Ensure placeholder properties are set for fp.convert() results. [closes

#3440]

fp/_baseConvert.js

@@ -136,8 +136,7 @@ function wrapImmutable(func, cloner) {
  * @returns {Function|Object} Returns the converted function or object.
  */
 function baseConvert(util, name, func, options) {
-  var setPlaceholder,
-      isLib = typeof name == 'function',
+  var isLib = typeof name == 'function',
       isObj = name === Object(name);
 
   if (isObj) {
@@ -158,10 +157,10 @@ function baseConvert(util, name, func, options) {
     'rearg': 'rearg' in options ? options.rearg : true
   };
 
-  var forceCurry = ('curry' in options) && options.curry,
+  var defaultHolder = isLib ? func : fallbackHolder,
+      forceCurry = ('curry' in options) && options.curry,
       forceFixed = ('fixed' in options) && options.fixed,
       forceRearg = ('rearg' in options) && options.rearg,
-      placeholder = isLib ? func : fallbackHolder,
       pristine = isLib ? func.runInContext() : undefined;
 
   var helpers = isLib ? func : {
@@ -466,7 +465,7 @@ function baseConvert(util, name, func, options) {
    * @param {Function} func The function to wrap.
    * @returns {Function} Returns the converted function.
    */
-  function wrap(name, func) {
+  function wrap(name, func, placeholder) {
     var result,
         realName = mapping.aliasToReal[name] || name,
         wrapped = func,
@@ -511,17 +510,15 @@ function baseConvert(util, name, func, options) {
       };
     }
     result.convert = createConverter(realName, func);
-    if (mapping.placeholder[realName]) {
-      setPlaceholder = true;
-      result.placeholder = func.placeholder = placeholder;
-    }
+    result.placeholder = func.placeholder = placeholder;
+
     return result;
   }
 
   /*--------------------------------------------------------------------------*/
 
   if (!isObj) {
-    return wrap(name, func);
+    return wrap(name, func, defaultHolder);
   }
   var _ = func;
 
@@ -531,7 +528,8 @@ function baseConvert(util, name, func, options) {
     each(mapping.aryMethod[aryKey], function(key) {
       var func = _[mapping.remap[key] || key];
       if (func) {
-        pairs.push([key, wrap(key, func)]);
+
+        pairs.push([key, wrap(key, func, _)]);
       }
     });
   });
@@ -557,9 +555,8 @@ function baseConvert(util, name, func, options) {
   });
 
   _.convert = convertLib;
-  if (setPlaceholder) {
-    _.placeholder = placeholder;
-  }
+  _.placeholder = _;
+
   // Assign aliases.
   each(keys(_), function(key) {
     each(mapping.realToAlias[key] || [], function(alias) {

fp/_mapping.js

@@ -261,16 +261,6 @@ exports.mutate = {
   }
 };
 
-/** Used to track methods with placeholder support */
-exports.placeholder = {
-  'bind': true,
-  'bindKey': true,
-  'curry': true,
-  'curryRight': true,
-  'partial': true,
-  'partialRight': true
-};
-
 /** Used to map real names to their aliases. */
 exports.realToAlias = (function() {
   var hasOwnProperty = Object.prototype.hasOwnProperty,

test/test-fp.js

@@ -233,25 +233,14 @@
       assert.strictEqual(add('2')('1'), '12');
     });
 
-    QUnit.test('should only add a `placeholder` property if needed', function(assert) {
+    QUnit.test('should add a `placeholder` property', function(assert) {
       assert.expect(2);
 
       if (!document) {
-        var methodNames = _.keys(mapping.placeholder),
-            expected = _.map(methodNames, _.constant(true));
-
-        var actual = _.map(methodNames, function(methodName) {
-          var object = {};
-          object[methodName] = _[methodName];
-
-          var lodash = convert(object);
-          return methodName in lodash;
-        });
-
-        assert.deepEqual(actual, expected);
-
         var lodash = convert({ 'add': _.add });
-        assert.notOk('placeholder' in lodash);
+
+        assert.strictEqual(lodash.placeholder, lodash);
+        assert.strictEqual(lodash.add.placeholder, lodash)
       }
       else {
         skipAssert(assert, 2);
@@ -645,7 +634,16 @@
       });
     });
 
-    _.forOwn(mapping.placeholder, function(truthy, methodName) {
+    var methodNames = [
+      'bind',
+      'bindKey',
+      'curry',
+      'curryRight',
+      'partial',
+      'partialRight'
+    ]
+
+    _.each(methodNames, function(methodName) {
       var func = fp[methodName];
 
       QUnit.test('fp.' + methodName + '` should have a `placeholder` property', function(assert) {