Scala tests with Either and Pattern Matching best practice

I want to test my method which returns an Either. This is how i do this:

@Test def `Test empty name is not valid`: Unit = {
    val book = createBook()
    val result = insertEntryToBook(book, "", "12345")

    result match {
      case Left(InvalidNameFormat) => true
      case _ => fail()
    }
  }

Should i do some assert() call instead of fail() to make the test's fail message more explicit (e.g. for assertion side-to-side view)?