# Javascript Calculator Project - Issues with the test cases

I have found some of the test cases used for the calculator project (https://www.freecodecamp.org/learn/front-end-libraries/front-end-libraries-projects/build-a-javascript-calculator) to be contradictory.

I am specifically talking about test case #9

``````9. In any order, I should be able to add, subtract, multiply and divide a chain of numbers of any length, and when I hit "=", the correct result should be shown in the element with the id of "display"
``````

and test case #11

`````` If 2 or more operators are entered consecutively, the operation performed should be the last operator entered (excluding the negative (-) sign.
``````

The test script for #13

``````5 * + - 5 = 10
``````

I have written my project using equation notation - in that values are calculated cumulatively as they are entered, and so produces a result for #13 of -25.

I have checked, my calculators logic against Googles calculator which appears to use a similar approach.

Don’t mean for this post to sound negative, just something I wanted to highlight as I have spent a considerable amount of time up to this point getting a calculator to work (and it does work as it should - in line with other calculators I’ve looked at) - just not in line with this one test.

Shouldn’t it be zero? `5 + (-5) = 0`

How are you getting -25 if you are skipping the multiplication and doing addition instead?

I also do not see that example in the test, I see these.

``````'The sequence "5 * - 5" = should produce an output of "-25" '
'The sequence "5 * - + 5" = should produce an output of "10"'
'The sequence "5 + + 5" = should produce an output of "10" '
``````

That is my test case,

So may not of made myself clear in the first post:

The test case doesn’t make sense mathematically `5 * - + 5 = 25`

Mathematical rule is subtracting a positive is the same as adding a negative.

From Symbolab:

So although I understand the test case wants to ignore the middle subtraction symbol but surely it would be better to have a test case that checks that you haven’t entered a formula in that format. Rather than when you enter that format, it equals a number which isn’t mathematically correct.

IMO should check if

``````input: 5 * - + 5
Output: 5*5 = 25  (same as saying: 5 * (+5))

``````

But that is the requirement. Skip the operation if followed by another operation unless the operator is minus, in which case, make the number that follows a negative number.

If you put what you say into `eval`, then yes you would get -25

``````eval('5 * - + 5')
-25
``````

But that is not what the requirement says to do.

Edit:
If you want you can open an issue on one of the repos