Explicit extension operator invocations tested?

[eernstg]

Cf. dart-lang/sdk#38895, I took a look at the co19 tests on extension methods. I think they don't cover the case where an explicitly resolved extension method invocation calls an operator (example derived from this one):

extension X on bool {
  bool operator+(bool other) => this | other;
}

main() {
  print(X(false) + true);
}

I searched for strings like ) + and ) *, but did not find examples where this feature is used.

[sgrekhov]

Test uses operator "-" (unary minus). It defined here and used, for example, here. Is this desired test?

[eernstg]

Not quite: The point is that an analysis which is a little bit too fast would say that X(false) + true is an error because X(false) cannot occur as an expression. But the addition is just an instance method invocation, so even though it is different syntactically it is similar to X(false).foo(true) where foo is an extension method declared in the extension X.

And I couldn't find any test cases where explicit resolution of an extension operator is used (like X(false) + true, as opposed to the implicit ones like false + true). The example using unary minus is also implicit: -list and -list.split(1); the explicitly resolved version would be -MyFancyList(list) and -MyFancyList(list.split(1)).