add millisecond precision

Author: sebsto

Sources/AWSLambdaRuntime/Logging/JSONLogHandler.swift

@@ -16,7 +16,7 @@
 import Logging
 
 #if canImport(Darwin)
-import Darwin.C
+import Darwin
 #elseif canImport(Glibc)
 import Glibc
 #elseif canImport(Musl)
@@ -169,7 +169,10 @@ public struct JSONLogHandler: LogHandler {
     /// Returns nil if encoding fails.
     internal static func encodeLogEntry(_ logEntry: LogEntry) -> Data? {
         let encoder = JSONEncoder()
-        encoder.dateEncodingStrategy = .iso8601
+        encoder.dateEncodingStrategy = .custom { date, encoder in
+            var container = encoder.singleValueContainer()
+            try container.encode(date.formatted(Date.ISO8601FormatStyle(includingFractionalSeconds: true)))
+        }
         encoder.outputFormatting = []  // Compact output (no pretty printing)
         return try? encoder.encode(logEntry)
     }

Tests/AWSLambdaRuntimeTests/JSONLogHandlerTests.swift

@@ -183,10 +183,10 @@ struct JSONLogHandlerTests {
         let timestamp = entry?.timestamp
         #expect(timestamp != nil)
 
-        // Verify it matches ISO 8601 format (e.g. "2024-01-16T10:30:45Z")
-        let iso8601Pattern = #"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\\d+)?Z$"#
+        // Verify it matches ISO 8601 format with milliseconds (e.g. "2024-01-16T10:30:45.123Z")
+        let iso8601Pattern = #"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{1,6}Z$"#
         let matches = timestamp?.range(of: iso8601Pattern, options: .regularExpression) != nil
-        #expect(matches, "Timestamp '\(timestamp ?? "")' should be in ISO 8601 format")
+        #expect(matches, "Timestamp '\(timestamp ?? "")' should be in ISO 8601 format with fractional seconds")
     }
 
     // MARK: - Metadata subscript