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## The keypad logic is pure Nim, so it can be driven without a window:
## press keys straight into onPress and read back what the display would say.

import std/unittest
import ../examples/calculator

proc press(c: var Calc; ids: varargs[int32]): string =
  for id in ids:
    onPress(addr c, id)
  c.display

proc fresh(): Calc = newCalc()

suite "calculator":
  test "digits accumulate into one entry":
    var c = fresh()
    check c.press(1, 2, 3) == "123"

  test "no leading zeros":
    var c = fresh()
    check c.press(0, 0, 5) == "5"

  test "addition":
    var c = fresh()
    check c.press(2, IdAdd, 3, IdEquals) == "5"

  test "chaining resolves the pending op as you go":
    var c = fresh()
    check c.press(2, IdAdd, 3, IdMul, 4) == "4"   # 2+3 folded, 4 being typed
    check c.press(IdEquals) == "20"               # then (5)*4

  test "subtraction and division":
    var c = fresh()
    check c.press(9, IdSub, 4, IdEquals) == "5"
    c = fresh()
    check c.press(8, IdDiv, 2, IdEquals) == "4"

  test "division by zero errors, and only C recovers":
    var c = fresh()
    check c.press(1, IdDiv, 0, IdEquals) == "Error"
    check c.press(5) == "Error"          # other keys are ignored
    check c.press(IdClear) == "0"
    check c.press(7) == "7"              # usable again

  test "decimals":
    var c = fresh()
    check c.press(1, IdDot, 5, IdAdd, 2, IdDot, 2, 5, IdEquals) == "3.75"

  test "a bare dot starts at zero":
    var c = fresh()
    check c.press(IdDot, 5) == "0.5"

  test "one dot per number":
    var c = fresh()
    check c.press(1, IdDot, 2, IdDot, 3) == "1.23"

  test "sign flips the entry, then the result":
    var c = fresh()
    check c.press(4, IdSign) == "-4"
    check c.press(IdSign) == "4"
    c = fresh()
    check c.press(2, IdAdd, 3, IdEquals, IdSign) == "-5"

  test "percent":
    var c = fresh()
    check c.press(5, 0, IdPercent) == "0.5"

  test "integers do not grow a decimal point":
    var c = fresh()
    check c.press(6, IdDiv, 3, IdEquals) == "2"

  test "a new number replaces the result, not appends to it":
    var c = fresh()
    check c.press(2, IdAdd, 3, IdEquals) == "5"
    check c.press(7) == "7"