A modern programming language that makes developers happier.

kotlinlang

Hey i want to test observer in mockk. Anyone know how to do that.
```viewModel.onDownloadErrorLiveData.observe(this, { consumable -&gt;
           some code
        })```

You can get a reference to arguments passed in with `capture` in a verify block or in an `answers` block. Then just manually invoke the observer.

<@UJL8PEZ1Q> thanks for your reply. I am new in this library. I didn't get the reference or example. Can you please give me the example if possible. It would be great pleasure for me.

Sorry not on a proper keyboard but I'll try... ```
```lateinit var observer : Observer
every { mockLiveData.observe(any(), any()) } answers { observer = secondArg() as Observer } ```

<@UJL8PEZ1Q>
```private fun yo(){
    viewModel.consentTag.observe(this, Observer { type -&gt;
        typeText.text = type
    })
}```
this is my function

Screenshot 2021-07-15 at 17.16.03.png

```import androidx.lifecycle.Observer```
which import i need to use

Screenshot 2021-07-15 at 17.16.57.png

```@Test
fun `yo `() {
    every { mockViewModel.consentTag.observe(any(), any()) } answers {
        observer = secondArg() as Observer
    }

}```
it giving error

you need to add the generic type of the LiveData

it fixed on complaining in observer issue

Screenshot 2021-07-15 at 17.21.01.png

yeah when you cast it using `as` you also need to define the type

or alternatively I believe `secondArg` takes a type argument, you could try putting it there

```observer = secondArg() as ConsentType```


the actual type of the lambda that you’re passing in as the second argument of the `observe` function is `Observer&lt;ConsentType&gt;` - kotlin allows you to write it as a lambda with SAM conversion

and little bit confuse
```private fun yo(){
    viewModel.consentTag.observe(this, Observer { type -&gt;
        typeText.text = type
    })
}```
how can i set value `type`  in typeText

once you have the reference to the observer you can manually invoke `onChanged`

<@UJL8PEZ1Q> like this
```@Test
    fun `yo `() {
        val value = ConsentType.GENERAL
        every { mockViewModel.consentTag.observe(any(), any()) } answers {
            observer = secondArg() as Observer&lt;ConsentType&gt;
        }
        observer.onChanged(value)
        consentActivity.yo()
        verify { mockTextView.tag = value }
    }```

it gives error `kotlin.UninitializedPropertyAccessException: lateinit property observer has not been initialized`

yeah that makes sense - the way `every` / `answers` works is that the `answers` block with be run every time the function inside of `every` gets called.  so if this `yo` function is what calls it, you need to call it in order to initialize your `observer` var

So i need to call `yo`  at top of function ?