Commit 3c2cd351 authored by Cody Hiar's avatar Cody Hiar
Browse files

Add example error message.

parent 9c292dd0

doc/builders/fetchers.chapter.md

+5 −1
Original line number Diff line number Diff line
@@ -39,7 +39,11 @@ fetchurl { 


Use the resulting error message to determine the correct hash.



<error message here>

```

error: hash mismatch in fixed-output derivation '/path/to/my.drv':

         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=

            got:    sha256-RApQUm78dswhBLC/rfU9y0u6pSAzHceIJqgmetRD24E=

```



A similar problem arises while testing changes to a fetcher's implementation. If the output of the derivation already exists in the Nix store, test failures can go undetected. The [`invalidateFetcherByDrvHash`](#tester-invalidateFetcherByDrvHash) function helps prevent reusing cached derivations.