fix(write-tests): boundary/wire mocking over interface fakes - #1
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ajcarberry wants to merge 1 commit into
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fix(write-tests): boundary/wire mocking over interface fakes#1ajcarberry wants to merge 1 commit into
ajcarberry wants to merge 1 commit into
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The skill taught patterns that a real Go CLI testing effort found to be anti-patterns. Bring it in line. - Replace the three-layer strategy (which framed interface-based fakes as a legitimate boundary approach) with boundary-first testing: fake the executable on PATH and assert the real argv, or httptest and assert the method/path/body. Drop the CommandRunner interface pattern — asserting "Run was called" proves the code called the fake, not that it built the right command, and it couples tests to a test-only interface. - Stop recommending t.Skip() when the binary is absent — that is a false-green (the coverage gate runs `go test` without building first). Build the binary in TestMain; a miss is a hard failure. Note that subprocess tests don't count toward a package's coverage, so command logic needs in-process cobra tests (with an os.Stdout capture helper, since commands print via fmt.Printf, not cmd.OutOrStdout). - Switch examples from testify to stdlib `testing` (t.Fatalf preconditions, t.Errorf checks, reflect.DeepEqual, errors.Is/As) to match stdlib codebases; keep a note to match testify only where a project already uses it. - Add the "prove the negative" pattern for destructive ops (fake fails the test on any mutating call) and a Determinism section (map-iteration and unseeded-RNG bugs). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01AfCuqUGhxYxbvo4FgkBtFm
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The
write-testsskill taught three things that a real Go CLI testing effort (in a downstream repo) found to be anti-patterns. This brings the skill in line with what actually works.Changes
CommandRunner,assert fake.Calls[0][0]=="nomad") proves the code called a fake, not that it built the right command, and couples tests to a test-only interface. Replaced with: fake the executable onPATHand assert the real argv (sharedinternal/testutil.FakeExec), orhttptestand assert method/path/decoded-body.t.Skip()on a missing binary. That is a false-green — if the coverage gate runsgo testwithout building first, the E2E tests silently pass.TestMainbuilds the binary; a miss is a hard failure. Added the note that subprocess tests don't count toward a package's coverage, so command logic needs in-process Cobra tests (with anos.Stdoutcapture helper, since commands print viafmt.Printf, notcmd.OutOrStdout()).testing. The reference mandated testify while the codebases it targets use stdlib. Converted the examples; kept a note to match testify only where a project already standardises on it.Kept as-is: table-driven structure, naming,
t.Helper(), golden files, TUI state-transition testing, parallelism guidance.Companion to the downstream ADR that codifies these tenets (homelab-monorepo ADR-0027).
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