test: cover sandbox fs Windows path handling

pkg/tools/fs/filesystem_windows_path_test.go

@@ -0,0 +1,57 @@
+package fstools
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestSandboxFsReadDirAcceptsOSSpecificRelativePaths(t *testing.T) {
+	workspace := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(workspace, "aaa", "bbb", "ccc"), 0o755); err != nil {
+		t.Fatalf("create nested directory: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(workspace, "aaa", "bbb", "file.txt"), []byte("hello"), 0o600); err != nil {
+		t.Fatalf("create nested file: %v", err)
+	}
+
+	fsys := &sandboxFs{workspace: workspace}
+	entries, err := fsys.ReadDir(filepath.Join("aaa", "bbb"))
+	if err != nil {
+		t.Fatalf("ReadDir with OS-specific relative path returned error: %v", err)
+	}
+
+	seen := map[string]bool{}
+	for _, entry := range entries {
+		seen[entry.Name()] = true
+	}
+	if !seen["ccc"] || !seen["file.txt"] {
+		t.Fatalf("ReadDir entries = %v, want ccc and file.txt", seen)
+	}
+}
+
+func TestSandboxFsOpenAcceptsOSSpecificRelativePaths(t *testing.T) {
+	workspace := t.TempDir()
+	if err := os.MkdirAll(filepath.Join(workspace, "aaa", "bbb"), 0o755); err != nil {
+		t.Fatalf("create nested directory: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(workspace, "aaa", "bbb", "file.txt"), []byte("hello"), 0o600); err != nil {
+		t.Fatalf("create nested file: %v", err)
+	}
+
+	fsys := &sandboxFs{workspace: workspace}
+	file, err := fsys.Open(filepath.Join("aaa", "bbb", "file.txt"))
+	if err != nil {
+		t.Fatalf("Open with OS-specific relative path returned error: %v", err)
+	}
+	defer file.Close()
+
+	data, err := io.ReadAll(file)
+	if err != nil {
+		t.Fatalf("read opened file: %v", err)
+	}
+	if string(data) != "hello" {
+		t.Fatalf("file content = %q, want %q", string(data), "hello")
+	}
+}