Eunit: {node, ... instantiator broken in OTP-28.x

rlipscombe · February 28, 2026, 3:25pm

Looking at eunit/examples/eunit_examples.erl at master · richcarl/eunit · GitHub , it seems like eunit’s {node, Node, …} generator was expected to pass the full node name to the instantiator.

In OTP-27.x, this was true.

In OTP-28.x – when the new peer module was used, this was changed – the function now receives {Pid, WasNetStarted}. It’s not clear whether this change was intentional, or what the Pid refers to.

So: how does one receive the fully-qualified name of the new node, in order to use it in the tests?

williamthome · March 1, 2026, 3:21pm

Please verify if this PR resolves the issue:

github.com/erlang/otp

eunit: Pass node name to {node, ...} instantiator (#10788)

master ← williamthome:eunit/fix-node-instantiator

opened 03:19PM - 01 Mar 26 UTC

williamthome

+54 -29

The migration from slave to peer in OTP-28 discarded the node name returned by p…eer:start_link/1, passing the Pid to the instantiator instead of the node name. This made {node, ...} unusable since the instantiator needs the node name to use with {spawn, Node, Tests} or erpc:call/4. Capture the node name and wrap the instantiator so it receives the node name as an atom. Restore auto-start of net_kernel for non-distributed nodes so {node, ...} works out of the box.