Add tests around nullable attributes and remove unnecessary encoding code

Sources/JSONAPI/Resource/Attribute.swift

@@ -80,15 +80,6 @@ extension TransformedAttribute {
 	
 	public func encode(to encoder: Encoder) throws {
 		var container = encoder.singleValueContainer()
-		
-		// See note in decode above about the weirdness
-		// going on here.
-//		let anyNil: Any? = nil
-//		let nilRawValue = anyNil as? Transformer.From
-//		guard rawValue != nilRawValue else {
-//			try container.encodeNil()
-//			return
-//		}
 
 		try container.encode(rawValue)
 	}

Tests/JSONAPITests/Attribute/AttributeTests.swift

@@ -29,6 +29,29 @@ class AttributeTests: XCTestCase {
 	func test_TransformedAttributeReversNoThrow() {
 		XCTAssertNoThrow(try TransformedAttribute<String, TestTransformer>(transformedValue: 10))
 	}
+
+	func test_NullableIsNullIfNil() {
+		struct Wrapper: Codable {
+			let dummy: Attribute<String?>
+		}
+		let data = encoded(value: Wrapper(dummy: .init(value: nil)))
+		let string = String(data: data, encoding: .utf8)!
+
+		XCTAssertEqual(string, "{\"dummy\":null}")
+	}
+
+	func test_NullableIsEqualToNonNullableIfNotNil() {
+		struct Wrapper1: Codable {
+			let dummy: Attribute<String?>
+		}
+		struct Wrapper2: Codable {
+			let dummy: Attribute<String>
+		}
+		let data1 = encoded(value: Wrapper1(dummy: .init(value: "hello")))
+		let data2 = encoded(value: Wrapper2(dummy: .init(value: "hello")))
+
+		XCTAssertEqual(data1, data2)
+	}
 }
 
 // MARK: Test types

Tests/JSONAPITests/Entity/EntityTests.swift

@@ -207,6 +207,8 @@ extension EntityTests {
 		XCTAssertNil(entity[\.maybeHere])
 		XCTAssertNil(entity[\.maybeNull])
 		XCTAssertNoThrow(try TestEntity6.check(entity))
+
+		print(encodable: entity)
 	}
 
 	func test_entityOneNullAndOneOmittedAttribute_encode() {