felix math test cases from muhajir

gistfile1.txt

balance: cumulative running total of (deposits - expenses) (what the bank knows about my account)

goal: a sub-account devoted to a purpose, to be funded periodically in order to reach a predefined amount by a predefined date

allowance = money you have available to spend once  money has been allocated to your goals from your balance.

savings = sum(goals) or  aggregate amount of money allocated to all your goals
and
allowance = balance - savings

savings should go up when money is allocated to a goal. savings refers to your savings within the app

test case 1: Creating an expense should subtract the amount from balance.
PRE: Balance = 100
expense = -10

post
balance = 90

test case 2: Creating an expense where the amount is less than or equal to the allowance should subtract the amount from the allowance.
pre:
balance = 100
allowance = 100
expense = -10

post 
balance = 90
allowance = 90


test case 3A: Creating an expense where the amount is greater than the allowance should make allowance = 0 (allowance should never be negative). 
pre:
balance = 100
allowance = 100
expense = -110

post 
balance = -10
allowance = 0


test case 3B: Creating an expense where the amount is greater than the allowance should add the negative difference of (amount + allowance) to the user’s total saved (adding the negative difference will decrease the total amount).

pre:
balance = 100
allowance = 100
goal 1 = 100/200 (current total/ goal target)
goal 2 = 200/300
saved = 300
expense = -110

post 
balance = -10
saved = 300 +(-110+100) (saved = saved +( expense+allowance))
= 290
deallocation amount = -10

allowance = 0
“expenses will deplete savings before deallocating goals"

test case 3C: Creating an expense where the amount is greater than the allowance should deallocate the negative difference of (amount + allowance) from the user’s goals, where each goal is deallocated an amount proportional to it’s ratio to the total saved amount of the user.

pre:
balance = 100
allowance = 100
goal 1 = 100/200
goal 2 = 200/300
saved = 300
expense = -110

post 
balance = -10
saved = 300 +(-110+100) (saved = saved +( expense+allowance))
= 190
goal 1 = 96.67/200 ( 100 - (1/3)*10) // deallocated in proportion to previous goal amount / previous savings
goal 2 = 193.33/300 (200 - (2/3)*10)
Note = rounding to the nearest cent handling: first goal processed gets the extra money to make the whole cent, all others are less that the float amount.
allowance = 0
“expenses will deplete savings by reducing goals in proportion to their ratio of goal-balance/savings before deallocating goals"

test case 4: Goals should only be deallocated from if their current amount is greater than 0. (edited) 
pre:
balance = 100
allowance = 100
goal 1 = 0/200
goal 2 = 200/300
saved = 200
expense = -110

post 
balance = -10
saved = 200 +(-110+100) (saved = saved +( expense+allowance))
= 190
goal 1 = 0/200 
goal 2 = 190/300 
allowance = 0

testing periodic function