affected

Overview ¶

affected prints the Go packages whose test outcome could change given what differs between the working tree and a base ref, the way `nx affected` scopes a JavaScript monorepo. It is the default scope for `make test`, the git hooks, the red and coverage sweeps, and CI's pull-request run; `scripts/test-all.sh` and GOFASTR_TEST_ALL=1 are the explicit "test everything" spellings.

A package is affected when any of these hold:

• a changed file sits in the package's directory or anywhere below it that is not itself a package (testdata, embedded assets, fixtures);
• the package imports an affected package, transitively (go list's Deps);
• the package's test files import an affected package (TestImports and XTestImports, whose own transitive deps the first rule covers).

Some changes make the graph meaningless and widen the set to every package: go.mod, go.sum, go.work, and this tool's own source. A base ref that cannot be resolved, or a merge base that cannot be computed, also widens to everything, so a misconfigured checkout degrades to the full run and never to a skipped one. -all-if-changed adds callers' own triggers (the vet step passes internal/analyzers: a new rule can flag code nobody touched).

The change set is the working tree against the merge base of HEAD and the base ref: staged, unstaged and untracked files all count, and a deleted file still marks the package it left. With -diff-base the base ref is diffed directly instead; CI uses that with the pull request's base SHA, where the checkout is the PR's merge commit and no history is fetched.

Usage:

go run ./cmd/affected                         # one import path per line
go run ./cmd/affected -format dir             # ./relative/dir per line
go run ./cmd/affected -- go test -short       # run with the set appended
go run ./cmd/affected -tags red -format dir
go run ./cmd/affected -exclude 'examples/site$' -- go test -p 2
go run ./cmd/affected -match '/framework(/|$)' -- go test
go run ./cmd/affected -coverage-dir           # where wrapped commands keep coverage manifests

With a command after `--`, an empty set skips the command and exits 0 with a note on stderr: `go test` with no packages would test the current directory, which is never what a caller meant. The command's own exit code is propagated otherwise.

The affected set is the first half of what nx affected does; Go's test cache is the second. A package in the set whose binary and recorded inputs (files read, env vars) match a previous pass replays "(cached)" instead of running. That only holds while tests read nothing the suite itself rewrites, so the wrapped command gets GOFASTR_AXE_COVERAGE_DIR pointed outside the module (see commandEnv), and CI fails a second run over the same tree that re-runs any package (scripts/test-cache-replay.sh).

Environment:

GOFASTR_TEST_ALL=1             every package, no graph walk (same as -all)
GOFASTR_AFFECTED_BASE          base ref when -base is not given
GOFASTR_AFFECTED_DIFF_BASE=1   same as -diff-base

Without a base, origin/main is used when that ref exists, then main.

Exits 0 on success (including an empty set), 2 on infrastructure error, or with the wrapped command's status.