2018/01/01 * Opening Balance
    Assets:Checking                             $1000.00
    Equity:Opening Balances                    -$1000.00

2018/01/01 * Budget
    Assets:Budget:Rent                           $100.00
    Assets:Budget:Emergency                      $200.00
    Assets:Checking                             -$300.00

2018/01/01 * Budget
    Assets:Budget:Rent                                 $0
    Assets:Budget:Emergency                     = $400.00
    Assets:Bank                                  -$500.00

$ hledger -f- check

#test bal Assets -> 1
#__ERROR__
#While parsing file "$FILE", line 13:
#While balancing transaction from "$FILE", lines 10-13:
#> 2018/01/01 * Budget
#>     Assets:Budget:Rent                                 $0
#>     Assets:Budget:Emergency                     = $400.00
#>     Assets:Bank                                  -$500.00
#Unbalanced remainder is:
#            $-300.00
#Amount to balance against:
#             $200.00
#Error: Transaction does not balance
#end test
#