add test for predicateExpr

Author: erik-krogh

ql/test/callgraph/Foo.qll

@@ -37,3 +37,11 @@ module Buildins {
 
   predicate regexpCapture(string s) { "foo".regexpCapture("\\w", 1) = s }
 }
+
+cached
+newtype TApiNode = MkRoot()
+
+private predicate edge(TApiNode a, TApiNode b) { a = b }
+
+cached
+int distanceFromRoot(TApiNode nd) = shortestDistances(MkRoot/0, edge/2)(_, nd, result)

ql/test/callgraph/callgraph.expected

@@ -22,3 +22,7 @@ getTarget
 | packs/src/SrcThing.qll:5:3:5:8 | PredicateCall | packs/src/SrcThing.qll:8:1:8:30 | ClasslessPredicate bar |
 dependsOn
 | packs/src/qlpack.yml:1:1:1:4 | ql-testing-src-pack | packs/lib/qlpack.yml:1:1:1:4 | ql-testing-lib-pack |
+exprPredicate
+| Foo.qll:24:22:24:31 | predicate | Foo.qll:22:3:22:32 | ClasslessPredicate myThing0 |
+| Foo.qll:26:22:26:31 | predicate | Foo.qll:20:3:20:54 | ClasslessPredicate myThing2 |
+| Foo.qll:47:65:47:70 | predicate | Foo.qll:44:9:44:56 | ClasslessPredicate edge |

ql/test/callgraph/callgraph.ql

@@ -3,3 +3,5 @@ import ql
 query AstNode getTarget(Call call) { result = call.getTarget() }
 
 query YAML::QLPack dependsOn(YAML::QLPack pack) { result = pack.getADependency() }
+
+query Predicate exprPredicate(PredicateExpr expr) { result = expr.getResolvedPredicate() }