Fixes and tests for decoding binary items and empty lists in DynamoDBEvent.Decoder

Sources/AWSLambdaEvents/DynamoDB.swift

@@ -462,11 +462,14 @@ extension DynamoDBEvent {
         func decode(_ type: String.Type, forKey key: K) throws -> String {
             let value = try getValue(forKey: key)
 
-            guard case .string(let string) = value else {
+            switch value {
+            case .string(let string):
+                return string
+            case .binary(let binary):
+                return Data(binary).base64EncodedString()
+            default:
                 throw self.createTypeMismatchError(type: type, forKey: key, value: value)
             }
-
-            return string
         }
 
         func decode(_ type: Double.Type, forKey key: K) throws -> Double {
@@ -651,11 +654,14 @@ extension DynamoDBEvent {
         }
 
         func decode(_: String.Type) throws -> String {
-            guard case .string(let string) = self.value else {
+            switch self.value {
+            case .string(let string):
+                return string
+            case .binary(let binary):
+                return Data(binary).base64EncodedString()
+            default:
                 throw self.createTypeMismatchError(type: String.self, value: self.value)
             }
-
-            return string
         }
 
         func decode(_: Double.Type) throws -> Double {
@@ -769,6 +775,9 @@ extension DynamoDBEvent {
             self.codingPath = codingPath
             self.array = array
             self.count = array.count
+
+            // No need to decode if array is empty
+            self.isAtEnd = array.isEmpty
         }
 
         mutating func decodeNil() throws -> Bool {

Tests/AWSLambdaEventsTests/DynamoDBTests.swift

@@ -251,4 +251,59 @@ struct DynamoDBTests {
         #expect(test?.foo == "bar")
         #expect(test?.xyz == 123)
     }
+
+    @Test func decoderEmptyList() {
+        let value: [String: DynamoDBEvent.AttributeValue] = [
+            "fooList": .list([])
+        ]
+
+        struct Test: Codable {
+            let fooList: [Int]
+        }
+
+        let test = try? DynamoDBEvent.Decoder().decode(Test.self, from: value)
+        #expect(test?.fooList == [])
+    }
+
+    @Test func decoderNonEmptyList() {
+        let value: [String: DynamoDBEvent.AttributeValue] = [
+            "fooList": .list([.string("test")])
+        ]
+
+        struct Test: Codable {
+            let fooList: [String]
+        }
+
+        let test = try? DynamoDBEvent.Decoder().decode(Test.self, from: value)
+        #expect(test?.fooList == ["test"])
+    }
+
+    @Test func decoderBinaryToBase64KeyedDecodingContainer() {
+        let value: [String: DynamoDBEvent.AttributeValue] = [
+            "xyz": .binary([0x74, 0x65, 0x73, 0x74])  // UTF8 for "test"
+        ]
+
+        struct Test: Codable {
+            let xyz: String
+        }
+
+        let test = try? DynamoDBEvent.Decoder().decode(Test.self, from: value)
+        #expect(test?.xyz == "dGVzdA==")  // base64 for "test"
+    }
+
+    @Test func decoderBinaryToBase64SingleValueDecodingContainer() {
+        let value: DynamoDBEvent.AttributeValue = .binary([0x74, 0x65, 0x73, 0x74])  // UTF8 for "test"
+
+        let test = try? DynamoDBEvent.Decoder().decode(String.self, from: value)
+        #expect(test == "dGVzdA==")  // base64 for "test"
+    }
+
+    @Test func decoderBinaryToBase64UnkeyedDecodingContainer() {
+        let value: DynamoDBEvent.AttributeValue = .list([
+            .binary([0x74, 0x65, 0x73, 0x74])  // UTF8 for "test"
+        ])
+
+        let test = try? DynamoDBEvent.Decoder().decode([String].self, from: value)
+        #expect(test == ["dGVzdA=="])  // base64 for "test"
+    }
 }