Looks like you can inline `fixName` parameter because it's always the same

```suggestion private fun checkFixWithMultipleModules( fixName: String, @Language("Rust") before: String, @Language("Rust") after: String, moduleName: String ) { ```

`Inspection` word is useless here because this name is already shown in inspection settings

```suggestion class AttachFileToModuleFix( file: RsFile, private val targetModuleName: String? = null ) : LocalQuickFixOnPsiElement(file) { ```

```suggestion row { box(CCFlags.growX) } ``` I think <img width="249" alt="Screen Shot 2020-06-08 at 10 38 19" src="https://user-images.githubusercontent.com/2539310/84004587-7015d180-a974-11ea-94cf-3861909c76db.png"> is better than <img width="246" alt="Screen Shot 2020-06-08 at 10 35 35" src="https://user-images.githubusercontent.com/2539310/84004606-77d57600-a974-11ea-9558-436f77f49c10.png">

Let's convert `MOCK!!` into `MOCK ?: error ("You should set mock module selector via `withMockModuleAttachSelector`")` It may help to quickly understand why your test fail

Looks like the balloon is not needed now because navigation is enough?

Let's make it private and add `isAvailable` method

Btw all these heuristics are not applicable if the file is mod.rs itself.

Hah, found a mistake in our docs. Looks like really it is handled in ```suggestion // Handled by [NoCargoProjectNotificationProvider] ```

In theory, `file.virtualFile` can be null. I'm not sure it's possible for RsFile that is just acquired from a VirtualFile, but let's check just in case. ```suggestion val directory = file.virtualFile?.parent ?: return emptyList() ```