PS: Add CFG test skeleton.

Author: MathiasVP

powershell/ql/lib/semmle/code/powershell/controlflow/ControlFlowGraph.qll

@@ -16,10 +16,7 @@ private import internal.Scope
  * Note that module declarations are not themselves CFG scopes, as they are part of
  * the CFG of the enclosing top-level or callable.
  */
-class CfgScope extends Scope instanceof CfgImpl::CfgScopeImpl {
-  /** Gets the CFG scope that this scope is nested under, if any. */
-  final CfgScope getOuterCfgScope() { none() }
-}
+class CfgScope extends Scope instanceof CfgImpl::CfgScope { }
 
 /**
  * A control flow node.

powershell/ql/lib/semmle/code/powershell/controlflow/internal/ControlFlowGraphImpl.qll

@@ -28,10 +28,10 @@ private module CfgInput implements CfgShared::InputSig<Location> {
 
   CfgScope getCfgScope(Ast n) { result = Impl::getCfgScope(n) }
 
-  predicate scopeFirst(CfgScope scope, Ast first) { scope.(Impl::CfgScopeImpl).entry(first) }
+  predicate scopeFirst(CfgScope scope, Ast first) { scope.(Impl::CfgScope).entry(first) }
 
   predicate scopeLast(CfgScope scope, Ast last, Completion c) {
-    scope.(Impl::CfgScopeImpl).exit(last, c)
+    scope.(Impl::CfgScope).exit(last, c)
   }
 
   class SplitKindBase = Splitting::TSplitKind;
@@ -56,32 +56,32 @@ private module CfgInput implements CfgShared::InputSig<Location> {
   }
 }
 
+private import CfgInput
 import CfgShared::Make<Location, CfgInput>
 
-abstract class CfgScopeImpl extends Ast {
-  abstract predicate entry(Ast first);
+class CfgScope extends Scope {
+  predicate entry(Ast first) { first(this, first) }
 
-  abstract predicate exit(Ast last, Completion c);
+  predicate exit(Ast last, Completion c) { last(this, last, c) }
 }
 
 /** Holds if `first` is first executed when entering `scope`. */
 pragma[nomagic]
-predicate succEntry(CfgScopeImpl scope, Ast first) { scope.entry(first) }
+predicate succEntry(CfgScope scope, Ast first) { scope.entry(first) }
 
 /** Holds if `last` with completion `c` can exit `scope`. */
 pragma[nomagic]
-predicate succExit(CfgScopeImpl scope, Ast last, Completion c) { scope.exit(last, c) }
+predicate succExit(CfgScope scope, Ast last, Completion c) { scope.exit(last, c) }
 
 /** Defines the CFG by dispatch on the various AST types. */
 module Trees {
   // TODO
 }
 
+private import Scope
+
 cached
-private CfgScope getCfgScopeImpl(Ast n) {
-  // TODO
-  none()
-}
+private CfgScope getCfgScopeImpl(Ast n) { result = scopeOf(n) }
 
 /** Gets the CFG scope of node `n`. */
 pragma[inline]

powershell/ql/lib/semmle/code/powershell/controlflow/internal/Scope.qll

@@ -1,19 +1,20 @@
 private import powershell
 private import ControlFlowGraphImpl
 
-class TScopeType = @function_definition; // TODO: top-level definitions (including a single top-level scope)
-
-abstract class ScopeImpl extends Ast, TScopeType {
-  final Scope getOuterScopeImpl() {
-    none() // TODO
-  }
+/** Gets the enclosing scope of `n`. */
+Scope scopeOf(Ast n) {
+  exists(Ast m | m = n.getParent() |
+    m = result
+    or
+    not m instanceof Scope and result = scopeOf(m)
+  )
 }
 
 /**
  * A variable scope. This is either a top-level (file), a module, a class,
  * or a callable.
  */
-class Scope extends Ast instanceof ScopeImpl {
+class Scope extends Ast, @script_block {
   /** Gets the outer scope, if any. */
-  Scope getOuterScope() { result = super.getOuterScopeImpl() }
+  Scope getOuterScope() { result = scopeOf(this) }
 }

powershell/ql/lib/semmle/code/powershell/controlflow/internal/Splitting.qll

@@ -5,8 +5,8 @@
 private import powershell
 private import Completion
 private import ControlFlowGraphImpl
-private import SuccessorTypes
-private import semmle.code.powershell.controlflow.ControlFlowGraph
+private import Cfg::SuccessorTypes
+private import semmle.code.powershell.controlflow.ControlFlowGraph as Cfg
 
 cached
 private module Cached {
@@ -63,15 +63,15 @@ private module ConditionalCompletionSplitting {
       none() // TODO
     }
 
-    override predicate hasEntryScope(CfgScope scope, Ast succ) { none() }
+    override predicate hasEntryScope(Cfg::CfgScope scope, Ast succ) { none() }
 
     override predicate hasExit(Ast pred, Ast succ, Completion c) {
       this.appliesTo(pred) and
       succ(pred, succ, c) and
       if c instanceof ConditionalCompletion then completion = c else any()
     }
 
-    override predicate hasExitScope(CfgScope scope, Ast last, Completion c) {
+    override predicate hasExitScope(Cfg::CfgScope scope, Ast last, Completion c) {
       this.appliesTo(last) and
       succExit(scope, last, c) and
       if c instanceof ConditionalCompletion then completion = c else any()

powershell/ql/test/library-tests/controlflow/graph/Cfg.expected

@@ -0,0 +1,11 @@
+/**
+ * @kind graph
+ */
+
+import semmle.code.powershell.Cfg
+
+class TestRelevantNode extends CfgNode {
+  string getOrderDisambiguation() { result = "" }
+}
+
+import semmle.code.powershell.controlflow.internal.ControlFlowGraphImpl::TestOutput<TestRelevantNode>

powershell/ql/test/library-tests/controlflow/graph/Cfg.ql

@@ -0,0 +1,3 @@
+$a = 1
+$b = 2
+$c = $a + $b