How to Fix a Unity Test Assembly That Cannot See Runtime Code

A test asmdef is an isolated compilation unit. If it does not explicitly reference the assembly that contains your gameplay code, those types simply do not exist from its point of view.

How to fix it

1. Reference the runtime asmdef

Open the test asmdef inspector and add your gameplay asmdef under Assembly Definition References. Without it, the test cannot name a single type from that assembly.

2. Add the test framework references

Ensure UnityEngine.TestRunner and UnityEditor.TestRunner are referenced and that Test Assemblies is checked, which auto-adds the nunit and test runner precompiled references.

3. Check platform and define constraints

If the runtime asmdef is editor-only or guarded by a define the test asmdef does not share, the reference resolves to nothing. Align the platforms and define constraints between them.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unity error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.