RSpec timeout configuration inheritance behavior change in version 3.8

In RSpec 3.8, global timeout configurations do not inherit down to nested example groups or individual examples. If a global timeout is defined in the configuration block, it does not automatically apply to child groups; each group or example must explicitly declare its own :timeout metadata to enforce a limit.

Current Behavior and Constraints

The timeout feature allows you to set a limit that triggers a Timeout::Error when exceeded. However, the current implementation treats the global setting and metadata-based settings as distinct. If a child group omits the :timeout metadata, it effectively runs without a timeout, regardless of whether a global limit was defined in spec_helper.rb.

Likely Technical Explanation

This behavior is a result of how RSpec handles metadata merging. While many configuration options propagate, the timeout mechanism in version 3.8 was designed to rely on explicit metadata triggers. Implementing automatic inheritance would require a change to the internal metadata resolution logic to prioritize a global fallback when specific metadata is absent, a change the core team has noted would likely require an explicit configuration flag to avoid unexpected failures in legacy suites.

Verification Steps

To verify this behavior in your environment, you can use the following scoped test case:

1. Define a global timeout in your spec_helper.rb:

   RSpec.configure do |config|
     config.timeout = 1
   end

2. Create a spec with a nested group that lacks timeout metadata:

   RSpec.describe "Inheritance Test" do
     context "nested group" do
       it "should fail if inheritance worked" do
         sleep 2 # This will NOT trigger a Timeout::Error
       end
     end
   end

3. Run the spec. The example will complete successfully, confirming that the global timeout was not inherited.
4. Add timeout: 0.5 to the it block and re-run; the example will now fail as expected.

Recommendation

Until a configurable inheritance flag is introduced, you must explicitly apply :timeout metadata to every example group or example that requires a limit. To ensure consistency across a suite, consider creating a custom metadata tag or a shared context that applies the desired timeout to all included groups.

Diagnostic Detail Needed: Are you utilizing any third-party RSpec plugins for timeout management (such as rspec-timeout) alongside the native 3.8 configuration? This may alter how metadata is merged.