Python: Fix test issues

Fixes the test failures that arose from making `ExtractedArgumentNode`
local.

For the consistency checks, we now explicitly exclude the
`ExtractedArgumentNode`s (now much more plentiful due to the
overapproximation) that don't have a corresponding `getCallArg` tuple.

For various queries/tests using `instanceof ArgumentNode`, we instead us
`isArgumentNode`, which explicitly filters out the ones for which
`isArgumentOf` doesn't hold (which, again, is the case for most of the
nodes in the overapproximation).

python/ql/consistency-queries/DataFlowConsistency.ql

@@ -26,6 +26,8 @@ private module Input implements InputSig<Location, PythonDataFlow> {
     or
     // TODO: Implement post-updates for **kwargs, see tests added in https://github.com/github/codeql/pull/14936
     exists(ArgumentPosition apos | n.argumentOf(_, apos) and apos.isDictSplat())
+    or
+    missingArgumentCallExclude(n)
   }
 
   predicate reverseReadExclude(Node n) {
@@ -134,6 +136,14 @@ private module Input implements InputSig<Location, PythonDataFlow> {
       other.getNode().getScope() = f
     )
   }
+
+  predicate missingArgumentCallExclude(ArgumentNode arg) {
+    // We overapproximate the argument nodes in order to not rely on the global `getCallArg`
+    // predicate.
+    // Because of this, we must exclude the cases where we have an approximation but no actual
+    // argument node.
+    arg = getCallArgApproximation() and not getCallArg(_, _, _, arg, _)
+  }
 }
 
 import MakeConsistency<Location, PythonDataFlow, PythonTaintTracking, Input>

python/ql/lib/utils/test/dataflow/MaximalFlowTest.qll

@@ -35,7 +35,7 @@ module MaximalFlowsConfig implements DataFlow::ConfigSig {
   predicate isSink(DataFlow::Node node) {
     exists(node.getLocation().getFile().getRelativePath()) and
     not any(CallNode c).getArg(_) = node.asCfgNode() and
-    not node instanceof DataFlow::ArgumentNode and
+    not isArgumentNode(node, _, _) and
     not node.asCfgNode().(NameNode).getId().matches("SINK%") and
     not DataFlow::localFlowStep(node, _)
   }

python/ql/lib/utils/test/dataflow/callGraphConfig.qll

@@ -9,7 +9,7 @@ module CallGraphConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node node) {
     node instanceof DataFlowPrivate::ReturnNode
     or
-    node instanceof DataFlow::ArgumentNode
+    DataFlowPrivate::isArgumentNode(node, _, _)
   }
 
   predicate isSink(DataFlow::Node node) {

python/ql/src/Classes/InitCallsSubclass/InitCallsSubclassMethod.ql

@@ -15,6 +15,7 @@
 import python
 import semmle.python.dataflow.new.DataFlow
 import semmle.python.dataflow.new.internal.DataFlowDispatch
+import semmle.python.dataflow.new.internal.DataFlowPrivate
 
 predicate initSelfCallOverridden(
   Function init, DataFlow::Node self, DataFlow::MethodCallNode call, Function target,
@@ -39,7 +40,7 @@ predicate readsFromSelf(Function method) {
     self.getParameter() = method.getArg(0) and
     DataFlow::localFlow(self, sink)
   |
-    sink instanceof DataFlow::ArgumentNode
+    isArgumentNode(sink, _, _)
     or
     sink = any(DataFlow::AttrRead a).getObject()
   )