ReplaceSubstringWithSubstringBefore

Reports calls like s.substring(0, s.indexOf(x)) that can be replaced with s.substringBefore(x).

Using substringBefore() makes your code simpler.

The quick-fix replaces the substring call with substringBefore.

Example:

fun foo(s: String) {
      s.substring(0, s.indexOf('x'))
  }

After the quick-fix is applied:

fun foo(s: String) {
      s.substringBefore('x')
  }