({ label, newVarLabel, allowedVariableNodes }: NewVariableProps):
   VariableNode =>
   (allowedVariableNodes === AllowedVariableNodes.identifier && newVarLabel)
     // Create a new variable (reassignment)
     ? createParameterApplication(label,
       { kind: "identifier", args: { label: newVarLabel } })
     : { // Unassign variable (will not create a new variable name)
       kind: "parameter_declaration",
       args: { label, default_value: NOTHING_SELECTED }
     };

describe("mergeParameterApplications()", () => {
  const bodyVariables: ParameterApplication[] = [
    coordinateVar("parent1"),
    coordinateVar("parent2"),
  ];

  it("doesn't overwrite bodyVariables", () => {
    const varData = fakeVariableNameSet("parent1");
    const result = mergeParameterApplications(varData, bodyVariables);
    expect(result).toEqual(bodyVariables);
  });

  it("adds new bodyVariables", () => {
    // "parent2" will not be added: already exists
    const varData = fakeVariableNameSet("parent2");

    // "parent3" will not be added: already defined
    const notAdded = "parent3";
    varData[notAdded] = fakeVariableNameSet(notAdded)[notAdded];

    // "parent4" will be added to the existing bodyVariables
    const label = "parent4";
    const add = fakeVariableNameSet(label)[label];
    const addedNewDecl: ParameterDeclaration = {
      kind: "parameter_declaration", args: {
        label, default_value: COORDINATE
      }
    };
    add && (add.celeryNode = addedNewDecl);
    varData[label] = add;
    const expected = cloneDeep(bodyVariables);
    expected.push({
      kind: "parameter_application", args: {
        label, data_value: COORDINATE
      }
    });

    const result = mergeParameterApplications(varData, bodyVariables);
    expect(result).toEqual(expected);
  });
});

 it("returns parameter applications", () => {
   const result = variableList({
     parent1: {
       celeryNode: {
         kind: "parameter_declaration", args: {
           label: "parent1", default_value: COORDINATE
         }
       },
       dropdown: { label: "Parent1", value: "parent1" },
       vector: undefined,
     },
     parent2: {
       celeryNode: coordinateVar("parent2"),
       dropdown: { label: "Parent2", value: "parent2" },
       vector: COORDINATE.args,
     }
   });
   expect(result).toEqual([{
     kind: "parameter_application",
     args: { label: "parent1", data_value: COORDINATE }
   }]);
 });