Lint and test as phases of the Dockerfile (closes #38)

Linting and testing are now the lint and test phases of the one
Dockerfile, and the build stage copies a file from each, so a plain
docker build . cannot pass while either fails. Dockerfile.lint is gone.
REPO_POLICIES.md, script/lint, script/test, script/docker and
script/cibuild are the current copies from the next branch of
sneak/prompts: every docker build there is uncached and tagged,
script/test builds the test phase instead of running go vet and go test
on the host, and script/cibuild bootstraps, runs script/check, then
builds the image with the version from the host. The test phase
installs gcc and musl-dev because -race needs cgo. The version stamping
is unchanged. The issue's line leaves the README TODO list.

Model: opus-5-5

script/bootstrap

@@ -3,9 +3,9 @@
 # repo. Idempotent: every install is guarded by a check, so tools that
 # are already there are left alone. Base tooling comes from nix, apt,
 # brew, or apk, detected in that order, and nothing is assumed to be
-# present. The linter is not installed here: it only ever runs inside
-# the image built from Dockerfile.lint, so Docker is what is needed for
-# it, and that is checked for rather than installed.
+# present. The linter is not installed here: linting and testing run
+# only as phases of the Dockerfile, so Docker is what is needed for
+# them, and that is checked for rather than installed.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
@@ -60,7 +60,7 @@ main() {
     go mod download
 
     if missing docker; then
-        echo "bootstrap: docker is not installed; make lint needs it" >&2
+        echo "bootstrap: docker is not installed; make lint and make test need it" >&2
     fi
 
     echo "bootstrap complete"

script/cibuild

@@ -1,8 +1,10 @@
 #!/bin/sh
-# script/cibuild: run the CI build. The linter needs an image of its
-# own, so it runs first; the Dockerfile then runs the formatting check,
-# the tests and the build, so a green run here means make check is
-# green.
+# script/cibuild: run the CI build. It bootstraps first: a CI runner
+# checks out and runs this and nothing else, and script/fmt-check runs
+# the formatter on the host, which a pristine checkout cannot do.
+# --no-cache for the same reason as script/docker: the gate phases the
+# final stage depends on are RUN steps, and a cached one is a check that
+# did not run.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -10,8 +12,17 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    "$SCRIPT_DIR/lint"
-    docker build .
+    "$SCRIPT_DIR/bootstrap"
+    "$SCRIPT_DIR/check"
+    # Own line: a failing command substitution inside an argument does
+    # not trip `set -e`, so the inline form degrades silently to an
+    # empty constant. The VERSION build argument takes precedence over
+    # the version a build stage derives from the .git in the context.
+    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
+    [ -n "$version" ] || version="unknown"
+    docker build --no-cache \
+        --build-arg VERSION="$version" \
+        -t "$("$SCRIPT_DIR/projectname")" .
 }
 
 main "$@"

script/docker

@@ -1,6 +1,8 @@
 #!/bin/sh
 # script/docker: build the Docker image tagged with the project name.
 # Identical in all repos; the tag comes from script/projectname.
+# --no-cache because the gate phases the final stage depends on are RUN
+# steps, and a cached one is a check that did not run.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -8,7 +10,15 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build -t "$("$SCRIPT_DIR/projectname")" .
+    # Own line: a failing command substitution inside an argument does
+    # not trip `set -e`, so the inline form degrades silently to an
+    # empty constant. The VERSION build argument takes precedence over
+    # the version a build stage derives from the .git in the context.
+    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
+    [ -n "$version" ] || version="unknown"
+    docker build --no-cache \
+        --build-arg VERSION="$version" \
+        -t "$("$SCRIPT_DIR/projectname")" .
 }
 
 main "$@"

script/lint

@@ -1,9 +1,13 @@
 #!/bin/sh
-# script/lint: run the linter. Linting only ever happens inside the
-# image built from Dockerfile.lint, which pins the linter by hash, so
-# the answer is the same on every machine and in CI. The linter runs as
-# a build step of that image, so a complaint fails the build and no
-# container is left behind.
+# script/lint: run the linter. Linting is a phase of the Dockerfile and
+# this builds that phase alone; the linter is never installed or run on
+# a developer host, where a shared result cache and a host-global lock
+# make its answer untrustworthy.
+#
+# The phase is not the last stage in the file, so it is built only when
+# --target names it. --no-cache because a cached lint layer is a lint
+# that did not run. The tag makes each build replace the previous image
+# instead of leaving a dangling one behind.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -11,7 +15,8 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build --progress=plain -f Dockerfile.lint \
+    docker build --no-cache \
+        --target lint \
         -t "$("$SCRIPT_DIR/projectname")-lint" .
 }
 

script/test

@@ -1,13 +1,19 @@
 #!/bin/sh
-# script/test: run the test suite (vet first, verbose rerun on failure).
+# script/test: run the test suite. Testing is a phase of the Dockerfile
+# and this builds that phase alone, on the same terms as script/lint:
+# --target because a phase that is not the last stage is built only when
+# named, --no-cache because a cached test layer is a test that did not
+# run, and a tag so each build replaces the previous image.
 set -eu
 
-ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    go vet ./...
-    go test -timeout 90s ./... || go test -timeout 90s -v ./...
+    docker build --no-cache \
+        --target test \
+        -t "$("$SCRIPT_DIR/projectname")-test" .
 }
 
 main "$@"