Refactor RetryModifierTests for improved clarity and functionality

- Updated retry tests to use async/await syntax for better readability.
- Enhanced retry limit tests to cover default and nil conditions.
- Added tests for exponential backoff and dynamic retry intervals.
- Improved retry condition tests to include safe method checks and status code conditions.
- Refactored test methods to ensure consistent naming and structure.
- Updated TestHTTPClient to support async testing, ensuring compatibility with new async test methods.

Author: dankinsoid

README.md

@@ -161,7 +161,7 @@ Custom callers can be created for different types of requests, such as WebSocket
 The `.decodable` serializer uses the `.bodyDecoder` configuration, which can be customized with the `.bodyDecoder` modifier. The default `bodyDecoder` is `JSONDecoder()`.
 
 #### Some execution modifiers
-- `.retry(limit:)` for retrying a request a specified number of times.
+- `.retry()` for retrying requests with configurable conditions, limits, intervals, and automatic `Retry-After` header support.
 - `.throttle(interval:)` for throttling requests with a specified interval.
 - `.timeout(_:)` for setting an execution timeout.
 - `.waitForConnection()` for waiting for a connection before executing a request.

Sources/SwiftAPIClient/APIClientConfigs.swift

@@ -18,16 +18,19 @@ public extension APIClient {
 		/// - Parameter keyPath: A `WritableKeyPath` to the configuration property.
 		/// - Returns: The value of the configuration property if it exists, or `nil` otherwise.
 		public subscript<T>(_ keyPath: WritableKeyPath<APIClient.Configs, T>) -> T? {
-			get { values[keyPath] as? T }
-			set { values[keyPath] = newValue }
-		}
-
-		/// Provides subscript access to configuration values based on their key paths.
-		/// - Parameter keyPath: A `WritableKeyPath` to the configuration property.
-		/// - Returns: The value of the configuration property if it exists, or `nil` otherwise.
-		public subscript<T>(_ keyPath: WritableKeyPath<APIClient.Configs, T?>) -> T? {
-			get { values[keyPath] as? T }
-			set { values[keyPath] = newValue }
+			get {
+				if let value = values[keyPath] {
+					return value as? T
+				}
+				return nil
+			}
+			set {
+				if let newValue {
+					values[keyPath] = newValue
+				} else {
+					values.removeValue(forKey: keyPath)
+				}
+			}
 		}
 
 		/// Returns a new `Configs` instance with a modified configuration value.

Sources/SwiftAPIClient/Modifiers/CodeLocation.swift

@@ -25,7 +25,7 @@ public extension APIClient.Configs {
 
 	/// The code location of the call site.
 	var codeLocation: CodeLocation? {
-		get { self[\.codeLocation] }
+		get { self[\.codeLocation] ?? nil }
 		set { self[\.codeLocation] = newValue }
 	}
 }