[Config] Add encoder and decoder param to public codable APIs (#14525)

Author: ncooke3

FirebaseRemoteConfig/CHANGELOG.md

@@ -1,3 +1,8 @@
+# Unreleased
+- [fixed] Codable APIs now accept optional `FirebaseDataEncoder` and
+  `FirebaseDataDecoder` parameters, allowing for customization of
+  encoding/decoding behavior. (#14368)
+
 # 11.9.0
 - [fixed] Mark internal `fetchSession` property as `atomic` to prevent a concurrency
   related crash. (#14449)

FirebaseRemoteConfig/Swift/Codable.swift

@@ -47,19 +47,21 @@ public extension RemoteConfig {
   /// Decodes a struct from the respective Remote Config values.
   ///
   /// - Parameter asType: The type to decode to.
-  func decoded<Value: Decodable>(asType: Value.Type = Value.self) throws -> Value {
+  func decoded<Value: Decodable>(asType: Value.Type = Value.self,
+                                 decoder: FirebaseDataDecoder = .init()) throws -> Value {
     let keys = allKeys(from: RemoteConfigSource.default) + allKeys(from: RemoteConfigSource.remote)
     let config = keys.reduce(into: [String: FirebaseRemoteConfigValueDecoderHelper]()) {
       $0[$1] = FirebaseRemoteConfigValueDecoderHelper(value: configValue(forKey: $1))
     }
-    return try FirebaseDataDecoder().decode(Value.self, from: config)
+    return try decoder.decode(Value.self, from: config)
   }
 
   /// Sets config defaults from an encodable struct.
   ///
   /// - Parameter value: The object to use to set the defaults.
-  func setDefaults<Value: Encodable>(from value: Value) throws {
-    guard let encoded = try FirebaseDataEncoder().encode(value) as? [String: NSObject] else {
+  func setDefaults<Value: Encodable>(from value: Value,
+                                     encoder: FirebaseDataEncoder = .init()) throws {
+    guard let encoded = try encoder.encode(value) as? [String: NSObject] else {
       throw RemoteConfigCodableError.invalidSetDefaultsInput(
         "The setDefaults input: \(value), must be a Struct that encodes to a Dictionary"
       )

FirebaseRemoteConfig/Tests/Swift/SwiftAPI/Codable.swift

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 import FirebaseRemoteConfig
+import FirebaseSharedSwift
 
 import XCTest
 
@@ -206,4 +207,35 @@ class CodableTests: APITestBase {
     XCTAssertEqual(readDefaults.arrayValue, ["foo", "bar", "baz"])
     XCTAssertEqual(readDefaults.arrayIntValue, [1, 2, 0, 3])
   }
+
+  // MARK: - Test using injected encoder/decoder.
+
+  func testDateEncodingAndDecodingWithNonDefaultCoders() throws {
+    // Given
+    struct DateDefaults: Codable {
+      let date: Date
+    }
+
+    let defaults = DateDefaults(date: Date())
+
+    // When
+    let encoder = FirebaseDataEncoder()
+    encoder.dateEncodingStrategy = .iso8601
+    try config.setDefaults(from: defaults, encoder: encoder)
+
+    // - Uses default decoder that won't decode ISO8601 format.
+    let improperlyDecodedDefaults: DateDefaults = try config.decoded()
+    XCTAssertNotEqual(improperlyDecodedDefaults.date, defaults.date)
+
+    // Then
+    let decoder = FirebaseDataDecoder()
+    decoder.dateDecodingStrategy = .iso8601
+
+    let decodedDefaults: DateDefaults = try config.decoded(decoder: decoder)
+    XCTAssert(Calendar.current.isDate(
+      decodedDefaults.date,
+      equalTo: defaults.date,
+      toGranularity: .second
+    ))
+  }
 }