t.Fatalf("Flush() = %v, want %v", err, ErrWriteAfterClose)
		}
		if err := tw.Close(); err != nil {
			t.Fatalf("Close() = %v, want nil", err)
		}
	})

	t.Run("PrematureFlush", func(t *testing.T) {
		tw := NewWriter(new(bytes.Buffer))
		hdr := &Header{Name: "small.txt", Size: 5}
		if err := tw.WriteHeader(hdr); err != nil {
			t.Fatalf("WriteHeader() = %v, want nil", err)
		}