unit-testing google-apps-script closures search-tree

Search tree node via closure in Google Apps Script

General problem I'm trying to solve

I'm trying to implement a search tree in Google Apps Script, sorted by pkgName attribute, with the end purpose of comparing imported metadata on a software project against a Sheet containing similar data.

To keep the namespace of the constructor function from being polluted with "private" properties, I used closures.

Implementation

The implementation I have thus far is thus:

SheetDataNode.gs

/**
 *  Constructor for a SheetDataNode. Takes one, three, or four arguments.
 *  @param { { package : string, files : { complexity : number, name : string, testingStatus : string }[], rowNumber : number } | string } line data or package name
 *  @param { string } filename : the files contained in package
 *  @param { number } complexity : the total number of branches in the file 
 *  @param { number } rowNumber : the row number as this appears in the spreadsheet it is being created from
 *  @param { string } [ testingStatus ] : the status on the testing of this file. Should be one of the following: NOT_TESTED, FULLY_TESTED, IN_PROGRESS, or PARTIAL
 *  @returns { SheetDataNode }
 *  @deprecated This function is not working right now 
 **/
function SheetDataNode(data, filename, complexity, rowNumber, testingStatus) { 
    var _pkgName = '';
    var _leftChild = null;
    var _rightChild = null;
    var _beenFound = false;
    var _rowNumber = rowNumber;
    var _files = [];

    // if there's only one argument, it better be an object, having the required fields
    if (arguments.length === 1) { 
      // it should have package field
      if ((data.package === undefined) || (data.package !== data.package.toString())) { 
        throw ReferenceError('only one argument was specified, but it is not an object that contains package');
      }
      // it should have files field
      if ((data.files === undefined) || (!Array.isArray(data.files))) { 
        throw ReferenceError('Called from the one-arg constructor, so files should be Array');
      }
      // that files field should itself be an object with the following fields: complexity and name
      for (var idx in data.files) { 
        if (data.files[idx].complexity !== parseInt(data.files[idx].complexity)) { 
          throw TypeError("complexity should be an integer");
        }
        if (data.files[idx].name !== data.files[idx].name.toString()) { 
          throw TypeError("name of file should be a string");
        }
      }

      // sort the array of files
      data.files.sort(fileSorter)

      // call the initialization function
      return SheetDataNode._init(data.package, data.files, parseInt(data.rowNumber));
    }
    // performing argument checking
    if (filename !== filename.toString()) throw TypeError("filename is supposed to be a String")
    if ((complexity !== undefined) && (complexity !== parseInt(complexity))) { 
      throw TypeError("complexity must be a number, or undefined")
    }

  // call the initialization function, constructing a single file object
  return SheetDataNode._init(data.toString(), [{
    complexity : complexity,
    name: filename, 
    testingStatus : testingStatus
  }])
}

// Helper private function that performs initialization
SheetDataNode._init = function(package, files, rowNumber) { 
  // bring in the variables
  var _pkgName = package;
  var _files = files;
  var _leftChild = null;
  var _rightChild = null;
  var _beenFound = false;
  var _rowNumber = rowNumber;

  // providing a function to add file
  _addFile = function(file) { 
    for (var f in _files) { 
      if (file.name < _files[f].name) { 
        _files.splice(f, 0, file)
        return 
      }
    }
    _files.push(file)
  }


  return {
    getRowNumber : function() { return _rowNumber; },
    getPackageName : function () { return _pkgName; },
    getFiles: function() { return _files; },
    addFile : _addFile,
    addFiles : function(files) { 
      if (!Array.isArray(files)) throw TypeError("files should be an Array")
      for (var idx in files) { 
        _addFile(files[idx])
      }
    },
    getLeftChild : function() { return _leftChild; },
    setLeftChild : function(node) { 
        _leftChild = node;
    },
    getRightChild : function() { return _rightChild; },
    setRightChild : function(node) { 
        _rightChild = node;
    },
    insertNode : function(node) { 
      // set the current node as the head node
      var currentNode = this;
      // while we are on a non-null node
      while (currentNode) { 
        // if the package of node is the same as that of currentNode
        if (currentNode.getPackageName() === node.getPackageName()) { 
          // simply add the files of node to currentNode._files
          currentNode.addFiles(node.getFiles())
          return
        }
        // if the package of node "comes before" that of currentNode, move to the left
        if (currentNode.getPackageName() > node.getPackageName()) { 
          // if the left child of node is defined, that becomes the current node
          if (currentNode.getLeftChild()) currentNode = currentNode.getLeftChild()
          // else construct it, and we're done
          else { 
            currentNode.setLeftChild(node)
            return
          }
        }
        // if the package of node "comes after" that of currentNode, move to the right
        if (currentNode.getPackageName() < node.getPackageName()) {
          // if the right child of node is defined, that becomes the current node
          if (currentNode.getRightChild()) currentNode = currentNode.getRightChild()
          // else construct it, and we're done
          else {
            currentNode.setRightChild(node)
            return 
          }
        }
        throw Error("Whoa, some infinite looping was about to happen!")
      }
    }
  }

}

UtilityFunctions.gs

/**
 *  Sorts file objects by their name property, alphabetically
 *  @param { { name : string } } lvalue
 *  @param { { name : string } } rvalue
 *  @returns { boolean } the lexical comparison of lvalue.name,rvalue.name
 **/ 
function fileSorter(lvalue, rvalue) {
  if (lvalue.name > rvalue.name) return 1;
  return (lvalue.name < rvalue.name) ? -1 : 0;
}

Problem

I'm unit-testing the code, with the failing test case consisting of the following steps :

construct a SheetDataNode node
construct another SheetDataNode otherNode with the same package name as the first, but different filename
insert otherNode into node
expectation: it now has two files
actual: it only has one: the original.
expectation: neither left nor right child nodes were set by this operation
actual : neither left nor right child nodes were set by this operation

The code to do the above looks like this:

  QUnit.test("inserting a node having the same package as the node it is assigned to",
             function() { 
               // create the base node
               var node = SheetDataNode("example", "main.go", 3, 1)
               // insert an other node, with identical package name
               var otherNode = SheetDataNode(node.getPackageName(), "logUtility.go", 12, 3)
               node.insertNode(otherNode)
               // node should contain two files, and neither a left child nor a right child
               deepEqual(node.getFiles().map(function(val) { 
                 return val.name
               }), 
                         ["logUtility.go", "main.go"], 
                         "node contains the right file names")
               equal(node.getFiles().length, 2, "A package got added to the node")
               ok(!node.getLeftChild(), "leftChild still unset")
               ok(!node.getRightChild(), "rightChild still unset")
             })

Here is screenshot of the failing assertions:

Remember that the method under test is like this:

insertNode : function(node) { 
      // set the current node as the head node
      var currentNode = this;
      // while we are on a non-null node
      while (currentNode) { 
        // if the package of node is the same as that of currentNode
        if (currentNode.getPackageName() === node.getPackageName()) { 
          // simply add the files of node to currentNode._files
          currentNode.addFiles(node.getFiles())
          return
        }
        // if the package of node "comes before" that of currentNode, move to the left
        if (currentNode.getPackageName() > node.getPackageName()) { 
          // if the left child of node is defined, that becomes the current node
          if (currentNode.getLeftChild()) currentNode = currentNode.getLeftChild()
          // else construct it, and we're done
          else { 
            currentNode.setLeftChild(node)
            return
          }
        }
        // if the package of node "comes after" that of currentNode, move to the right
        if (currentNode.getPackageName() < node.getPackageName()) {
          // if the right child of node is defined, that becomes the current node
          if (currentNode.getRightChild()) currentNode = currentNode.getRightChild()
          // else construct it, and we're done
          else {
            currentNode.setRightChild(node)
            return 
          }
        }
        throw Error("Whoa, some infinite looping was about to happen!")
      }

The test against the method addFiles, which has this code:

  QUnit.test("testing method addFiles",
             function() { 
               // create the base node
               var node = SheetDataNode("example", "main.go", 3, 1)
               // create an array of files to add
               const filesToAdd = [{
                 name : 'aFile.go',
                 complexity : 10
               }, {
                 name : 'anotherFile.go',
                 complexity : 10
               }, {
                 name : 'yetAnotherFile.go',
                 complexity : 10
               }]
               // is node.getFiles() an array?!
               ok(Array.isArray(node.getFiles()), "node.getFiles() is an array")

               // add the files
               node.addFiles(filesToAdd)
               Logger.log(node.getFiles())
               // node.getFiles() should be an Array
               ok(Array.isArray(node.getFiles()), "node.getFiles() is still an array")
               // node.getFiles should now contain filesToAdd
               equal(node.getFiles().length, 1 + filesToAdd.length, "node.getFiles().length increased by the length of the files to add")
             })

passes:

, as do the other tests against insertNode, meaning the problem might exist with how we try to reference currentNode in insertNode for array property modification. If so, I have no idea how else to reference, in Google Apps Script, the SheetDataNode to undergo state change

Solution

I was able to solve the problem, with inspiration from the MDN docs on closures, by changing the private function property declaration from :

_addFile = function(file) { 
    for (var f in _files) { 
      if (file.name < _files[f].name) { 
        _files.splice(f, 0, file)
        return 
      }
    }
    _files.push(file)
  }

function _addFile(file) { 
    for (var f in _files) { 
      if (file.name < _files[f].name) { 
        _files.splice(f, 0, file)
        return 
      }
    }
    _files.push(file)
  }

idk why this works, because I forgot the difference between declaring method like a function variable (what I was doing), and preceding the name of the method with function like it's any other function. I'll have to (re-)learn that...