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kotlinlang

Hey everyone, I’m using (well I’m trying to use :slightly_smiling_face: ) `bindingCatch` to compose a sequence of actions (API call, db call etc). What’s the best way to test it and to assure the actions are executed?

Hi <@U3GLDBG20> what is the return type of your actions? there may be better alternatives than bindingCatch if they are effects

<@U4UGS5FC7> return type is Either&lt;A, B&gt; and actually we already changed it to a binding&lt;A, B&gt; { … }

the test is ok up until the point where I’m trying to mock the `.bind()` part without success though

Can you provide a small example, maybe we can help ? :slightly_smiling_face:

We have something like this:
```
//UseCase.kt
fun sync() {
  binding&lt;Error, List&lt;T&gt;&gt; {
    //myList() returns Either&lt;Error, List&lt;A&gt;&gt;
    val myList = myRepo.getList().bind()
    val localIds = myList.map { it.id }
    // getCustomersByIds() returns Either&lt;Error, List&lt;T&gt;&gt;
    val customersE = myRepo.getCustomersByIds(localIds)
    customersE
   }.fix()
}
```

```
@ Test
fun `test binding`() {
   runBlocking { //because of coroutines and stuff
      whenever(myRepo).getList().thenReturn(aList)
      //here the test fails
   }
} 
```

when debugging the test, we noticed that the call to `bind()` is what actually falis the test

is it an option to change the return types in terms of IO?

My recomendation is to go down the IO path because in the 0.11.0 we will have BIO with support for custom errors and fx binding along with concurrency etc

which will give you more powerful and elegant programs

Thanks for the feedback. I’ve been reading the docs on Fx but unfortunately right now switching to IO and 0.9,1 would be too complex. we will do that in the future for sure. do you have anyway an idea on how to mock the bind() call in tests?

You can provide your own MonadContinuation or Monad instance that overrides bind, but would be good first to understand and see the stack trace to see what's causing the exception