Guard against invalid build outputs

Which seem to be a possibility if the job is forcefully stopped.

1 files changed, 3 insertions, 0 deletions

diff --git a/app/services/govuk_guix/build_mini_environment.rb b/app/services/govuk_guix/build_mini_environment.rb
index 9bce8b5..a0361b0 100644
--- a/app/services/govuk_guix/build_mini_environment.rb
+++ b/app/services/govuk_guix/build_mini_environment.rb
@@ -60,6 +60,9 @@ module GovukGuix::BuildMiniEnvironment
     )
 
     build_output = output.last.strip
+
+    raise 'InvalidOutput' unless build_output.starts_with? '/gnu/store'
+
     logger.debug(self.class) { "build_output: #{build_output}" }
 
     mini_environment.update(