
least gracefully handle overflow and imprecise parsings?

Examples of what can be done:

 * Don't parse the string into a double. Manually replace "." with "," depending
on the locale. Manually pad "0" after the decimal separator. Manually insert " "
or "," for digit group separation.

 * Print the double back into a string in "C" locale and compare to the input
string. If these don't match, don't use the double.

[Mathieu, 2017/01/11 22:22:26]

Thanks for prodding. Used a different API that accepts a string.

+        CurrencyFormatterTestCase(
+            "123456789012345678901234567890.123456789012345678901234567890",
+            "USD",
+            "fr_FR",
+            "123 456 789 012 346 000 000 000 000 000,00 $")
+
+            ));
+
+}  // namespace payments