assertSignature: added test for alternative syntax

tests/fn.assertSignature.allRequired.phpt

@@ -10,6 +10,7 @@ $f1 = function(T1 $t1, T2 $t2): T3 {return new T3;};
 
 // Positive scenario
 assertSignature($f1, params(T1::class, T2::class), T3::class);
+assertSignature($f1, [T1::class, T2::class], T3::class); // alternative syntax
 
 // Optional by accident: parameter
 Assert::exception(function () use ($f1) {