array-reduce.js

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/**
 * @fileoverview Test reduce and reduceRight
 */

function clone(v) {
  // Shallow-copies arrays, returns everything else verbatim.
  if (v instanceof Array) {
    // Shallow-copy an array.
    var newArray = new Array(v.length);
    for (var i in v) {
      newArray[i] = v[i];
    }
    return newArray;
  }
  return v;
}


// Creates a callback function for reduce/reduceRight that tests the number
// of arguments and otherwise behaves as "func", but which also
// records all calls in an array on the function (as arrays of arguments
// followed by result).
function makeRecorder(func, testName) {
  var record = [];
  var f = function recorder(a, b, i, s) {
    assertEquals(4, arguments.length,
                 testName + "(number of arguments: " + arguments.length + ")");
    assertEquals("number", typeof(i), testName + "(index must be number)");
    assertEquals(s[i], b, testName + "(current argument is at index)");
    if (record.length > 0) {
      var prevRecord = record[record.length - 1];
      var prevResult = prevRecord[prevRecord.length - 1];
      assertEquals(prevResult, a,
                   testName + "(prev result -> current input)");
    }
    var args = [clone(a), clone(b), i, clone(s)];
    var result = func.apply(this, arguments);
    args.push(clone(result));
    record.push(args);
    return result;
  };
  f.record = record;
  return f;
}


function testReduce(type,
                    testName,
                    expectedResult,
                    expectedCalls,
                    array,
                    combine,
                    init) {
  var rec = makeRecorder(combine);
  var result;
  var performsCall;
  if (arguments.length > 6) {
    result = array[type](rec, init);
  } else {
    result = array[type](rec);
  }
  var calls = rec.record;
  assertEquals(expectedCalls.length, calls.length,
               testName + " (number of calls)");
  for (var i = 0; i < expectedCalls.length; i++) {
    assertEquals(expectedCalls[i], calls[i],
                 testName + " (call " + (i + 1) + ")");
  }
  assertEquals(expectedResult, result, testName + " (result)");
}


function sum(a, b) { return a + b; }
function prod(a, b) { return a * b; }
function dec(a, b, i, arr) { return a + b * Math.pow(10, arr.length - i - 1); }
function accumulate(acc, elem, i) { acc[i] = elem; return acc; }

// ---- Test Reduce[Left]

var simpleArray = [2,4,6]

testReduce("reduce", "SimpleReduceSum", 12,
           [[0, 2, 0, simpleArray, 2],
            [2, 4, 1, simpleArray, 6],
            [6, 6, 2, simpleArray, 12]],
           simpleArray, sum, 0);

testReduce("reduce", "SimpleReduceProd", 48,
           [[1, 2, 0, simpleArray, 2],
            [2, 4, 1, simpleArray, 8],
            [8, 6, 2, simpleArray, 48]],
           simpleArray, prod, 1);

testReduce("reduce", "SimpleReduceDec", 246,
           [[0, 2, 0, simpleArray, 200],
            [200, 4, 1, simpleArray, 240],
            [240, 6, 2, simpleArray, 246]],
           simpleArray, dec, 0);

testReduce("reduce", "SimpleReduceAccumulate", simpleArray,
           [[[], 2, 0, simpleArray, [2]],
            [[2], 4, 1, simpleArray, [2, 4]],
            [[2,4], 6, 2, simpleArray, simpleArray]],
           simpleArray, accumulate, []);


testReduce("reduce", "EmptyReduceSum", 0, [], [], sum, 0);
testReduce("reduce", "EmptyReduceProd", 1, [], [], prod, 1);
testReduce("reduce", "EmptyReduceDec", 0, [], [], dec, 0);
testReduce("reduce", "EmptyReduceAccumulate", [], [], [], accumulate, []);

testReduce("reduce", "EmptyReduceSumNoInit", 0, [], [0], sum);
testReduce("reduce", "EmptyReduceProdNoInit", 1, [], [1], prod);
testReduce("reduce", "EmptyReduceDecNoInit", 0, [], [0], dec);
testReduce("reduce", "EmptyReduceAccumulateNoInit", [], [], [[]], accumulate);


var simpleSparseArray = [,,,2,,4,,6,,];
testReduce("reduce", "SimpleSparseReduceSum", 12,
           [[0, 2, 3, simpleSparseArray, 2],
            [2, 4, 5, simpleSparseArray, 6],
            [6, 6, 7, simpleSparseArray, 12]],
           simpleSparseArray, sum, 0);

testReduce("reduce", "SimpleSparseReduceProd", 48,
           [[1, 2, 3, simpleSparseArray, 2],
            [2, 4, 5, simpleSparseArray, 8],
            [8, 6, 7, simpleSparseArray, 48]],
           simpleSparseArray, prod, 1);

testReduce("reduce", "SimpleSparseReduceDec", 204060,
           [[0, 2, 3, simpleSparseArray, 200000],
            [200000, 4, 5, simpleSparseArray, 204000],
            [204000, 6, 7, simpleSparseArray, 204060]],
           simpleSparseArray, dec, 0);

testReduce("reduce", "SimpleSparseReduceAccumulate", [,,,2,,4,,6],
           [[[], 2, 3, simpleSparseArray, [,,,2]],
            [[,,,2], 4, 5, simpleSparseArray, [,,,2,,4]],
            [[,,,2,,4], 6, 7, simpleSparseArray, [,,,2,,4,,6]]],
           simpleSparseArray, accumulate, []);


testReduce("reduce", "EmptySparseReduceSumNoInit", 0, [], [,,0,,], sum);
testReduce("reduce", "EmptySparseReduceProdNoInit", 1, [], [,,1,,], prod);
testReduce("reduce", "EmptySparseReduceDecNoInit", 0, [], [,,0,,], dec);
testReduce("reduce", "EmptySparseReduceAccumulateNoInit",
           [], [], [,,[],,], accumulate);


var verySparseArray = [];
verySparseArray.length = 10000;
verySparseArray[2000] = 2;
verySparseArray[5000] = 4;
verySparseArray[9000] = 6;
var verySparseSlice2 = verySparseArray.slice(0, 2001);
var verySparseSlice4 = verySparseArray.slice(0, 5001);
var verySparseSlice6 = verySparseArray.slice(0, 9001);

testReduce("reduce", "VerySparseReduceSum", 12,
           [[0, 2, 2000, verySparseArray, 2],
            [2, 4, 5000, verySparseArray, 6],
            [6, 6, 9000, verySparseArray, 12]],
           verySparseArray, sum, 0);

testReduce("reduce", "VerySparseReduceProd", 48,
           [[1, 2, 2000, verySparseArray, 2],
            [2, 4, 5000, verySparseArray, 8],
            [8, 6, 9000, verySparseArray, 48]],
           verySparseArray, prod, 1);

testReduce("reduce", "VerySparseReduceDec", Infinity,
           [[0, 2, 2000, verySparseArray, Infinity],
            [Infinity, 4, 5000, verySparseArray, Infinity],
            [Infinity, 6, 9000, verySparseArray, Infinity]],
           verySparseArray, dec, 0);

testReduce("reduce", "VerySparseReduceAccumulate",
           verySparseSlice6,
           [[[], 2, 2000, verySparseArray, verySparseSlice2],
            [verySparseSlice2, 4, 5000, verySparseArray, verySparseSlice4],
            [verySparseSlice4, 6, 9000, verySparseArray, verySparseSlice6]],
           verySparseArray, accumulate, []);


testReduce("reduce", "VerySparseReduceSumNoInit", 12,
           [[2, 4, 5000, verySparseArray, 6],
            [6, 6, 9000, verySparseArray, 12]],
           verySparseArray, sum);

testReduce("reduce", "VerySparseReduceProdNoInit", 48,
           [[2, 4, 5000, verySparseArray, 8],
            [8, 6, 9000, verySparseArray, 48]],
           verySparseArray, prod);

testReduce("reduce", "VerySparseReduceDecNoInit", Infinity,
           [[2, 4, 5000, verySparseArray, Infinity],
            [Infinity, 6, 9000, verySparseArray, Infinity]],
           verySparseArray, dec);

testReduce("reduce", "SimpleSparseReduceAccumulateNoInit",
           2,
           [[2, 4, 5000, verySparseArray, 2],
            [2, 6, 9000, verySparseArray, 2]],
           verySparseArray, accumulate);


// ---- Test ReduceRight

testReduce("reduceRight", "SimpleReduceRightSum", 12,
           [[0, 6, 2, simpleArray, 6],
            [6, 4, 1, simpleArray, 10],
            [10, 2, 0, simpleArray, 12]],
           simpleArray, sum, 0);

testReduce("reduceRight", "SimpleReduceRightProd", 48,
           [[1, 6, 2, simpleArray, 6],
            [6, 4, 1, simpleArray, 24],
            [24, 2, 0, simpleArray, 48]],
           simpleArray, prod, 1);

testReduce("reduceRight", "SimpleReduceRightDec", 246,
           [[0, 6, 2, simpleArray, 6],
            [6, 4, 1, simpleArray, 46],
            [46, 2, 0, simpleArray, 246]],
           simpleArray, dec, 0);

testReduce("reduceRight", "SimpleReduceRightAccumulate", simpleArray,
           [[[], 6, 2, simpleArray, [,,6]],
            [[,,6], 4, 1, simpleArray, [,4,6]],
            [[,4,6], 2, 0, simpleArray, simpleArray]],
           simpleArray, accumulate, []);


testReduce("reduceRight", "EmptyReduceRightSum", 0, [], [], sum, 0);
testReduce("reduceRight", "EmptyReduceRightProd", 1, [], [], prod, 1);
testReduce("reduceRight", "EmptyReduceRightDec", 0, [], [], dec, 0);
testReduce("reduceRight", "EmptyReduceRightAccumulate", [],
           [], [], accumulate, []);

testReduce("reduceRight", "EmptyReduceRightSumNoInit", 0, [], [0], sum);
testReduce("reduceRight", "EmptyReduceRightProdNoInit", 1, [], [1], prod);
testReduce("reduceRight", "EmptyReduceRightDecNoInit", 0, [], [0], dec);
testReduce("reduceRight", "EmptyReduceRightAccumulateNoInit",
           [], [], [[]], accumulate);


testReduce("reduceRight", "SimpleSparseReduceRightSum", 12,
           [[0, 6, 7, simpleSparseArray, 6],
            [6, 4, 5, simpleSparseArray, 10],
            [10, 2, 3, simpleSparseArray, 12]],
           simpleSparseArray, sum, 0);

testReduce("reduceRight", "SimpleSparseReduceRightProd", 48,
           [[1, 6, 7, simpleSparseArray, 6],
            [6, 4, 5, simpleSparseArray, 24],
            [24, 2, 3, simpleSparseArray, 48]],
           simpleSparseArray, prod, 1);

testReduce("reduceRight", "SimpleSparseReduceRightDec", 204060,
           [[0, 6, 7, simpleSparseArray, 60],
            [60, 4, 5, simpleSparseArray, 4060],
            [4060, 2, 3, simpleSparseArray, 204060]],
           simpleSparseArray, dec, 0);

testReduce("reduceRight", "SimpleSparseReduceRightAccumulate", [,,,2,,4,,6],
           [[[], 6, 7, simpleSparseArray, [,,,,,,,6]],
            [[,,,,,,,6], 4, 5, simpleSparseArray, [,,,,,4,,6]],
            [[,,,,,4,,6], 2, 3, simpleSparseArray, [,,,2,,4,,6]]],
           simpleSparseArray, accumulate, []);


testReduce("reduceRight", "EmptySparseReduceRightSumNoInit",
           0, [], [,,0,,], sum);
testReduce("reduceRight", "EmptySparseReduceRightProdNoInit",
           1, [], [,,1,,], prod);
testReduce("reduceRight", "EmptySparseReduceRightDecNoInit",
           0, [], [,,0,,], dec);
testReduce("reduceRight", "EmptySparseReduceRightAccumulateNoInit",
           [], [], [,,[],,], accumulate);


var verySparseSuffix6 = [];
verySparseSuffix6[9000] = 6;
var verySparseSuffix4 = [];
verySparseSuffix4[5000] = 4;
verySparseSuffix4[9000] = 6;
var verySparseSuffix2 = verySparseSlice6;


testReduce("reduceRight", "VerySparseReduceRightSum", 12,
           [[0, 6, 9000, verySparseArray, 6],
            [6, 4, 5000, verySparseArray, 10],
            [10, 2, 2000, verySparseArray, 12]],
           verySparseArray, sum, 0);

testReduce("reduceRight", "VerySparseReduceRightProd", 48,
           [[1, 6, 9000, verySparseArray, 6],
            [6, 4, 5000, verySparseArray, 24],
            [24, 2, 2000, verySparseArray, 48]],
           verySparseArray, prod, 1);

testReduce("reduceRight", "VerySparseReduceRightDec", Infinity,
           [[0, 6, 9000, verySparseArray, Infinity],
            [Infinity, 4, 5000, verySparseArray, Infinity],
            [Infinity, 2, 2000, verySparseArray, Infinity]],
           verySparseArray, dec, 0);

testReduce("reduceRight", "VerySparseReduceRightAccumulate",
           verySparseSuffix2,
           [[[], 6, 9000, verySparseArray, verySparseSuffix6],
            [verySparseSuffix6, 4, 5000, verySparseArray, verySparseSuffix4],
            [verySparseSuffix4, 2, 2000, verySparseArray, verySparseSuffix2]],
           verySparseArray, accumulate, []);


testReduce("reduceRight", "VerySparseReduceRightSumNoInit", 12,
           [[6, 4, 5000, verySparseArray, 10],
            [10, 2, 2000, verySparseArray, 12]],
           verySparseArray, sum);

testReduce("reduceRight", "VerySparseReduceRightProdNoInit", 48,
           [[6, 4, 5000, verySparseArray, 24],
            [24, 2, 2000, verySparseArray, 48]],
           verySparseArray, prod);

testReduce("reduceRight", "VerySparseReduceRightDecNoInit", Infinity,
           [[6, 4, 5000, verySparseArray, Infinity],
            [Infinity, 2, 2000, verySparseArray, Infinity]],
           verySparseArray, dec);

testReduce("reduceRight", "SimpleSparseReduceRightAccumulateNoInit",
           6,
           [[6, 4, 5000, verySparseArray, 6],
            [6, 2, 2000, verySparseArray, 6]],
           verySparseArray, accumulate);


// undefined is an element
var undefArray = [,,undefined,,undefined,,];

testReduce("reduce", "SparseUndefinedReduceAdd", NaN,
           [[0, undefined, 2, undefArray, NaN],
            [NaN, undefined, 4, undefArray, NaN],
           ],
           undefArray, sum, 0);

testReduce("reduceRight", "SparseUndefinedReduceRightAdd", NaN,
           [[0, undefined, 4, undefArray, NaN],
            [NaN, undefined, 2, undefArray, NaN],
           ], undefArray, sum, 0);

testReduce("reduce", "SparseUndefinedReduceAddNoInit", NaN,
           [[undefined, undefined, 4, undefArray, NaN],
           ], undefArray, sum);

testReduce("reduceRight", "SparseUndefinedReduceRightAddNoInit", NaN,
           [[undefined, undefined, 2, undefArray, NaN],
           ], undefArray, sum);


// Ignore non-array properties:

var arrayPlus = [1,2,,3];
arrayPlus[-1] = NaN;
arrayPlus[Math.pow(2,32)] = NaN;
arrayPlus[NaN] = NaN;
arrayPlus["00"] = NaN;
arrayPlus["02"] = NaN;
arrayPlus["-0"] = NaN;

testReduce("reduce", "ArrayWithNonElementPropertiesReduce", 6,
           [[0, 1, 0, arrayPlus, 1],
            [1, 2, 1, arrayPlus, 3],
            [3, 3, 3, arrayPlus, 6],
           ], arrayPlus, sum, 0);

testReduce("reduceRight", "ArrayWithNonElementPropertiesReduceRight", 6,
           [[0, 3, 3, arrayPlus, 3],
            [3, 2, 1, arrayPlus, 5],
            [5, 1, 0, arrayPlus, 6],
           ], arrayPlus, sum, 0);


// Test error conditions:

try {
  [1].reduce("not a function");
  assertUnreachable("Reduce callback not a function not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduce callback not a function not throwing TypeError");
  assertEquals("called_non_callable", e.type,
               "reduce non function TypeError type");
}

try {
  [1].reduceRight("not a function");
  assertUnreachable("ReduceRight callback not a function not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduceRight callback not a function not throwing TypeError");
  assertEquals("called_non_callable", e.type,
               "reduceRight non function TypeError type");
}


try {
  [].reduce(sum);
  assertUnreachable("Reduce no initial value not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduce no initial value not throwing TypeError");
  assertEquals("reduce_no_initial", e.type,
               "reduce no initial TypeError type");
}

try {
  [].reduceRight(sum);
  assertUnreachable("ReduceRight no initial value not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduceRight no initial value not throwing TypeError");
  assertEquals("reduce_no_initial", e.type,
               "reduceRight no initial TypeError type");
}


try {
  [,,,].reduce(sum);
  assertUnreachable("Reduce sparse no initial value not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduce sparse no initial value not throwing TypeError");
  assertEquals("reduce_no_initial", e.type,
               "reduce no initial TypeError type");
}

try {
  [,,,].reduceRight(sum);
  assertUnreachable("ReduceRight sparse no initial value not throwing");
} catch (e) {
  assertTrue(e instanceof TypeError,
             "reduceRight sparse no initial value not throwing TypeError");
  assertEquals("reduce_no_initial", e.type,
               "reduceRight no initial TypeError type");
}


// Array changing length

function manipulator(a, b, i, s) {
  if (s.length % 2) {
    s[s.length * 3] = i;
  } else {
    s.length = s.length >> 1;
  }
  return a + b;
}

var arr = [1, 2, 3, 4];
testReduce("reduce", "ArrayManipulationShort", 3,
           [[0, 1, 0, [1, 2, 3, 4], 1],
            [1, 2, 1, [1, 2], 3],
           ], arr, manipulator, 0);

var arr = [1, 2, 3, 4, 5];
testReduce("reduce", "ArrayManipulationLonger", 10,
           [[0, 1, 0, [1, 2, 3, 4, 5], 1],
            [1, 2, 1, [1, 2, 3, 4, 5,,,,,,,,,,, 0], 3],
            [3, 3, 2, [1, 2, 3, 4, 5,,,,], 6],
            [6, 4, 3, [1, 2, 3, 4], 10],
           ], arr, manipulator, 0);

function extender(a, b, i, s) {
  s[s.length] = s.length;
  return a + b;
}

var arr = [1, 2, 3, 4];
testReduce("reduce", "ArrayManipulationExtender", 10,
           [[0, 1, 0, [1, 2, 3, 4], 1],
            [1, 2, 1, [1, 2, 3, 4, 4], 3],
            [3, 3, 2, [1, 2, 3, 4, 4, 5], 6],
            [6, 4, 3, [1, 2, 3, 4, 4, 5, 6], 10],
           ], arr, extender, 0);