Add inline tests for API Graph subclassing

Author: hmac

ruby/ql/lib/codeql/ruby/ApiGraphs.qll

@@ -160,7 +160,7 @@ module API {
     /**
      * Gets a path of the given `length` from the root to this node.
      */
-    private string getAPath(int length) {
+    string getAPath(int length) {
       this instanceof Impl::MkRoot and
       length = 0 and
       result = ""
@@ -174,8 +174,7 @@ module API {
           // avoid producing strings longer than 1MB
           result.length() < 1000 * 1000
         )
-      ) and
-      length in [1 .. Impl::distanceFromRoot(this)]
+      )
     }
 
     /** Gets the shortest distance from the root to this node in the API graph. */

ruby/ql/test/library-tests/dataflow/api-graphs/test1.rb

@@ -29,3 +29,23 @@ module Inner
 end
 
 Outer::Inner.foo #$ use=getMember("Outer").getMember("Inner").getReturn("foo")
+
+module M1
+    class C1
+    end
+end
+
+class C2 < M1::C1 #$ use=getMember("M1").getMember("C1")
+end
+
+module M2
+    class C3 < M1::C1 #$ use=getMember("M1").getMember("C1")
+    end
+    
+    class C4 < C2 #$ use=getMember("C2")
+    end
+end
+
+C2 #$ use=getMember("C2") use=getMember("M1").getMember("C1").getASubclass()
+M2::C3 #$ use=getMember("M2").getMember("C3") use=getMember("M1").getMember("C1").getASubclass()
+M2::C4 #$ use=getMember("M2").getMember("C4") use=getMember("C2").getASubclass() use=getMember("M1").getMember("C1").getASubclass().getASubclass()

ruby/ql/test/library-tests/dataflow/api-graphs/use.ql

@@ -30,6 +30,16 @@ class ApiUseTest extends InlineExpectationsTest {
       element = n.toString()
     )
   }
+
+  // We also permit optional annotations for any other path on the line.
+  // This is used to test subclass paths, which typically have a shorter canonical path.
+  override predicate hasOptionalResult(Location location, string element, string tag, string value) {
+    exists(API::Node a, DataFlow::Node n | relevantNode(a, n, location) |
+      tag = "use" and
+      element = n.toString() and
+      value = a.getAPath(_)
+    )
+  }
 }
 
 private int size(AstNode n) { not n instanceof StmtSequence and result = count(n.getAChild*()) }