Python: test phi definitions at module exit

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: yoff

python/ql/test/library-tests/dataflow-new-ssa/SsaTest.ql

@@ -10,6 +10,8 @@
  *     of `<var>` reaches the read.
  *   - `phi=<var>`: there is an SSA phi definition of `<var>` whose BB
  *     starts on this line.
+ *   - `exit-use=<var>`: a phi definition of `<var>` reaches the synthetic
+ *     normal-exit read through the ESSA adapter.
  */
 
 import python
@@ -19,7 +21,7 @@ import semmle.python.controlflow.internal.Cfg as Cfg
 import utils.test.InlineExpectationsTest
 
 module SsaTest implements TestSig {
-  string getARelevantTag() { result = ["def", "use", "phi"] }
+  string getARelevantTag() { result = ["def", "use", "phi", "exit-use"] }
 
   predicate hasActualResult(Location location, string element, string tag, string value) {
     // A `def=<id>` fires when an SSA WriteDefinition is at a CFG node
@@ -53,6 +55,18 @@ module SsaTest implements TestSig {
       element = bb.toString() and
       value = phi.getSourceVariable().(SsaImpl::SsaSourceVariable).getVariable().getId()
     )
+    or
+    exists(SsaImpl::PhiFunction phi, SsaImpl::EssaVariable variable, CfgImpl::BasicBlock bb,
+      Cfg::ControlFlowNode exit |
+      variable = phi and
+      phi.definesAt(_, bb, _) and
+      variable.getAUse() = exit and
+      exit.isNormalExit() and
+      tag = "exit-use" and
+      location = bb.getNode(0).getLocation() and
+      element = bb.toString() and
+      value = phi.getSourceVariable().(SsaImpl::SsaSourceVariable).getVariable().getId()
+    )
   }
 }
 

python/ql/test/library-tests/dataflow-new-ssa/test.py

@@ -16,6 +16,12 @@
 # on its `def` line.
 
 
+if object():  # $ phi=conditional_factory MISSING: exit-use=conditional_factory
+    from primary_backend import Factory as conditional_factory  # $ def=conditional_factory
+else:
+    from fallback_backend import Factory as conditional_factory  # $ def=conditional_factory
+
+
 def basic_param(x):  # $ def=basic_param def=x
     return x  # $ use=x
 
@@ -44,5 +50,3 @@ def if_else_phi(cond):  # $ def=if_else_phi def=cond
 # read resolves to no SSA def, hence there is no `use=` here.
 def use_global():  # $ def=use_global
     return some_undefined
-
-