C#: add isParameterless predicate to Constructor class

Author: Jami Cogswell

csharp/ql/lib/semmle/code/csharp/Callable.qll

@@ -358,6 +358,9 @@ class Constructor extends DotNet::Constructor, Callable, Member, Attributable, @
     if this.isStatic() then result = this.getParameter(i) else result = this.getParameter(i - 1)
   }
 
+  /** Holds if this is a constructor without parameters. */
+  predicate isParameterless() { this.getNumberOfParameters() = 0 }
+
   override string getUndecoratedName() { result = ".ctor" }
 }
 

csharp/ql/src/Telemetry/ExternalApi.qll

@@ -24,17 +24,13 @@ class TestLibrary extends RefType {
   }
 }
 
-/** Holds if the given callable is a constructor without parameters. */
-private predicate isParameterlessConstructor(DotNet::Callable c) {
-  c instanceof Constructor and c.getNumberOfParameters() = 0
-}
-
 /** Holds if the given callable is part of a common testing library or framework. */
 private predicate isTestLibrary(DotNet::Callable c) { c.getDeclaringType() instanceof TestLibrary }
 
 /** Holds if the given callable is not worth supporting. */
 private predicate isUninteresting(DotNet::Callable c) {
-  isTestLibrary(c) or isParameterlessConstructor(c)
+  isTestLibrary(c) or
+  c.(Constructor).isParameterless()
 }
 
 /**