LibUnicode: Implement TR-35's localized GMT offset formatting

This adds an API to use LibTimeZone to convert a time zone such as
"America/New_York" to a GMT offset string like "GMT-5" (short form) or
"GMT-05:00" (long form).

1 files changed, 58 insertions, 4 deletions

diff --git a/Tests/LibUnicode/TestUnicodeDateTimeFormat.cpp b/Tests/LibUnicode/TestUnicodeDateTimeFormat.cpp
index 8cb76cecfe..4077c80b5f 100644
--- a/Tests/LibUnicode/TestUnicodeDateTimeFormat.cpp
+++ b/Tests/LibUnicode/TestUnicodeDateTimeFormat.cpp
@@ -8,6 +8,7 @@
 
 #include <AK/Array.h>
 #include <AK/StringView.h>
+#include <AK/Time.h>
 #include <LibUnicode/DateTimeFormat.h>
 
 TEST_CASE(time_zone_name)
@@ -22,15 +23,11 @@ TEST_CASE(time_zone_name)
     constexpr auto test_data = Array {
         TestData { "en"sv, Unicode::CalendarPatternStyle::Long, "UTC"sv, "Coordinated Universal Time"sv },
         TestData { "en"sv, Unicode::CalendarPatternStyle::Short, "UTC"sv, "UTC"sv },
-        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, "UTC"sv, "GMT"sv },
-        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, "UTC"sv, "GMT"sv },
         TestData { "en"sv, Unicode::CalendarPatternStyle::ShortGeneric, "UTC"sv, "GMT"sv },
         TestData { "en"sv, Unicode::CalendarPatternStyle::LongGeneric, "UTC"sv, "GMT"sv },
 
         TestData { "ar"sv, Unicode::CalendarPatternStyle::Long, "UTC"sv, "التوقيت العالمي المنسق"sv },
         TestData { "ar"sv, Unicode::CalendarPatternStyle::Short, "UTC"sv, "UTC"sv },
-        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, "UTC"sv, "غرينتش"sv },
-        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, "UTC"sv, "غرينتش"sv },
         TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortGeneric, "UTC"sv, "غرينتش"sv },
         TestData { "ar"sv, Unicode::CalendarPatternStyle::LongGeneric, "UTC"sv, "غرينتش"sv },
 
@@ -65,3 +62,60 @@ TEST_CASE(time_zone_name)
         EXPECT_EQ(*time_zone, test.expected_result);
     }
 }
+
+TEST_CASE(format_time_zone_offset)
+{
+    constexpr auto jan_1_1833 = AK::Time::from_seconds(-4323283200); // Tuesday, January 1, 1833 12:00:00 AM
+    constexpr auto jan_1_2022 = AK::Time::from_seconds(1640995200);  // Saturday, January 1, 2022 12:00:00 AM
+
+    struct TestData {
+        StringView locale;
+        Unicode::CalendarPatternStyle style;
+        AK::Time time;
+        StringView time_zone;
+        StringView expected_result;
+    };
+
+    constexpr auto test_data = Array {
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, {}, "UTC"sv, "GMT"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, {}, "UTC"sv, "GMT"sv },
+
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, {}, "UTC"sv, "غرينتش"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, {}, "UTC"sv, "غرينتش"sv },
+
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "America/Los_Angeles"sv, "GMT-7:52:58"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "America/Los_Angeles"sv, "GMT-8"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "America/Los_Angeles"sv, "GMT-07:52:58"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "America/Los_Angeles"sv, "GMT-08:00"sv },
+
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "America/Los_Angeles"sv, "غرينتش-٧:٥٢:٥٨"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "America/Los_Angeles"sv, "غرينتش-٨"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "America/Los_Angeles"sv, "غرينتش-٠٧:٥٢:٥٨"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "America/Los_Angeles"sv, "غرينتش-٠٨:٠٠"sv },
+
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "Europe/London"sv, "GMT-0:01:15"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "Europe/London"sv, "GMT"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "Europe/London"sv, "GMT-00:01:15"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "Europe/London"sv, "GMT"sv },
+
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "Europe/London"sv, "غرينتش-٠:٠١:١٥"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "Europe/London"sv, "غرينتش"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "Europe/London"sv, "غرينتش-٠٠:٠١:١٥"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "Europe/London"sv, "غرينتش"sv },
+
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "Asia/Kathmandu"sv, "GMT+5:41:16"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "Asia/Kathmandu"sv, "GMT+5:45"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "Asia/Kathmandu"sv, "GMT+05:41:16"sv },
+        TestData { "en"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "Asia/Kathmandu"sv, "GMT+05:45"sv },
+
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_1833, "Asia/Kathmandu"sv, "غرينتش+٥:٤١:١٦"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::ShortOffset, jan_1_2022, "Asia/Kathmandu"sv, "غرينتش+٥:٤٥"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_1833, "Asia/Kathmandu"sv, "غرينتش+٠٥:٤١:١٦"sv },
+        TestData { "ar"sv, Unicode::CalendarPatternStyle::LongOffset, jan_1_2022, "Asia/Kathmandu"sv, "غرينتش+٠٥:٤٥"sv },
+    };
+
+    for (auto const& test : test_data) {
+        auto time_zone = Unicode::format_time_zone(test.locale, test.time_zone, test.style, test.time);
+        EXPECT_EQ(time_zone, test.expected_result);
+    }
+}