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

Issue

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).

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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.

Answered By - S-Sh