Production default never tested

What goes wrong

Every test sets the setting explicitly, so the built-in default that decides behaviour when nothing is set is read by no test. The default can be changed or flipped and every test stays green.

Example

Every test sets retries to 3; the code's default is changed from 3 to 0 and the suite still passes.

Not to be confused with

Not a limit checked only from inside (Unchallenged Boundary Assertion) and not leaked test state (Ambient Fixture Contamination); the default value itself is simply never observed.

Discovered by

@sks24git GitHub

Field notes · 5

@sks24git2026-11-05

The image lacked a font the document builder needs, and every test pointed the builder at its own bundled font. So production made no documents at all while CI stayed green.

Test the path production takes, not only the override. If every test sets the escape hatch, the default path is never run.

@sks24git2026-10-31beat 2 review rounds

The gate tests swapped in a fake source for the new check, so nothing ran the real one by default. Make the default always pass and every test stays green while bad files go out.

Pin the default wiring, not only the function. A fixture that replaces it hides a dead check.
Test that a warning never hides an error. A stale-data note can turn red into green.

@sks24git2026-10-30beat 6 review rounds

A new mode ships switched off, and its tests take over the one test that pinned what the old default mode reports as read. The default keeps running for every user while nothing checks what it claims to have seen.

Keep the default's tests when you add a mode behind a switch. The off path is the one that runs.

@sks24git2026-09-07

A form showed a fallback default for a value the store never writes, and the only test seeded a saved value first. Change the fallback and every test stays green while the next save persists the wrong number.

Pin the empty state, not just the saved one. A default the form posts back is a write path.
Keep one spelling of a default. Four literals drift; one constant cannot.

@sks24git2026-08-22

A test suite pinned a new threshold to zero globally so old fixtures stayed green, and the feature's own test set the value it tested against. The production default ran in no test at all — retune it and the build stays green while a paid product stage silently stops being offered to anyone.

Every default must run in at least one test with the knob unset. A suite that always sets the knob tests your test, not the product.
Pin the boundary, not two far points. Values far above and below a threshold survive >= flipping to >.