`[[ -n "${ECC_PYTEST_CMD:-}" ]]` asked whether the variable had a value, not
whether it was set, so `ECC_PYTEST_CMD=` fell through to virtualenv discovery
while `ECC_PYTEST_CMD=" "` failed the push. Two spellings of the same mistake,
two behaviours. Falling through is the wrong one: an override that evaluated to
nothing -- a command substitution that found no pytest, say -- then silently ran
a different runner than the operator named, which is exactly the substitution
this resolver refuses to make anywhere else. Both now fail closed.
`${ECC_PYTEST_CMD+set}` rather than `[[ -v ECC_PYTEST_CMD ]]`, because `-v` is
bash 4.2 and a stock macOS /bin/bash is 3.2, where it is not a false but a
syntax error. The hook runs under whatever `env bash` resolves to.
The override is still not probed -- probing runs the operator's command, and a
wrapper that ignores `--version` executes the whole suite and is then rejected
for not printing a version. What the gate can honestly do about a stale override
is refuse to be quiet about it, so a push that uses one now says so, every time,
and says the hook has not checked that it is pytest. A bypass that announces
itself is not the silent gate this resolver exists to prevent.
The fixture env is built from nothing instead of inheriting process.env with two
keys blanked. Blanking is no longer neutral: a blanked ECC_PYTEST_CMD is now an
override, and every one of these tests would have taken that branch.
Juan Garibay
08b173f12f