get id and type tests into the encoded entity test function

Tests/JSONAPITests/Test Helpers/EncodedAttributeTest.swift

@@ -19,7 +19,7 @@ private struct Wrapper<Value: Equatable & Codable, Transform: Transformer>: Coda
 }
 
 /// This function attempts to just cast to the type, so it only works
-/// for Attributes of primitive types.
+/// for Attributes of primitive types (primitive to JSON).
 func testEncodedPrimitive<Value: Equatable & Codable, Transform: Transformer>(attribute: TransformedAttribute<Value, Transform>) {
 	let encodedAttributeData = encoded(value: Wrapper<Value, Transform>(x: attribute))
 	let wrapperObject = try! JSONSerialization.jsonObject(with: encodedAttributeData, options: []) as! [String: Any]

Tests/JSONAPITests/Test Helpers/EncodedEntityPropertyTest.swift

@@ -17,6 +17,18 @@ func testEncoded<E: EntityType>(entity: E) {
 
 	XCTAssertNotNil(jsonDict)
 
+	let jsonId = jsonDict?["id"]
+
+	if E.EntityRawIdType.self == Unidentified.self {
+		XCTAssertNil(jsonId)
+	} else {
+		XCTAssertNotNil(jsonId)
+	}
+
+	let jsonType = jsonDict?["type"] as? String
+
+	XCTAssertEqual(jsonType, E.type)
+
 	let jsonAttributes = jsonDict?["attributes"] as? [String: Any]
 
 	if E.Attributes.self == NoAttributes.self {