Fix test failures

Author: jmschonfeld

Tests/FoundationInternationalizationTests/CalendarTests.swift

@@ -202,21 +202,21 @@ private struct CalendarTests {
         #expect(anyHashables[1] == anyHashables[2])
     }
 
-    func decodeHelper(_ l: Calendar) -> Calendar {
+    func decodeHelper(_ l: Calendar) throws -> Calendar {
         let je = JSONEncoder()
-        let data = try! je.encode(l)
+        let data = try je.encode(l)
         let jd = JSONDecoder()
-        return try! jd.decode(Calendar.self, from: data)
+        return try jd.decode(Calendar.self, from: data)
     }
 
-    @Test func serializationOfCurrent() async {
-        await usingCurrentInternationalizationPreferences {
+    @Test func serializationOfCurrent() async throws {
+        try await usingCurrentInternationalizationPreferences {
             let current = Calendar.current
-            let decodedCurrent = decodeHelper(current)
+            let decodedCurrent = try decodeHelper(current)
             #expect(decodedCurrent == current)
 
             let autoupdatingCurrent = Calendar.autoupdatingCurrent
-            let decodedAutoupdatingCurrent = decodeHelper(autoupdatingCurrent)
+            let decodedAutoupdatingCurrent = try decodeHelper(autoupdatingCurrent)
             #expect(decodedAutoupdatingCurrent == autoupdatingCurrent)
 
             #expect(decodedCurrent != decodedAutoupdatingCurrent)
@@ -227,7 +227,7 @@ private struct CalendarTests {
             // Calendar, unlike TimeZone and Locale, has some mutable properties
             var modified = Calendar.autoupdatingCurrent
             modified.firstWeekday = 6
-            let decodedModified = decodeHelper(modified)
+            let decodedModified = try decodeHelper(modified)
             #expect(decodedModified != autoupdatingCurrent)
             #expect(modified == decodedModified)
         }

Tests/FoundationInternationalizationTests/CurrentInternationalizationPreferencesActor.swift

@@ -25,17 +25,25 @@ private actor CurrentInternationalizationPreferencesActor: GlobalActor {
 
     private init() {}
 
+    private static func resetCaches() {
+        LocaleCache.cache.reset()
+        CalendarCache.cache.reset()
+        _ = TimeZoneCache.cache.reset()
+        _ = TimeZone.resetSystemTimeZone()
+        TimeZoneCache.cache.setDefault(nil)
+    }
+    
     @CurrentInternationalizationPreferencesActor
     static func usingCurrentInternationalizationPreferences(
         body: () throws -> Void // Must be synchronous to prevent suspension points within body which could introduce a change in the preferences
     ) rethrows {
+        // Reset caches before the test to clean up any lingering, eagerly realized values
+        resetCaches()
+        
         try body()
 
         // Reset everything after the test runs to ensure custom values don't persist
-        LocaleCache.cache.reset()
-        CalendarCache.cache.reset()
-        _ = TimeZoneCache.cache.reset()
-        _ = TimeZone.resetSystemTimeZone()
+        resetCaches()
     }
 }
 

Tests/FoundationInternationalizationTests/Formatting/DateFormatStyleTests.swift

@@ -100,7 +100,9 @@ private struct DateFormatStyleTests {
     }
 
     @Test func codable() throws {
-        let style = Date.FormatStyle(date: .long, time: .complete, locale: Locale(identifier: "en_US"), calendar: Calendar(identifier: .gregorian), timeZone: .gmt, capitalizationContext: .unknown)
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.timeZone = .gmt
+        let style = Date.FormatStyle(date: .long, time: .complete, locale: Locale(identifier: "en_US"), calendar: calendar, timeZone: .gmt, capitalizationContext: .unknown)
             .era()
             .year()
             .quarter()