Fixed.

Still an exact duplicate a bazillion times over, or katas which are themselves duplicates of many other isPrime katas :

https://www.codewars.com/kata/search/?q=prime&beta=false

Is this still an issue, because if I fork them, there are solutions which pass the tests.

Random test cases added.

Not an issue. Your code is wrong.

Nice work on adding the randoms, those kinds of tests are not at all easy for beginners to do.

I am not sure that random tests are so critical in very low level kata, especially bug fix ones. Anyone who could hard code this is likely to not be learning from the bug-fixing anyway.

That being said, a couple of random tokens were added.

You need to put this function on the String prototype

I am not sure I see the value in having very specific methods necessary with no clue as to what they are. A beginner searches for a list, finds something like forEach, works perfectly fine, massively shortens the code - and it is rejected? It also looks like map was initially rejected and later added. This just seemst to be a way to frustrate beginners.

My code doesn't pass the tests here but it works with MinGW compiler. Why?

int i,n; char *st;
n = strlen(s);
strcpy(st,s);
for(i = 0; i < n; i++)
{
if(*st <= 122 && *st >= 97)
*st -= 32;
else if(*st <= 88 && *st >= 65)
*st += 32;
st++;
}
if(*st <= 122 && *st >= 97)
*st -= 32;
else if(*st <= 88 && *st >= 65)
*st += 32;
return st-i;

There are a bunch of translations, please specify the language even if there is only one at the time.

Just added to JS.

for some reason the test "(" first was wrong but after compiling again it turned right