}

func TestFileReader(t *testing.T) {
	type (
		testRead struct { // Read(cnt) == (wantStr, wantErr)
			cnt     int
			wantStr string
			wantErr error
		}
		testWriteTo struct { // WriteTo(testFile{ops}) == (wantCnt, wantErr)
			ops     fileOps
			wantCnt int64
			wantErr error
		}
		testRemaining struct { // logicalRemaining() == wantLCnt, physicalRemaining() == wantPCnt
			wantLCnt int64

	"time"
)

type testError struct{ error }

type fileOps []any // []T where T is (string | int64)

// testFile is an io.ReadWriteSeeker where the IO operations performed
// on it must match the list of operations in ops.
type testFile struct {
	ops fileOps
	pos int64
}

func (f *testFile) Read(b []byte) (int, error) {
	if len(b) == 0 {
		return 0, nil
	}
	if len(f.ops) == 0 {
		return 0, io.EOF
	}

			hdr     Header
			wantErr error
		}
		testWrite struct { // Write(str) == (wantCnt, wantErr)
			str     string
			wantCnt int
			wantErr error
		}
		testReadFrom struct { // ReadFrom(testFile{ops}) == (wantCnt, wantErr)
			ops     fileOps
			wantCnt int64
			wantErr error
		}
		testClose struct { // Close() == wantErr
			wantErr error
		}