Ensure _.divide and _.multiply return 1 when no arguments are specified. [closes #2405]

lodash.js

@@ -4783,13 +4783,14 @@
      *
      * @private
      * @param {Function} operator The function to perform the operation.
+     * @param {number} [defaultValue] The value used for `undefined` arguments.
      * @returns {Function} Returns the new mathematical operation function.
      */
-    function createMathOperation(operator) {
+    function createMathOperation(operator, defaultValue) {
       return function(value, other) {
         var result;
         if (value === undefined && other === undefined) {
-          return 0;
+          return defaultValue;
         }
         if (value !== undefined) {
           result = value;
@@ -15533,7 +15534,7 @@
      */
     var add = createMathOperation(function(augend, addend) {
       return augend + addend;
-    });
+    }, 0);
 
     /**
      * Computes `number` rounded up to `precision`.
@@ -15575,7 +15576,7 @@
      */
     var divide = createMathOperation(function(dividend, divisor) {
       return dividend / divisor;
-    });
+    }, 1);
 
     /**
      * Computes `number` rounded down to `precision`.
@@ -15768,7 +15769,7 @@
      */
     var multiply = createMathOperation(function(multiplier, multiplicand) {
       return multiplier * multiplicand;
-    });
+    }, 1);
 
     /**
      * Computes `number` rounded to `precision`.
@@ -15810,7 +15811,7 @@
      */
     var subtract = createMathOperation(function(minuend, subtrahend) {
       return minuend - subtrahend;
-    });
+    }, 0);
 
     /**
      * Computes the sum of the values in `array`.

test/test.js

@@ -21217,12 +21217,13 @@
   QUnit.module('math operator methods');
 
   lodashStable.each(['add', 'divide', 'multiply', 'subtract'], function(methodName) {
-    var func = _[methodName];
+    var func = _[methodName],
+        isAddSub = methodName == 'add' || methodName == 'subtract';
 
-    QUnit.test('`_.' + methodName + '` should return `0` when no arguments are given', function(assert) {
+    QUnit.test('`_.' + methodName + '` should return `' + (isAddSub ? 0 : 1) + '` when no arguments are given', function(assert) {
       assert.expect(1);
 
-      assert.strictEqual(func(), 0);
+      assert.strictEqual(func(), isAddSub ? 0 : 1);
     });
 
     QUnit.test('`_.' + methodName + '` should work with only one defined argument', function(assert) {