findPivot.js

/////////////////////////////////////////////////////////////
// Alphabetical Words
// ----------------------------------------------------------
// I have an array of words that are mostly alphabetical,
// except they start somewhere in the middle of the alphabet,
// reach the end, and then start from the beginning of the
// alphabet.
//
// In other words, this is an alphabetically ordered array
// that has been "rotated." For example:
// ['dog','eagle','falcon', /*PIVOT*/ 'apple','bear','cat']
//
// Write a function that returns the index of the 'pivot'
//
/////////////////////////////////////////////////////////////

var findPivotedWord = function (array, start, end) {
  // TODO: IMPLEMENT
};

/////////////////////////////////////////////////////////////
// TEST CASES
/////////////////////////////////////////////////////////////

var tests = [{
  inputs: ['cat','dog','eagle','falcon','goat','apple','bear'],
  expected: 4
}, {
  inputs: ['dog','eagle','falcon','goat','hope','apple','bear','cat'],
  expected: 4
}, {
  inputs: ['dog','eagle','falcon','goat','hope'],
  expected: null
}, {
  inputs: ['indigo','dog','eagle','falcon','goat','hope'],
  expected: 0
}, {
  inputs: ['dog','eagle','falcon','apple','bear','cat'],
  expected: 2
}];

var tester = function (testCase, functionToTest) {
  var testResult = functionToTest(testCase.inputs);
  return expectToBeEqual(testResult, testCase.expected);
};

var expectToBeEqual = function (a, b) {
  return JSON.stringify(a) === JSON.stringify(b);
};

tests.forEach(function (test, i) {
  console.log('Test #' + i + ' PASS? ', tester(test, findPivotedWord));
});