Add test for goto targeting stacked label

Author: owen-mc

go/ql/test/library-tests/semmle/go/controlflow/GotoTarget/GotoTarget.expected

@@ -0,0 +1,19 @@
+import go
+import utils.test.InlineExpectationsTest
+
+module GotoTargetTest implements TestSig {
+  string getARelevantTag() { result = "gotoTarget" }
+
+  predicate hasActualResult(Location location, string element, string tag, string value) {
+    exists(GotoStmt jump, LabeledStmt target |
+      jump.getLocation() = location and
+      jump.getLabel() = target.getLabel() and
+      target.getStmt().getFirstControlFlowNode() = jump.getFirstControlFlowNode().getASuccessor+() and
+      element = jump.toString() and
+      tag = "gotoTarget" and
+      value = target.getLabel()
+    )
+  }
+}
+
+import MakeTest<GotoTargetTest>

go/ql/test/library-tests/semmle/go/controlflow/GotoTarget/GotoTarget.ql

@@ -0,0 +1,25 @@
+package main
+
+func gotoStackedLabelTarget(flag bool) {
+outer:
+inner:
+	{
+		if flag {
+			goto back // $ gotoTarget=back
+		}
+		goto done // $ gotoTarget=done
+
+	back:
+		goto inner // $ MISSING: gotoTarget=inner
+	done:
+		flag = false
+	}
+	goto outer // $ gotoTarget=outer
+}
+
+func gotoDirectStackedLabelTarget() {
+	goto outer // $ gotoTarget=outer
+outer:
+inner:
+	goto inner // $ gotoTarget=inner
+}