Handle externally defined, unused variables

src/main/java/com/schibsted/spt/data/jslt/impl/Scope.java

@@ -26,12 +26,17 @@ public static Scope getRoot(int stackFrameSize) {
     return new Scope(stackFrameSize);
   }
 
+  /**
+   * Creates an initialized scope with values for variables supplied
+   * by client code into the JSLT expression.
+   */
   public static Scope makeScope(Map<String, JsonNode> variables,
                                 int stackFrameSize,
                                 Map<String, Integer> parameterSlots) {
     Scope scope = new Scope(stackFrameSize);
     for (String variable : variables.keySet())
-      scope.setValue(parameterSlots.get(variable), variables.get(variable));
+      if (parameterSlots.containsKey(variable)) // check that variable exists
+        scope.setValue(parameterSlots.get(variable), variables.get(variable));
     return scope;
   }
 

src/test/resources/function-declaration-tests.yaml

@@ -183,6 +183,17 @@ tests:
      m:foo()
    output: 22
 
+  # we're testing what happens when there is an external variable
+  # (a parameter) that's not actually referred to
+  -
+   input: {}
+   query: >
+     import "module-as-function-with-global.jslt" as m
+     m("variable is")
+   output: "\"variable is global\""
+   variables:
+     thevar: itsvalue # not actually referred to
+
   -
    input: {}
    query: >