testing builder code example

Example: testing builder

// The builder
class LoggerBuilder {
  var sink: LogSink = MockLogSink()
  var config: LogConfig = TestLogConfig()

  func build() -> Logger {
    return Logger(sink: sink, config: config)
  }
}

// in a test class
func testLoggerWritesToSuppliedSink() {
  let loggerBuilder = LoggerBuilder()
  let logger = loggerBuilder.build()
  logger.log("hello world")
  XCTAssertTrue(loggerBuilder.sink.contains("hello world")
}