ActionView::Template::Error in CI

A template raised while rendering, and ActionView wrapped it in Template::Error with the offending template and line. The wrapped exception underneath is what you actually need to fix.

What this error means

A request, system, or view spec fails with ActionView::Template::Error naming a template and line, followed by the underlying error. Common in CI when data the view assumes is absent or a helper/asset is missing.

rails

ActionView::Template::Error:
       undefined method `name' for nil:NilClass
     # ./app/views/orders/show.html.erb:4
     <h1><%= @order.customer.name %></h1>

Common causes

Missing data in the view

An instance variable or association the template uses is nil in the test setup, so a method call inside the view raises.

Missing partial or helper

A render references a partial that does not exist, or a helper method not loaded in the test context.

Asset/path helper failure

asset_path or image_tag points at an asset the test environment did not build, raising inside the template.

How to fix it

Fix the wrapped error

Read the underlying exception under the Template::Error wrapper and the cited template line.
Provide the missing data in setup, or guard nil in the view.
Add the missing partial/helper, or precompile the referenced asset for tests.

Guard nil in the template

ERB

<h1><%= @order.customer&.name %></h1>

How to prevent it

Set up complete data for view/request specs.
Use safe navigation for optional associations in templates.
Build or stub assets the view references in the test env.