Keep Go's build cache between builds (closes #124)

make test and make build in the Dockerfile now share one Go build cache,
kept in a BuildKit cache mount with this repository's own id, so they
compile only what changed. script/test passes -count=1.

Model: opus-5-5

Dockerfile

@@ -50,7 +50,12 @@ ARG CHECK_EPOCH
 
 COPY . .
 
-RUN make test
+# This cache mount keeps Go's build cache between builds for make test and
+# make build; -count=1 in script/test keeps test results out of it. Go's cache
+# does not notice C header changes, so the mount has its own id: change the id
+# when the C packages installed above change.
+RUN --mount=type=cache,id=sneak/secret/go-build,target=/root/.cache/go-build \
+    make test
 
 # The version stamped into the binary: the VERSION build argument when one
 # is given, otherwise `git describe --tags --always` of the .git the build
@@ -58,7 +63,8 @@ RUN make test
 # one, the short commit when no tag is reachable. A context that carries .git
 # and still yields no version fails the build.
 ARG VERSION
-RUN version="${VERSION:-$(git describe --tags --always)}"; \
+RUN --mount=type=cache,id=sneak/secret/go-build,target=/root/.cache/go-build \
+    version="${VERSION:-$(git describe --tags --always)}"; \
     if [ -e .git ] && { [ -z "$version" ] || [ "$version" = dev ] || \
         [ "$version" = unknown ]; }; then \
         echo "no version could be derived although the build context carries .git" >&2; \

README.md

@@ -604,7 +604,8 @@ provide:
 - `script/build` — build the `secret` binary into the repo root, stamping the
   version (`VERSION` from the environment, else `git describe`) and the git
   commit
-- `script/test` — run `go vet` and the test suite (verbose rerun on failure)
+- `script/test` — run `go vet` and the test suite (verbose rerun on failure),
+  every test on every run, never a result from Go's test cache
 - `script/lint` — run `golangci-lint` in docker only: builds `Dockerfile.lint`,
   where the linter is a build step that runs on every call, also on an unchanged
   tree
@@ -624,7 +625,8 @@ provide:
 - `script/cibuild` — CI entrypoint: `docker build --ulimit memlock=-1:-1 .`
   (memguard needs mlock; the Dockerfile runs the checks), with a new
   `CHECK_EPOCH` build argument on every run so the checks run again on an
-  unchanged tree
+  unchanged tree; the `Dockerfile` keeps Go's build cache between builds, so
+  `make test` and `make build` compile only what changed
 - `script/precommit` — pre-commit checks: `go mod tidy` verification, then
   `script/check`
 - `script/install-precommit` — install the git pre-commit hook that runs

TODO.md

@@ -18,20 +18,44 @@ https://git.eeqj.de/sneak/secret/milestone/12
 
 # Completed Steps
 
+- 2026-10-06: `make test` in `script/cibuild` no longer compiles the standard
+  library and every dependency from nothing on every build
+  (https://git.eeqj.de/sneak/secret/issues/124). The `Dockerfile` runs it and
+  `make build` with Go's build cache in a BuildKit cache mount, which docker
+  keeps between builds, so each compiles only what changed since the last build.
+  The mount has an id of its own, so other repositories' builds do not share it.
+  `script/test` passes `-count=1`, so every test runs on every build and no
+  result comes from Go's test cache. A build with an empty cache, such as the
+  first after docker's build cache is cleared, compiles everything in
+  `make test` as before.
+- 2026-10-06: `TestRemoveIgnoresTerminalOnStdout` and
+  `TestRemoveAsksAtTerminalOnStdin` no longer wait until Go's test timeout
+  (https://git.eeqj.de/sneak/secret/issues/126). On Linux, `pty.Open` of
+  `github.com/creack/pty` v1.1.24 passed the address of a local variable to the
+  `ioctl` system call as a plain number, through a function call; when Go moved
+  the goroutine's stack in between, the kernel wrote the terminal's number to
+  the old place, and `pty.Open` opened `/dev/pts/0` instead of the terminal it
+  had created. `secret rm` then wrote to that other terminal, and the test read
+  a terminal no program had open, which never ends. `go.mod` now requires the
+  commit on that library's main branch that passes a pointer instead; no release
+  has it yet. Both tests stop reading the terminal when their one-minute context
+  ends and fail saying so.
 - 2026-10-06: The tests run quickly with the race detector on
   (https://git.eeqj.de/sneak/secret/issues/120). Most of their time went to
   deriving keys from passphrases with scrypt, which is slow on purpose. The new
   `secret.ScryptWorkFactor`, when not zero, replaces age's scrypt work factor
   when a passphrase encrypts; the tests of `internal/secret`, `internal/vault`
   and `internal/cli` set it to 1 before any test runs, and the program never
-  sets it. `TestRemovalAsksWithoutHoldingLock` and
+  sets it; `TestGetCommandOutputsToStdout` checks that the passphrase unlocker
-  `TestFailedCommandReleasesLock` no longer run in parallel with other tests:
+  the built binary's `secret init` writes names age's work factor, 18.
-  each waits at most 10 seconds for the in-memory lock that every test in the
+  `TestRemovalAsksWithoutHoldingLock` and `TestFailedCommandReleasesLock` no
-  package shares, and other tests' commands held it longer.
+  longer run in parallel with other tests: each waits at most 10 seconds for the
-  `TestConcurrentAddsKeepEveryVersion`, which times nothing, and
+  in-memory lock that every test in the package shares, and other tests'
-  `TestGetCommandOutputsToStdout`, which no longer sets an environment variable
+  commands held it longer. `TestConcurrentAddsKeepEveryVersion`, which times
-  its commands do not read, now run in parallel. The `script/cibuild` comment no
+  nothing, and `TestGetCommandOutputsToStdout`, which no longer sets an
-  longer says that tests are skipped without its memlock ulimit.
+  environment variable its commands do not read, now run in parallel. The
+  `script/cibuild` comment no longer says that tests are skipped without its
+  memlock ulimit.
 - 2026-10-05: No test stores a secret larger than 1 MiB
   (https://git.eeqj.de/sneak/secret/issues/52). The size tests for `secret add`,
   `secret import` and the stdin buffer no longer try 2 MB, 10 MB, 99 MB, 100 MB

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/btcsuite/btcd/btcec/v2 v2.1.3
 	github.com/btcsuite/btcd/btcutil v1.1.6
 	github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d
-	github.com/creack/pty v1.1.24
+	github.com/creack/pty v1.1.25-0.20260601142114-9246436fffe8 // v1.1.24's Open can return another pty's terminal
 	github.com/dustin/go-humanize v1.0.1
 	github.com/fatih/color v1.18.0
 	github.com/keybase/go-keychain v0.0.0-20230307172405-3e4884637dd1

go.sum

@@ -35,8 +35,8 @@ github.com/btcsuite/snappy-go v1.0.0/go.mod h1:8woku9dyThutzjeg+3xrA5iCpBRH8XEEg
 github.com/btcsuite/websocket v0.0.0-20150119174127-31079b680792/go.mod h1:ghJtEyQwv5/p4Mg4C0fgbePVuGr935/5ddU9Z3TmDRY=
 github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46fmI40EZs=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
-github.com/creack/pty v1.1.24 h1:bJrF4RRfyJnbTJqzRLHzcGaZK1NeM5kTC9jGgovnR1s=
+github.com/creack/pty v1.1.25-0.20260601142114-9246436fffe8 h1:CY3gjC7naqYGLMiywvj3suPfa1i0p/QEr7o8ujxL/2M=
-github.com/creack/pty v1.1.24/go.mod h1:08sCNb52WyoAwi2QDyzUCTgcvVFhUzewun7wtTfvcwE=
+github.com/creack/pty v1.1.25-0.20260601142114-9246436fffe8/go.mod h1:08sCNb52WyoAwi2QDyzUCTgcvVFhUzewun7wtTfvcwE=
 github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=

internal/cli/integration_test.go

@@ -2601,7 +2601,12 @@ func TestRemoveWithoutTerminalFailsAtOnce(t *testing.T) {
 // and stderr, not both: whether it asks must depend on stdin alone, where
 // the answer is read from. pty.Open returns the two ends of a new terminal:
 // tty is the end a program uses as its terminal, and ptmx the end the test
-// reads what the terminal shows from and types into.
+// reads what the terminal shows from and types into. Reading ptmx stops at
+// the context's deadline, when secret rm is killed too, so a terminal that
+// stays open fails the test then instead of hanging it. The deadline works
+// only while ptmx stays non-blocking, as pty.Open of the github.com/creack/pty
+// commit in go.mod leaves it: calling ptmx.Fd() or going back to v1.1.24
+// makes the read ignore the deadline, without any error.
 
 // TestRemoveIgnoresTerminalOnStdout runs `echo y | secret rm x` at a
 // terminal. stdin is a pipe, so nobody can answer there, and the command
@@ -2619,6 +2624,9 @@ func TestRemoveIgnoresTerminalOnStdout(t *testing.T) {
 
 	defer func() { _ = ptmx.Close() }()
 
+	deadline, _ := ctx.Deadline()
+	require.NoError(t, ptmx.SetReadDeadline(deadline))
+
 	cmd.Stdin = strings.NewReader("y\n")
 	cmd.Stdout = tty
 	cmd.Stderr = tty
@@ -2628,9 +2636,15 @@ func TestRemoveIgnoresTerminalOnStdout(t *testing.T) {
 	_ = tty.Close()
 
 	// The read ends once secret rm has exited and so closed the terminal.
-	shown, _ := io.ReadAll(ptmx)
+	shown, err := io.ReadAll(ptmx)
+	require.NotErrorIs(t, err, os.ErrDeadlineExceeded,
+		"the terminal was still open a minute after secret rm started: %s",
+		shown)
 
-	require.Error(t, cmd.Wait())
+	err = cmd.Wait()
+
+	require.NoError(t, ctx.Err(), "secret rm did not exit within a minute")
+	require.Error(t, err)
 	assert.Contains(t, string(shown), "pass --force")
 	assert.DirExists(t, secretDir)
 }
@@ -2650,6 +2664,9 @@ func TestRemoveAsksAtTerminalOnStdin(t *testing.T) {
 
 	defer func() { _ = ptmx.Close() }()
 
+	deadline, _ := ctx.Deadline()
+	require.NoError(t, ptmx.SetReadDeadline(deadline))
+
 	cmd.Stdin = tty
 	// Not a file, so exec.Cmd connects stdout through a pipe.
 	cmd.Stdout = io.Discard
@@ -2667,7 +2684,8 @@ func TestRemoveAsksAtTerminalOnStdin(t *testing.T) {
 	terminal := bufio.NewReader(ptmx)
 	for !bytes.HasSuffix(shown, []byte("[y/N] ")) {
 		char, err = terminal.ReadByte()
-		require.NoError(t, err, "secret rm ended without asking: %s", shown)
+		require.NoError(t, err, "secret rm did not ask on the terminal: %s",
+			shown)
 
 		shown = append(shown, char)
 	}

internal/cli/stdout_stderr_test.go

@@ -41,6 +41,18 @@ func TestGetCommandOutputsToStdout(t *testing.T) {
 	output, err := cmd.CombinedOutput()
 	require.NoError(t, err, "init should succeed: %s", string(output))
 
+	// The binary, unlike these tests, encrypts the passphrase unlocker's key
+	// at age's scrypt work factor, 18. age writes the work factor last on the
+	// second line of priv.age: "-> scrypt <salt> <work factor>".
+	vaultDir := filepath.Join(tempDir, "vaults.d", "default")
+	unlockerName := readFile(t, filepath.Join(vaultDir, "current-unlocker"))
+	unlockerDir := filepath.Join(vaultDir, "unlockers.d", string(unlockerName))
+	privAge := readFile(t, filepath.Join(unlockerDir, "priv.age"))
+	header := strings.SplitN(string(privAge), "\n", 3)
+	require.Len(t, header, 3, "priv.age should start with an age header")
+	assert.Regexp(t, `^-> scrypt \S+ 18$`, header[1],
+		"the passphrase unlocker should be encrypted at scrypt work factor 18")
+
 	// Add a secret
 	//nolint:gosec // G204: test executes the freshly built secret binary
 	cmd = exec.CommandContext(t.Context(), secretPath, "add", "test/secret")

script/cibuild

@@ -6,7 +6,8 @@
 # the lower limit of a plain `docker build .`.
 # A cached build checks nothing: a new CHECK_EPOCH on every run makes the
 # Dockerfile's check steps run again on an unchanged tree, while its base
-# images and module downloads stay cached.
+# images, module downloads and the Go build cache that make test and make
+# build use stay cached.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"

script/test

@@ -9,7 +9,9 @@ main() {
     # CGO is required (Makefile exports this too)
     export CGO_ENABLED=1
     go vet ./...
-    go test ./... || go test -v ./...
+    # -count=1: run every test, never take a result from Go's test cache,
+    # which the Dockerfile keeps between builds
+    go test -count=1 ./... || go test -count=1 -v ./...
 }
 
 main "$@"