Hi everybody, I have a stupid question about the kotlin test. How to assert a nullable object nonNu...

# test

[hantsy]

Hi everybody, I have a stupid question about the kotlin test. How to assert a nullable object nonNull and make it type safe.

I have tried to use kotlin-test assertNotNull to assert an object non null, but finally in the following codes, I still have to use !! to convert it to non null value, if possible use some assert to convert it non null safely?

class MyTest{

  var result: XXX? = null

  fun test() {
    //...
    // saving data into db and got the result
    assertNotNull(result)

    result.someProperty // if possible use this directly, with type cast to none null using !! 
  }
}

[agrosner]

Use a val

[agrosner]

Or assign it one

[xoangon]

This happens because between the call to assertNotNull(result) and result.someProperty, the value of result could be modified from another thread.

You can use an scope function like let, that will guarantee that the value hasn't been mutated in that scope:

class MyTest{

  var result: XXX? = null

  fun test() {
    //...
    // saving data into db and got the result
    result?.let { result ->
      result.someProperty
    }
  }
}