Process a union or intersection type of all strings as a string - #675

1. This test isn't really related to string.toUpperCase, but to general array string detection, so it should be be placed before string constrained generic foreach (%p) and be renamed
2. There's no need for test.each, since it's not the main reason for this test
3. The code inside template is indented with 2 spaces instead of 4
4. Variables shouldn't begin with underscore, typescript uses it for it's unused diagnostics
5. I don't see much reason to over-complicate test code with inference logic, something like this would be enough to prove test's point:

const union: "foo" | "bar" = "foo";
return union.length;

1. I was mainly concerned with string.* being transpiled correctly, hence I thought it made sense to have it around here. I'll move it :)
2. I guess you are right.
3. Woopsie 👍
4. Gotcha - fixed in the next push.
5. Your proposal doesn't cover this. union here is just a string literal which already supports .length. Enforcing union to be a string type triggers the type guard which appears to compare the string to a union of each or-condition. Inside the if-block, union is now inferred as an actual union of strings.

   const union: string = "foo";
   
   if (union === "foo" || union === "bar") {
       return union.length;
   }
   
   return 0;
   

   ^ does the trick, though!

Oh, looks like TS ignores type annotation in this case and only something like const union = "foo" as "foo" | "bar"; works

.each with a single case can be removed completely and be inlined to code.

Done :)