Fix flow and flowRight parameter handling (lodash#4445)

* Enable flow and flowRight tests

* Remove flow and flowRight tests for default value and shortcut fusion

* Use native rest parameters / spread operator in flow and flowRight

* Fix syntax of flow and flowRight examples

Author: blikblum

flow.js

@@ -10,15 +10,17 @@
  * @see flowRight
  * @example
  *
+ * import add from 'lodash/add'
+ * 
  * function square(n) {
  *   return n * n
  * }
  *
- * const addSquare = flow([add, square])
+ * const addSquare = flow(add, square)
  * addSquare(1, 2)
  * // => 9
  */
-function flow(funcs) {
+function flow(...funcs) {
   const length = funcs ? funcs.length : 0
   let index = length
   while (index--) {

flowRight.js

@@ -11,16 +11,18 @@ import flow from './flow.js'
  * @see flow
  * @example
  *
+ * import add from 'lodash/add'
+ * 
  * function square(n) {
  *   return n * n
  * }
  *
- * const addSquare = flowRight([square, add])
+ * const addSquare = flowRight(square, add)
  * addSquare(1, 2)
  * // => 9
  */
-function flowRight(funcs) {
-  return flow(funcs.reverse())
+function flowRight(...funcs) {
+  return flow(...funcs.reverse())
 }
 
 export default flowRight

test/flow-methods.js

@@ -0,0 +1,53 @@
+import assert from 'assert';
+import lodashStable from 'lodash';
+import { add, square, noop, identity } from './utils.js';
+import head from '../head.js';
+import map from '../map.js';
+import uniq from '../uniq.js';
+import flow from '../flow.js';
+import flowRight from '../flowRight.js';
+
+const methods = {
+  flow,
+  flowRight
+}
+
+describe('flow methods', function() {
+  lodashStable.each(['flow', 'flowRight'], function(methodName) {
+    var func = methods[methodName],
+        isFlow = methodName == 'flow';
+
+    it('`_.' + methodName + '` should supply each function with the return value of the previous', function() {
+      var fixed = function(n) { return n.toFixed(1); },
+          combined = isFlow ? func(add, square, fixed) : func(fixed, square, add);
+
+      assert.strictEqual(combined(1, 2), '9.0');
+    });
+
+    it('`_.' + methodName + '` should return a new function', function() {
+      assert.notStrictEqual(func(noop), noop);
+    });
+
+    it('`_.' + methodName + '` should work with a curried function and `_.head`', function() {
+      var curried = lodashStable.curry(identity);
+
+      var combined = isFlow
+        ? func(head, curried)
+        : func(curried, head);
+
+      assert.strictEqual(combined([1]), 1);
+    });
+
+    it('`_.' + methodName + '` should work with curried functions with placeholders', function() {
+      var curried = lodashStable.curry(lodashStable.ary(map, 2), 2),
+          getProp = curried(curried.placeholder, (value) => value.a),
+          objects = [{ 'a': 1 }, { 'a': 2 }, { 'a': 1 }];
+
+      var combined = isFlow
+        ? func(getProp, uniq)
+        : func(uniq, getProp);
+
+      assert.deepStrictEqual(combined(objects), [1, 2]);
+    });
+  });
+});