Fixed decoding nil

Author: colemancda

Sources/Decoder.swift

@@ -471,12 +471,9 @@ internal struct TLVKeyedDecodingContainer <K: CodingKey> : KeyedDecodingContaine
 
         self.decoder.log?("Check if nil at path \"\(decoder.codingPath.path)\"")
 
-        // check if key exists
-        guard let item = try self.value(for: key) else {
-            throw DecodingError.keyNotFound(key, DecodingError.Context(codingPath: self.decoder.codingPath, debugDescription: "No value associated with key \(key.stringValue)."))
-        }
-        
-        return item.value.isEmpty
+        // check if key exists since there is no way to represent nil in TLV
+        // empty data and strings should not be falsely reported as nil
+        return try self.value(for: key) == nil
     }
 
     func decode(_ type: Bool.Type, forKey key: Key) throws -> Bool {

Tests/TLVCodingTests/TLVCodingTests.swift

@@ -18,8 +18,7 @@ final class TLVCodingTests: XCTestCase {
         ("testUUID", testUUID),
         ("testDate", testDate),
         ("testDateSecondsSince1970", testDateSecondsSince1970),
-        ("testOutputFormatting", testOutputFormatting),
-        ("testNil", testNil)
+        ("testOutputFormatting", testOutputFormatting)
     ]
 
     func testCodable() {
@@ -85,6 +84,26 @@ final class TLVCodingTests: XCTestCase {
             Data([])
         )
 
+        compare(
+            CustomEncodable(
+                data: Data(),
+                uuid: nil,
+                number: nil,
+                date: nil
+            ),
+            Data([0, 0])
+        )
+        
+        compare(
+            CustomEncodable(
+                data: Data([0x00, 0x01]),
+                uuid: nil,
+                number: nil,
+                date: nil
+            ),
+            Data([0, 2, 0x00, 0x01])
+        )
+        
         compare(
             Profile(
                 person: Person(
@@ -352,31 +371,6 @@ final class TLVCodingTests: XCTestCase {
 
         XCTAssertNotEqual(try encoder.encode(value), try encoder.encode(valueUnordered))
     }
-    
-    func testNil() {
-        
-        let data = Data([
-            0,0,
-            3,0
-        ])
-        
-        let value = CustomEncodable(
-            data: nil,
-            uuid: nil,
-            number: nil,
-            date: nil
-        )
-        
-        var decoder = TLVDecoder()
-        decoder.log = { print("Decoder:", $0) }
-        do {
-            let decodedValue = try decoder.decode(type(of: value), from: data)
-            XCTAssertEqual(decodedValue, value)
-        } catch {
-            dump(error)
-            XCTFail("Could not decode \(value)")
-        }
-    }
 }
 
 private extension TLVCodingTests {