Why: every Go run printed "No coverage data for <file>; its sites are
uncovered". `go test -coverprofile` keys files by import path
(`github.com/acme/tool/cmd/tool/main.go`); mutator looked them up by
absolute disk path (`/.../tool/cmd/tool/main.go`). Neither path ends with
the other, so no Go file ever matched and only --no-coverage ran sites.
What: `_go_lines` asks crapper's `go_import_name` for the profile's name
of the file (nearest go.mod module line plus path inside the module) and
`_lookup` tries that name as an exact key, then the existing suffix
match. Other languages pass no name and are unchanged. Needs crapper
c757ec7 or later.
Proof: two new specs (module at the root, module in a subdirectory with
a different name) failed with None first, now pass; 78 pass. crapper:
_go_lines 6.0, covered_lines 5.0, _lookup 4.0. dryer: no candidates.
mutator on the changed lines: one equivalent survivor (insert(0) vs
insert(1)) removed by appending the name; no survivors left.
A package path is one argument. Git status uses NUL records and returns git's status. A failed coverage command leaves reports unread, coverage keeps the longest path match, and site walks no longer recurse.
Node resolves a relative import from the real path of the module. A symlinked test was loading the original source, so every mutant survived. Modules that reach the file under test are now real copies in the overlay.
Each worker keeps a private copy of the file under test and links the rest of the project, so the original tree stays put. The default is one worker per core, and --max-workers can set a lower cap.
Robert C. Martin