fix(migrate): validate migration directory before provider creation

migrate/migrate.go

@@ -15,6 +15,7 @@ import (
 
 // New returns a provider for SQL files in dir and optional provider-local Go
 // migrations. Pass "." for files at the embedded root and a nonnil logger.
+// The selected directory must exist, including when using only Go migrations.
 // Construction does not connect to db; the caller owns and closes db.
 //
 // PostgreSQL uses Goose's session advisory locker with its default lock ID and
@@ -36,6 +37,13 @@ func New(db *sql.DB, dialect goose.Dialect, files embed.FS, dir string, logger *
 	if err != nil {
 		return nil, fmt.Errorf("migrate: directory %q: %w", dir, err)
 	}
+	info, err := fs.Stat(root, ".")
+	if err != nil {
+		return nil, fmt.Errorf("migrate: directory %q: %w", dir, err)
+	}
+	if !info.IsDir() {
+		return nil, fmt.Errorf("migrate: directory %q: not a directory", dir)
+	}
 	opts := []goose.ProviderOption{
 		goose.WithDisableGlobalRegistry(true),
 		goose.WithGoMigrations(migrations...),

migrate/migrate_test.go

@@ -8,6 +8,7 @@ import (
 	"embed"
 	"errors"
 	"io"
+	"io/fs"
 	"log/slog"
 	"os"
 	"path/filepath"
@@ -414,3 +415,43 @@ func TestConstructor(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestConstructorDirectory(t *testing.T) {
+	db, err := sql.Open("sqlite", ":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Directory validation and Go-only construction must remain offline.
+	if err := db.Close(); err != nil {
+		t.Fatal(err)
+	}
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	for _, test := range []struct {
+		dir     string
+		wantErr string
+	}{
+		{dir: "missing", wantErr: "directory"},
+		{dir: "testdata/migrations/00007_events.sql", wantErr: "not a directory"},
+		{dir: "."},
+		{dir: "testdata"},
+	} {
+		t.Run(test.dir, func(t *testing.T) {
+			p, err := migrate.New(db, goose.DialectSQLite3, fixtures, test.dir, logger, goose.NewGoMigration(10, nil, nil))
+			if test.wantErr != "" {
+				if err == nil || p != nil || !strings.Contains(err.Error(), test.wantErr) || !strings.Contains(err.Error(), test.dir) {
+					t.Fatalf("New = %v, %v; want directory error containing %q and %q", p, err, test.wantErr, test.dir)
+				}
+				if test.dir == "missing" && !errors.Is(err, fs.ErrNotExist) {
+					t.Fatalf("New error = %v; want fs.ErrNotExist", err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if sources := p.ListSources(); len(sources) != 1 || sources[0].Version != 10 {
+				t.Fatalf("ListSources = %v; want Go migration 10 only", sources)
+			}
+		})
+	}
+}