Update avg to work with generators and count after sort.

src/Collection/CollectionTrait.php

@@ -195,39 +195,42 @@ public function min($callback, $type = SORT_NUMERIC)
      */
     public function avg($matcher = null)
     {
-        $iterator = $this->unwrap();
-        $count = $iterator instanceof Countable ?
-            count($iterator) :
-            iterator_count($iterator);
+        $result = $this;
+        if ($matcher != null) {
+            $result = $result->extract($matcher);
+        }
+        $result = $result
+            ->reduce(function ($acc, $current) {
+                list($count, $sum) = $acc;
+
+                return [$count + 1, $sum + $current];
+            }, [0, 0]);
 
-        if ($count === 0) {
+        if ($result[0] === 0) {
             return null;
         }
 
-        return $this->sumOf($matcher) / $count;
+        return $result[1] / $result[0];
     }
 
     /**
      * {@inheritDoc}
      */
     public function median($matcher = null)
     {
-        $iterator = $this->unwrap();
-        $count = $iterator instanceof Countable ?
-            count($iterator) :
-            iterator_count($iterator);
-
-        if ($count === 0) {
-            return null;
-        }
-
-        $middle = (int)($count / 2);
         $elements = $this;
         if ($matcher != null) {
             $elements = $elements->extract($matcher);
         }
         $values = $elements->toList();
         sort($values);
+        $count = count($values);
+
+        if ($count === 0) {
+            return null;
+        }
+
+        $middle = (int)($count / 2);
 
         if ($count % 2) {
             return $values[$middle];

tests/TestCase/Collection/CollectionTest.php

@@ -60,13 +60,28 @@ public function testArrayIsWrapped()
     }
 
     /**
-     * Tests that it is possible to convert an array into a collection
+     * Provider for average tests
      *
-     * @return void
+     * @return array
      */
-    public function testAvg()
+    public function avgProvider()
     {
         $items = [1, 2, 3];
+
+        return [
+            'array' => [$items],
+            'iterator' => [$this->yieldItems($items)]
+        ];
+    }
+
+    /**
+     * ests the avg method
+     *
+     * @dataProvider avgProvider
+     * @return void
+     */
+    public function testAvg($items)
+    {
         $collection = new Collection($items);
         $this->assertEquals(2, $collection->avg());
 
@@ -76,32 +91,84 @@ public function testAvg()
         $items = [['foo' => 1], ['foo' => 2], ['foo' => 3]];
         $collection = new Collection($items);
         $this->assertEquals(2, $collection->avg('foo'));
-        $items = [
-            ['invoice' => ['total' => 100]],
-            ['invoice' => ['total' => 200]]
-        ];
+    }
 
-        $this->assertEquals(150, (new Collection($items))->avg('invoice.total'));
+    /**
+     * Provider for average tests with use of a matcher
+     *
+     * @return array
+     */
+    public function avgWithMatcherProvider()
+    {
+        $items = [['foo' => 1], ['foo' => 2], ['foo' => 3]];
+
+        return [
+            'array' => [$items],
+            'iterator' => [$this->yieldItems($items)]
+        ];
     }
 
     /**
-     * Tests that it is possible to convert an array into a collection
+     * ests the avg method
      *
+     * @dataProvider avgWithMatcherProvider
      * @return void
      */
-    public function testMedian()
+    public function testAvgWithMatcher($items)
+    {
+        $collection = new Collection($items);
+        $this->assertEquals(2, $collection->avg('foo'));
+    }
+
+    /**
+     * Provider for some median tests
+     *
+     * @return array
+     */
+    public function medianProvider()
     {
         $items = [5, 2, 4];
+
+        return [
+            'array' => [$items],
+            'iterator' => [$this->yieldItems($items)]
+        ];
+    }
+
+    /**
+     * Tests the median method
+     *
+     * @dataProvider medianProvider
+     * @return void
+     */
+    public function testMedian($items)
+    {
         $collection = new Collection($items);
         $this->assertEquals(4, $collection->median());
 
         $collection = new Collection([]);
         $this->assertNull($collection->median());
+    }
 
-        $items = [1, 2, 3, 4];
+    /**
+     * Tests the median method
+     *
+     * @dataProvider simpleProvider
+     * @return void
+     */
+    public function testMedianEven($items)
+    {
         $collection = new Collection($items);
         $this->assertEquals(2.5, $collection->median());
+    }
 
+    /**
+     * Provider for median tests with use of a matcher
+     *
+     * @return array
+     */
+    public function medianWithMatcherProvider()
+    {
         $items = [
             ['invoice' => ['total' => 400]],
             ['invoice' => ['total' => 500]],
@@ -110,6 +177,20 @@ public function testMedian()
             ['invoice' => ['total' => 333]]
         ];
 
+        return [
+            'array' => [$items],
+            'iterator' => [$this->yieldItems($items)]
+        ];
+    }
+
+    /**
+     * Tests the median method
+     *
+     * @dataProvider medianWithMatcherProvider
+     * @return void
+     */
+    public function testMedianWithMatcher($items)
+    {
         $this->assertEquals(333, (new Collection($items))->median('invoice.total'));
     }