Given ledger:
  2020-03-06 Buy
    Expenses  $10.00
    Cash

Execute (set state):
  2
  call ledger#transaction_post_state_set(line('.'), '*')

Expect ledger:
  2020-03-06 Buy
    * Expenses  $10.00
    Cash

Execute (clear state):
  2
  call ledger#transaction_post_state_set(line('.'), '*')
  call ledger#transaction_post_state_set(line('.'), '')

Expect ledger:
  2020-03-06 Buy
    Expenses  $10.00
    Cash

Execute (clear already clear state):
  2
  call ledger#transaction_post_state_set(line('.'), '')

Expect ledger:
  2020-03-06 Buy
    Expenses  $10.00
    Cash

Execute (toggle state):
  2
  call ledger#transaction_post_state_toggle(line('.'), '!* ')

Expect ledger:
  2020-03-06 Buy
    ! Expenses  $10.00
    Cash

Execute (toggle state x2):
  2
  call ledger#transaction_post_state_toggle(line('.'), '!* ')
  call ledger#transaction_post_state_toggle(line('.'), '!* ')

Expect ledger:
  2020-03-06 Buy
    * Expenses  $10.00
    Cash

Execute (toggle state x3):
  2
  call ledger#transaction_post_state_toggle(line('.'), '!* ')
  call ledger#transaction_post_state_toggle(line('.'), '!* ')
  call ledger#transaction_post_state_toggle(line('.'), '!* ')

Expect ledger:
  2020-03-06 Buy
    Expenses  $10.00
    Cash

Execute (fallback to posting):
  call ledger#transaction_post_state_toggle(line('.'), '!* ')

Expect ledger:
  2020-03-06 ! Buy
    Expenses  $10.00
    Cash

Execute (fallback to posting, clear):
  call ledger#transaction_post_state_set(line('.'), ' ')

Expect ledger:
  2020-03-06 Buy
    Expenses  $10.00
    Cash