Add subprocess runner and generated config helpers

internal/adapters/subprocess/run_test.go

@@ -0,0 +1,196 @@
+package subprocess
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+func TestRunSuccessCapturesStdoutStderr(t *testing.T) {
+	exe, err := os.Executable()
+	if err != nil {
+		t.Fatalf("os.Executable() error = %v", err)
+	}
+
+	dir := t.TempDir()
+	stdoutPath := filepath.Join(dir, "stdout.log")
+	stderrPath := filepath.Join(dir, "stderr.log")
+	req := RunRequest{
+		Executable:    exe,
+		Args:          []string{"-test.run=TestSubprocessHelper", "--", "success"},
+		EnvOverrides:  map[string]string{"GO_WANT_SUBPROCESS_HELPER": "1", "SUBPROCESS_HELPER_STDOUT": "hello-out", "SUBPROCESS_HELPER_STDERR": "hello-err"},
+		StdoutLogPath: stdoutPath,
+		StderrLogPath: stderrPath,
+	}
+
+	res, err := Run(context.Background(), req)
+	if err != nil {
+		t.Fatalf("Run() error = %v", err)
+	}
+	if res.ExitCode != 0 {
+		t.Fatalf("ExitCode = %d, want 0", res.ExitCode)
+	}
+
+	stdoutBytes, err := os.ReadFile(stdoutPath)
+	if err != nil {
+		t.Fatalf("read stdout log: %v", err)
+	}
+	if !strings.Contains(string(stdoutBytes), "hello-out") {
+		t.Fatalf("stdout log = %q, want hello-out", string(stdoutBytes))
+	}
+
+	stderrBytes, err := os.ReadFile(stderrPath)
+	if err != nil {
+		t.Fatalf("read stderr log: %v", err)
+	}
+	if !strings.Contains(string(stderrBytes), "hello-err") {
+		t.Fatalf("stderr log = %q, want hello-err", string(stderrBytes))
+	}
+}
+
+func TestRunFailureReturnsUsefulError(t *testing.T) {
+	exe, err := os.Executable()
+	if err != nil {
+		t.Fatalf("os.Executable() error = %v", err)
+	}
+
+	req := RunRequest{
+		Executable: exe,
+		Args:       []string{"-test.run=TestSubprocessHelper", "--", "fail"},
+		EnvOverrides: map[string]string{
+			"GO_WANT_SUBPROCESS_HELPER": "1",
+		},
+	}
+
+	res, err := Run(context.Background(), req)
+	if err == nil {
+		t.Fatal("Run() error = nil, want non-nil")
+	}
+	if res.ExitCode == 0 {
+		t.Fatalf("ExitCode = %d, want non-zero", res.ExitCode)
+	}
+	if !strings.Contains(err.Error(), "exit code") {
+		t.Fatalf("error = %q, want exit code context", err.Error())
+	}
+	if !strings.Contains(err.Error(), exe) {
+		t.Fatalf("error = %q, want executable context", err.Error())
+	}
+}
+
+func TestRunTimeout(t *testing.T) {
+	exe, err := os.Executable()
+	if err != nil {
+		t.Fatalf("os.Executable() error = %v", err)
+	}
+
+	req := RunRequest{
+		Executable: exe,
+		Args:       []string{"-test.run=TestSubprocessHelper", "--", "sleep"},
+		EnvOverrides: map[string]string{
+			"GO_WANT_SUBPROCESS_HELPER": "1",
+		},
+		Timeout: 50 * time.Millisecond,
+	}
+
+	res, err := Run(context.Background(), req)
+	if err == nil {
+		t.Fatal("Run() error = nil, want timeout error")
+	}
+	if !res.TimedOut {
+		t.Fatalf("TimedOut = %v, want true", res.TimedOut)
+	}
+	if !strings.Contains(err.Error(), "timed out") {
+		t.Fatalf("error = %q, want timeout context", err.Error())
+	}
+}
+
+func TestWriteYAMLAtomic(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.generated.yml")
+
+	if err := WriteYAMLAtomic(path, map[string]any{"name": "narratio", "stage": "merge"}, 0o644); err != nil {
+		t.Fatalf("WriteYAMLAtomic() error = %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read yaml: %v", err)
+	}
+
+	var got map[string]any
+	if err := yaml.Unmarshal(data, &got); err != nil {
+		t.Fatalf("yaml unmarshal: %v", err)
+	}
+	if got["name"] != "narratio" {
+		t.Fatalf("name = %#v, want narratio", got["name"])
+	}
+}
+
+func TestWriteYAMLAtomicOverwriteNoTempResidue(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.generated.yml")
+
+	if err := WriteYAMLAtomic(path, map[string]any{"value": "one"}, 0o644); err != nil {
+		t.Fatalf("first write: %v", err)
+	}
+	if err := WriteYAMLAtomic(path, map[string]any{"value": "two"}, 0o644); err != nil {
+		t.Fatalf("second write: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read yaml: %v", err)
+	}
+	if !strings.Contains(string(data), "two") {
+		t.Fatalf("yaml = %q, want overwritten value", string(data))
+	}
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		t.Fatalf("ReadDir() error = %v", err)
+	}
+	for _, entry := range entries {
+		name := entry.Name()
+		if strings.Contains(name, ".tmp-") {
+			t.Fatalf("temp file residue found: %q", name)
+		}
+	}
+}
+
+func TestSubprocessHelper(t *testing.T) {
+	if os.Getenv("GO_WANT_SUBPROCESS_HELPER") != "1" {
+		return
+	}
+
+	args := os.Args
+	mode := ""
+	for i := range args {
+		if args[i] == "--" && i+1 < len(args) {
+			mode = args[i+1]
+			break
+		}
+	}
+	if mode == "" {
+		os.Exit(2)
+	}
+
+	switch mode {
+	case "success":
+		_, _ = os.Stdout.WriteString(os.Getenv("SUBPROCESS_HELPER_STDOUT") + "\n")
+		_, _ = os.Stderr.WriteString(os.Getenv("SUBPROCESS_HELPER_STDERR") + "\n")
+		os.Exit(0)
+	case "fail":
+		_, _ = os.Stderr.WriteString("intentional failure\n")
+		os.Exit(3)
+	case "sleep":
+		time.Sleep(500 * time.Millisecond)
+		os.Exit(0)
+	default:
+		os.Exit(2)
+	}
+}