acc: surface tool-version checks as a TestAccept/prerequisites subtest

acceptance/acceptance_test.go

@@ -191,17 +191,22 @@ func hasRunFilter() bool {
 // requirePrerequisites verifies external tool prerequisites before doing any
 // work, so a stale toolchain fails fast with an actionable message instead of
 // producing confusing diffs deep into the run.
-func requirePrerequisites(t *testing.T) {
-	// Scripts use jq 1.7 features (the pick/1 builtin and the `.foo.[]` iteration syntax).
-	internal.RequireJQ(t, "1.7")
-	// uv builds the databricks-bundles wheel and provides the test interpreter
-	// via `uv python find`, which landed in the 0.3 line.
-	internal.RequireUV(t, "0.4")
-	// ruff 0.9.1 is pinned across the repo (python/pyproject.toml, Taskfile.yml);
-	// the check-formatting test's golden output assumes its formatter behavior.
-	internal.RequireRuff(t, "0.9.1")
-	// Acceptance scripts import the stdlib tomllib module, added in Python 3.11.
-	internal.EnsurePython(t, "3.11")
+//
+// It reports whether all checks passed; a failure surfaces as
+// TestAccept/prerequisites rather than a bare TestAccept.
+func requirePrerequisites(t *testing.T) bool {
+	return t.Run("prerequisites", func(t *testing.T) {
+		// Scripts use jq 1.7 features (the pick/1 builtin and the `.foo.[]` iteration syntax).
+		internal.RequireJQ(t, "1.7")
+		// uv builds the databricks-bundles wheel and provides the test interpreter
+		// via `uv python find`, which landed in the 0.3 line.
+		internal.RequireUV(t, "0.4")
+		// ruff 0.9.1 is pinned across the repo (python/pyproject.toml, Taskfile.yml);
+		// the check-formatting test's golden output assumes its formatter behavior.
+		internal.RequireRuff(t, "0.9.1")
+		// Acceptance scripts import the stdlib tomllib module, added in Python 3.11.
+		internal.RequirePython(t, "3.11")
+	})
 }
 
 func testAccept(t *testing.T, inprocessMode bool, singleTest string) int {
@@ -245,7 +250,14 @@ func testAccept(t *testing.T, inprocessMode bool, singleTest string) int {
 		os.Unsetenv(v) //nolint:usetesting // t.Setenv cannot unset
 	}
 
-	requirePrerequisites(t)
+	if !requirePrerequisites(t) {
+		// Don't run the suite against a stale toolchain; the failed subtest
+		// has already marked the parent test as failed.
+		return 0
+	}
+	// Run after the version check passed; must use the top-level t so the PATH
+	// change survives for the rest of the run.
+	internal.ConfigurePython(t, "3.11")
 
 	buildDir := getBuildDir(t, cwd, runtime.GOOS, runtime.GOARCH)
 

acceptance/internal/python.go

@@ -11,14 +11,12 @@ import (
 	"golang.org/x/mod/semver"
 )
 
-// EnsurePython makes `python3` on PATH resolve to a Python >= minVersion (e.g.
-// "3.11"). Acceptance scripts invoke `python3` directly and some import stdlib
-// modules added in newer versions, but a host's default python3 may be older.
-// On non-Windows hosts uv (see RequireUV) selects a compatible interpreter,
-// which we symlink as python3/python into a temp dir prepended to PATH. On
-// Windows os.Symlink needs extra privileges, so we instead require that the
-// python3 already on PATH satisfies the floor.
-func EnsurePython(t *testing.T, minVersion string) {
+// RequirePython fails the test if no Python >= minVersion (e.g. "3.11") is
+// available for the acceptance suite. It only verifies; ConfigurePython performs
+// the PATH setup. On Windows os.Symlink needs extra privileges, so we require the
+// python3 already on PATH to satisfy the floor; elsewhere uv must be able to find
+// a compatible interpreter.
+func RequirePython(t *testing.T, minVersion string) {
 	if runtime.GOOS == "windows" {
 		out, err := exec.Command("python3", "--version").Output()
 		if err != nil {
@@ -31,6 +29,27 @@ func EnsurePython(t *testing.T, minVersion string) {
 		return
 	}
 
+	if _, err := exec.Command("uv", "python", "find", ">="+minVersion).Output(); err != nil {
+		t.Fatalf("uv could not find python >= %s: %v", minVersion, err)
+	}
+}
+
+// ConfigurePython makes `python3` on PATH resolve to a Python >= minVersion for
+// the rest of the run. Acceptance scripts invoke `python3` directly and some
+// import stdlib modules added in newer versions, but a host's default python3
+// may be older. On non-Windows hosts uv (see RequireUV) selects a compatible
+// interpreter, which we symlink as python3/python into a temp dir prepended to
+// PATH. On Windows we rely on the python3 already on PATH, which RequirePython
+// has verified satisfies the floor.
+//
+// It must run on the top-level test's t: the t.Setenv and t.TempDir below are
+// undone when that test returns, so calling it from a subtest would revert the
+// PATH change before the rest of the suite runs.
+func ConfigurePython(t *testing.T, minVersion string) {
+	if runtime.GOOS == "windows" {
+		return
+	}
+
 	out, err := exec.Command("uv", "python", "find", ">="+minVersion).Output()
 	if err != nil {
 		t.Fatalf("uv could not find python >= %s: %v", minVersion, err)

acceptance/internal/python_test.go

@@ -16,12 +16,13 @@ func TestPythonVersionOK(t *testing.T) {
 	assert.False(t, pythonVersionOK("garbage", "3.11"))
 }
 
-func TestEnsurePython(t *testing.T) {
+func TestConfigurePython(t *testing.T) {
 	if _, err := exec.LookPath("uv"); err != nil {
 		t.Skip("uv not installed")
 	}
 
-	EnsurePython(t, "3.11")
+	RequirePython(t, "3.11")
+	ConfigurePython(t, "3.11")
 
 	// After setup, the python3 resolved from PATH must satisfy the floor.
 	out, err := exec.Command("python3", "-c", "import sys; print(sys.version_info >= (3, 11))").Output()