Document Argument Captors in README

[TTransmit]

It would be nice to have an example of the syntax for using Argument Captors in Mockito-Kotlin. I got caught out because I used argumentCaptor.capture() instead of capture(argumentCaptor).

Here is an example of what it could be.

Argument Captors

These overcome the issue that Mockito ArgumentCaptor.capture() returns null, which results in an IllegalStateException in Kotlin.

Kotlin:

val argumentCaptor = argumentCaptor<String>()
myClass.doSomething()
verify(classToMock).sendString(capture(argumentCaptor))

I can raise this as a pull request if helpful. I would suggest adding it below the Argument Matchers section.

[nhaarman]

The more idiomatic way is even:

myClass.doSomething()
verify(classToMock).sendString(capture { s ->
    assertEquals("test", s)
})

I will add an example to the readme.