From Voile's post below, that operation translates to this:
0 / 117 -> 0 / 89 -> 0
Actual and expected seems to be flipped on some tests.

I don't understand why no one responding to my queries / issues.

FluentCalculator::init()->dividedBy->dividedBy->times->dividedBy->zero->one->one->seven->plus->dividedBy->eight->nine()
Failed asserting that 1 is identical to 0.

Is obviously wrong. This is from the last random tests which each tests I've manually calculated myself based from the instructions, they are all wrong.

Unless I'm missing something, HINT if ever please?

6 days and i still don't get a reply.

Last random tests keep failing, i output the given and calculate it manually myself based from requirements, expected answer is wrong.

oh that's true. i forgot to add the equal numbers on my checks :| thanks

...All of the ?s in an expression will represent the same digit (0-9), and it won't be one of the other given digits in the expression.

That

You're probably misunderstanding what to do, read the kata description again:

• Given an expression, figure out the value of the rune represented by the question mark. If more than one digit works, give the lowest one. If no digit works, well, that's bad news for the professor - it means that he's got some of his runes wrong. output -1 in that case.
• Don't get what you're saying there, could you provide the input and expected answer of those tests?
• Already answered above.

I got multple issues here:

• ? can be from 0 to 9 so it is all possitive. A test case suggest the expected answer is -1
• There were no mentioned rule that multiple of 1 or 0 is not counted as an answer, but the tests suggests so; atleast 2
• Adding to my first bullet point, for test case "assertEquals(-1, solve_expression('19--45=5?'));" how is -1 an answer? It would be "=5-1" ?