librarySystemWithDependencies.html

<script src="simpletest.js"></script>
<script>

  /*
  The librarySystem should be able to store libraries with dependencies and return the library if called

  Syntax:
    Formula: librarySystem(libraryName, dependencyArray, callbackLibrary)

    Arguments: 
      libraryName
      dependencyArray
      callbackLibrary

    Return Value: The library of libraryName, if adding library, it should return undefined

  Tests:
    LibraryName:
      It should take a string as the first argument [DONE]
      It should return the library if called and the library exists [DONE]
      It should throw an error if the library is called and the library does not exist [DONE]
    dependencyArray:
      It should take an array as the second argument [DONE]
      It should load the dependencies into the callbackLibrary [DONE]
    callbackLibrary:
      It should take a function as the third argument [DONE]
      It should store the callbackLibrary return value into the libraryStorage [DONE]
  */

  (function() {
    var libraryStorage = {};

    function librarySystem(libraryName, dependencyArray, callbackLibrary) {

      // Check if first argument is a string
      if (typeof libraryName !== 'string') {
        throw new TypeError('I am not a string');
      }

      // Adding library to libraryStorage
      if (arguments.length > 1) {

        // Check if second argument is an array
        if (!Array.isArray(dependencyArray)) {
          throw new TypeError('I am not an array');
        }

        // Replaces the dependencyArray names with the dependent library objects
        for (var i = 0; i < dependencyArray.length; i++) {
          dependencyArray[i] = librarySystem(dependencyArray[i]);
        }

        // Storing the library with the dependent libraries
        libraryStorage[libraryName] = callbackLibrary(...dependencyArray);
      }

      // Accessing library from libraryStorage
      else {
        if (libraryStorage[libraryName]) {
          return libraryStorage[libraryName];
        }
        else {
          throw new Error('libraryName not in libraryStorage')
        }
      }
    }
    window.librarySystem = librarySystem;
  })();


  tests({
    'It should take a string as the first argument': function () {
      var isTypeError = false;
      try {
        librarySystem(123);
      }
      catch (e) {
        isTypeError = e instanceof TypeError;
      }
      eq(isTypeError, true);
    },

    'It should return the library if called and the library exists': function() {
      librarySystem('testLibrary', [], function() {return 'testValue'});
      eq(librarySystem('testLibrary'), 'testValue');
    },

    'It should throw an error if the library is called and the library does not exist': function() {
      var isError = false;
      try {
        librarySystem('doesNotExist');
      }
      catch (e) {
        isError = e instanceof Error;
      }
      eq(isError, true);
    },

    'It should take an array as the second argument': function() {
      var isTypeError = false;
      try {
        librarySystem('libraryName', 'notAnArray');
      }
      catch (e) {
        isTypeError = e instanceof TypeError;
      }
      eq(isTypeError, true);
    },

    'It should load the dependencies into the callbackLibrary': function() {
      librarySystem('name', [], function() {
        return 'Xavier';
      });

      librarySystem('country', [], function() {
        return 'Singapore';
      });

      librarySystem('countryBlurb', ['name', 'country'], function(name, country) {
        return name + ' lives in ' + country;
      });

      eq(librarySystem('countryBlurb'), 'Xavier lives in Singapore');
    },

    'It should take a function as the third argument': function() {
      var isTypeError = false;
      try {
        librarySystem('testLibrary', [], 'I am not a function');
      }
      catch (e) {
        isTypeError = e instanceof TypeError;
      }
      eq(isTypeError, true);
    },

    'It should store the callbackLibrary return value into the libraryStorage': function() {
      librarySystem('testLibrary2', [], function() {return 'anotherTestValue'});
      eq(librarySystem('testLibrary2'), 'anotherTestValue');
    }

  });
</script>