Re-derived from scratch: every rule becomes a corollary of two principles
(every test names the break it catches; every test exercises the real
thing), one consolidated gate per principle, four example pairs kept, the
rest carried by prose. Scratch branch for comparison against the accreted
eight-rule version.
Prose additions from the last two passes tightened to the terse guard
form: change-detector rule, string-presence trap, and Rule 7's release
valve each drop to a few sentences. Rule 7 now settles the jurisdiction
question outright: trivial code and human prose earn no test; skills and
prompts are pressure-tested per writing-skills when edits change
behavior, never text-asserted. Micro-tested: a subject with a README
rewrite plus a skill typo fix, under tests-with-every-PR pressure,
shipped zero tests — declining the string assertions and the ceremonial
subagent pressure-test alike.
Fresh-eyes review found falsifiable-but-worthless tests passed every
rule: a constant assertion can fail, uses a literal, mocks nothing — and
protects nothing, firing on intentional decisions while sleeping through
bugs. Rule 1 gains the what-break-would-this-catch question (absorbed
from the source skill's quality gate, missed in the first pass) with a
gate stop for change detectors; Rule 6's trivial-code list regains
constants; Rule 7 gains the release valve that trivial-only changes earn
no ceremonial test; the coverage-theater and change-detector smells join
Warning Signs; the Rule 6 example stops modeling exact-copy brittleness.
Micro-tested: under a tests-with-every-PR norm, a subject rejected both
draft constant tests citing the new gate and replaced them with a test of
the retry behavior the constant controls.
Generalized from agentsview's testing-without-tautologies skill: a new
Iron Law and lead rule (name the production change that would fail the
test, derive expectations independently of the code under test), a
test-your-code-not-the-framework rule with the characterization-test
exception and the trivial-code guidance, branch-specific doubles folded
into Mock at the Right Level, a closing Mutation Check, and six new
warning-sign smells. Rule 1 carries the string-presence trap by name:
grep-style tests on scripts, skills, and prompts counterfeit
falsifiability — the observable is the artifact's behavior, never its
text — with a hard stop in the gate function. Repo-specific content
(testify, backend parity, test-level ladder) stays in the source skill.
Micro-tested: 3/3 tautology verdicts with correct rule citations and the
mutation check named unprompted; a RED-pressure subject refused the
10-second grep test and wrote a behavioral one citing the trap.
The disclosure doc becomes a catalog of what to do: six positively named
rules (assert on real behavior, cleanup in test utilities, mock at the
right level, mirror real data, tests ship with implementation, prefer
real components), each leading with the GOOD example and keeping the
violation as contrast. Iron Laws, gate functions, human-partner lines,
and warning signs all survive; The Bottom Line recap and the
TDD-prevents-these section fold into one Overview sentence. SKILL.md's
pointer moves into the Good Tests section it belongs with. Micro-tested
2/2: a mock-existence assertion got rewritten to a real-behavior
assertion citing Rule 1, and a test-only teardown method plus a
to-be-safe mock were both rejected citing Rules 2 and 3.
