nandi/cosmicnim · 208eb39

⑂ 208eb39

Cover the operator path into the divide-by-zero error

resolve has two callers and only equals was tested. An operator commits
the pending division just as equals does, so `1 / 0 +` errors on the plus
— and pressing divide itself must not error, since it only sets the
pending op. Also pins the implied-operand cases, 0/0 and a negative zero
divisor, which IEEE equality catches but nothing stated.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

nandithebull committed 2026-09-20T12:08:18-07:00 Browse files

208eb39 parent: d1e3be7

modified tests/tcalculator.nim +18 -0 Viewed

@@ -45,6 +45,24 @@ suite "calculator":
45	45	check c.reason == "" # cleared along with the error
46	46	check c.press(7) == "7" # usable again
47	47
	48	+ test "an operator commits the pending divide, so it errors there too":
	49	+ # The error surfaces on the key that commits the division, which is the
	50	+ # next operator just as much as it is equals.
	51	+ var c = fresh()
	52	+ check c.press(1, IdDiv, 0, IdAdd) == "Error"
	53	+ check c.reason == "Cannot divide by zero"
	54	+
	55	+ test "pressing divide is not itself an error":
	56	+ var c = fresh()
	57	+ check c.press(1, IdDiv) == "1"
	58	+ check not c.failed
	59	+
	60	+ test "dividing by an implied zero operand is caught":
	61	+ var c = fresh()
	62	+ check c.press(0, IdDiv, IdEquals) == "Error" # 0 / 0
	63	+ c = fresh()
	64	+ check c.press(0, IdSign, 1, IdDiv, 0, IdSign, IdEquals) == "Error" # -0
	65	+
48	66	test "a result too large to represent says so, rather than showing inf":
49	67	var c = fresh()
50	68	# Each pass multiplies by ~1e18; float64 gives up a little past 1e308.

      check c.reason == ""                 # cleared along with the error
      check c.press(7) == "7"              # usable again
++  test "an operator commits the pending divide, so it errors there too":
++    # The error surfaces on the key that commits the division, which is the
++    # next operator just as much as it is equals.
++    var c = fresh()
++    check c.press(1, IdDiv, 0, IdAdd) == "Error"
++    check c.reason == "Cannot divide by zero"
++
++  test "pressing divide is not itself an error":
++    var c = fresh()
++    check c.press(1, IdDiv) == "1"
++    check not c.failed
++
++  test "dividing by an implied zero operand is caught":
++    var c = fresh()
++    check c.press(0, IdDiv, IdEquals) == "Error"   # 0 / 0
++    c = fresh()
++    check c.press(0, IdSign, 1, IdDiv, 0, IdSign, IdEquals) == "Error"  # -0
++
    test "a result too large to represent says so, rather than showing inf":
      var c = fresh()
      # Each pass multiplies by ~1e18; float64 gives up a little past 1e308.