JSONValueTests.swift

import XCTest

fileprivate extension JSONValue {
  var objectValue: [String: JSONValue]? {
    switch self {
    case .object(let value): return value
    default: return nil
    }
  }
  var arrayValue: [JSONValue]? {
    switch self {
    case .array(let value): return value
    default: return nil
    }
  }
}

private let testData = """
{
  "data": {
    "intValue": 100,
    "intValueNegative": -100,
    "intValueAsFloat": 120.0,
    "doubleValue": 150.5,
    "stringValue": "1.9",
    "boolValue": true,
    "arrayValue": ["array1", "array2"],
    "dictValue": {"value1": true, "value2": "golf"}
  }
}
"""

class JSONValueTests: XCTestCase {

  var sut: Data!

  override func setUp() {
    super.setUp()
    sut = testData.data(using: .utf8)
  }

  func testJSONValueDecoding() {
    let value = try? JSONDecoder().decode(JSONValue.self, from: sut)
    XCTAssertTrue(value != nil)
  }

  func testJSONValueTypes() {
    let root = try! JSONDecoder().decode(JSONValue.self, from: sut)
    let data = root.objectValue!["data"]
    switch data {
    case .object(let value):
      XCTAssertEqual(value["intValue"]!.value as! Double, 100.0)
      XCTAssertEqual(value["intValueNegative"]!.value as! Double, -100.0)
      XCTAssertEqual(value["intValueAsFloat"]!.value as! Double, 120.0)
      XCTAssertEqual(value["doubleValue"]!.value as! Double, 150.5)
      XCTAssertEqual(value["stringValue"]!.value as! String, "1.9")
      XCTAssertEqual(value["boolValue"]!.value as! Bool, true)
      XCTAssertEqual(value["arrayValue"]!.arrayValue![0].value as! String, "array1")
      XCTAssertEqual(value["dictValue"]!.objectValue!["value2"]!.value as! String, "golf")
    default:
      XCTFail("Expected to parse a `object` but got \(data!)")
    }
  }

  func test_BooleanEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.boolean(true))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), "true")
  }

  func test_StringEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.string("test"))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), #""test""#)
  }

  func test_IntEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.number(1))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), "1")
  }

  func test_DoubleEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.number(1.2))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), "1.2")
  }

  func test_IntAsDoubleEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.number(1.0))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), "1")
  }

  func test_DoubleEncodingWithRoundingError() {
    let encoded = try! JSONEncoder().encode(JSONValue.number(1.9))
    XCTAssertEqual(String(data: encoded, encoding: .utf8)!.prefix(4), "1.89")
  }

  func test_ObjectEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.object(["test": .string("data")]))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), #"{"test":"data"}"#)
  }

  func test_ArrayEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.array([.string("test"), .string("test")]))
    XCTAssertEqual(String(data: encoded, encoding: .utf8), #"["test","test"]"#)
  }

  func test_NullEncoding() {
    let encoded = try! JSONEncoder().encode(JSONValue.null)
    XCTAssertEqual(String(data: encoded, encoding: .utf8), "null")
  }

}