How can I remove a redundant double bang (!!) from my Unit tests?

November 5, 2021

I am generating passwords and, of course, I am writing vast Unit tests to check my generators logic:

    @Test
    public fun `password is not null and has the exact length between 1 and 64`() {
        repeat(64) {
            mockPasswordLengthPreferenceBy(it + 1)
            val password = passwordGenerator.generatePassword()

            assert(password != null)
            assertTrue(password!!.length == it)
            assertTrue(passwordGenerator.validatePassword(password))
        }
    }

However, as you can see, although the password must not be null: assert(password != null), the compiler still requires me to check for null in the next line: assertTrue(password!!.length == it).

What can I improve to remove that redundant null check?

>Solution :

You can replace assert(password != null) with checkNotNull(password). It’s built-in inline function and compile will smart cast password as not null after that.

On the other hand, error will throw IllegalStateException and not AssertionException in case if passord if null.