The test suite and the shipped platform now run the same Rx

Everything in MeshWeaver is a stream. Every message a hub handles, every layout area that renders, every read and write to the mesh is built on one library — Reactive Extensions for .NET.

That library was pinned twice, in two places, at two different major versions. The product was built against Rx 6. The test suite that decides whether the product is fit to ship pulled in Rx 7, because the companion testing package it uses requires it. Nothing was red, nothing failed to restore, and nobody could see it: the two pins sit five lines apart and share no common name, so the existing check for split package families — which matches on a shared prefix — was structurally unable to relate them.

A test suite running a different major version of its most load-bearing dependency from the one that ships is the one gap a suite must never have. Both pins now read the same version, so the platform is tested on what it runs.

Rx 7 itself is a packaging release rather than a behavioural one: no public API was removed, and scheduler behaviour, error propagation and subscription disposal are unchanged — which was verified against the library's own compatibility baseline before the move, not assumed.

The check that missed this can now describe a family by naming its members rather than guessing from a shared prefix, and it carries a test that fails on exactly the pairing which was live here — a guard nobody has seen fail is not yet a guard.

The method behind both of this week's major version moves is written up under Dependency Major Upgrades.