refactor: match upstream grouping in FormatNumberForMobileDialing

csharp/PhoneNumbers.Test/TestPhoneNumberUtil.cs

@@ -951,6 +951,26 @@ public void TestFormatNumberForMobileDialing()
             Assert.Equal("+800 1234 5678",
                 phoneUtil.FormatNumberForMobileDialing(InternationalTollFree, RegionCode.JP, true));
 
+            // Dialling a non-geographical number from the non-geographical pseudo-region takes the
+            // "calling from the number's own region" path, which the cases above skip because JP is
+            // not 001. International format either way, since non-geographical numbers are always
+            // internationally diallable.
+            Assert.Equal("+80012345678",
+                phoneUtil.FormatNumberForMobileDialing(InternationalTollFree, RegionCode.UN001, false));
+            Assert.Equal("+800 1234 5678",
+                phoneUtil.FormatNumberForMobileDialing(InternationalTollFree, RegionCode.UN001, true));
+
+            // MX fixed line and mobile numbers dialled from MX: international format, because a
+            // national-format call needs a carrier code that depends on both parties' local area.
+            // This is the MX/CL/UZ arm of the same branch, which short-circuit evaluation reaches
+            // only when the number's region is not the non-geographical one.
+            Assert.Equal("+52 1 234 567 8900",
+                phoneUtil.FormatNumberForMobileDialing(MXMobile1, RegionCode.MX, true));
+            Assert.Equal("+5212345678900",
+                phoneUtil.FormatNumberForMobileDialing(MXMobile1, RegionCode.MX, false));
+            Assert.Equal("+52 33 1234 5678",
+                phoneUtil.FormatNumberForMobileDialing(MXNumber1, RegionCode.MX, true));
+
             // Test that the Australian emergency number 000 is formatted correctly.
             var auNumber = new PhoneNumber.Builder()
                 .SetCountryCode(61)

csharp/PhoneNumbers/PhoneNumberUtil.cs

@@ -1333,23 +1333,23 @@
                     // For non-geographical countries, and Mexican, Chilean, and Uzbek fixed line and mobile
                     // numbers, we output international format for numbers that can be dialed internationally as
                     // that always works.
-                    if (regionCode == REGION_CODE_FOR_NON_GEO_ENTITY
+                    if ((regionCode == REGION_CODE_FOR_NON_GEO_ENTITY
                         // MX fixed line and mobile numbers should always be formatted in international format,
                         // even when dialed within MX. For national format to work, a carrier code needs to be
                         // used, and the correct carrier code depends on if the caller and callee are from the
                         // same local area. It is trickier to get that to work correctly than using
                         // international format, which is tested to work fine on all carriers.
                         // CL fixed line numbers need the national prefix when dialing in the national format,
                         // but don't have it when used for display. The reverse is true for mobile numbers.  As
                         // a result, we output them in the international format to make it work.
                         // UZ mobile and fixed-line numbers have to be formatted in international format or
                         // prefixed with special codes like 03, 04 (for fixed-line) and 05 (for mobile) for
                         // dialling successfully from mobile devices. As we do not have complete information on
                         // special codes and to be consistent with formatting across all phone types we return
                         // the number in international format here.
                         || ((regionCode == "MX" || regionCode == "CL"
-                                || regionCode == "UZ") && isFixedLineOrMobile)
+                                || regionCode == "UZ") && isFixedLineOrMobile))
                         && CanBeInternationallyDialled(numberNoExt))
                     {
                         formattedNumber = Format(numberNoExt, PhoneNumberFormat.INTERNATIONAL);
                     }