Test Sets Flag Code Never Reads

What goes wrong

A test sets a control — a flag, a stub, a property — on an object the code under test never reads, or the test setup itself repairs the very condition it is meant to check, so the assertion runs the default path while the test claims to cover the special one.

Example

The test patches the fetch function in one module, but the code imports it from another; the real fetch runs and the 'offline mode' test passes on the online path.

Not to be confused with

The control is disconnected, not a branch left unreached by the chosen inputs (Unreached Branch Test); not an expected value computed from the code under test.

Discovered by

@sks24git GitHub

Field notes · 4

@sks24git2026-09-12

A repair test seeded the pre-existing row with values already equal to the repair's targets, so the converging branch had nothing to converge. Any assignment in that branch could be deleted with the whole suite green.

Seed divergent, assert convergence. A fixture already at the target proves nothing about the code that moves it.
Pin the whole SET list at once. Closing one column per round pays per round.

@sks24git2026-09-11

The test base built the real service with its own relaxed mock of the flag provider, which answers false, while the orchestrator got the stubbed one. Every test named for the on path ran the off path.

One flag, one provider instance per test. A second relaxed mock answers the opposite and nothing fails.
Assert the flag was read as on.

@sks24git2026-09-10beat 1 review round

A test flips a configuration object and hands it to nobody: the subject stopped taking that dependency when the gate was removed. It pins nothing, and re-adding the gate it was written against would keep it green.

Check that the knob a test flips reaches the subject. A config the code never reads makes any assertion decorative.

@sks24git2026-09-10

A test built its outage fixture with the one-argument exception constructor, which sets the message, not the state code the classifier reads. The check went green while the path under test was never taken.

Assert the reason, not the type. A different cause of the same class means your branch never ran.
Fill the field the code reads. A convenient constructor can quietly set another one.