PS: Add test.

Author: MathiasVP

powershell/ql/test/library-tests/dataflow/params/test.ps1

@@ -3,4 +3,37 @@ function Foo($a) {
 }
 
 $x = Source "1"
-Foo $x
+Foo $x
+
+function ThreeArgs($x, $y, $z) {
+    Sink $x # $ MISSING: hasValueFlow=x
+    Sink $y # $ MISSING: hasValueFlow=y
+    Sink $z # $ MISSING: hasValueFlow=z
+}
+
+$first = Source "x"
+$second = Source "y"
+$third = Source "z"
+
+ThreeArgs $first $second $third
+ThreeArgs $second -x $first $third
+ThreeArgs -x $first $second $third
+ThreeArgs $first -y $second $third
+ThreeArgs -y $second $first $third
+ThreeArgs $second -x $first -z $third
+ThreeArgs -x $first $second -z $third
+ThreeArgs $first -y $second -z $third
+ThreeArgs -y $second $first -z $third
+ThreeArgs $second -x $first -z $third
+ThreeArgs -x $first -z $third $second
+ThreeArgs $first -y $second -z $third
+ThreeArgs -y $second -z $third $first
+ThreeArgs $second -z $third -x $first
+ThreeArgs -x $first -z $third $second
+ThreeArgs $first -z $third -y $second
+ThreeArgs -y $second -z $third $first
+ThreeArgs -z $third -y $second $first
+ThreeArgs -z $third $second -x $first
+ThreeArgs -z $third -x $first $second
+ThreeArgs -z $third $first -y $second
+ThreeArgs -z $third -y $second $first