Refector code and implement modal average

src/Average.php

@@ -9,7 +9,7 @@ class Average
      * @param array $numbers Array of numbers
      * @return float Mean average
      */
-    public function mean(array $numbers)
+    public function mean(array $numbers): float
     {
         return array_sum($numbers) / count($numbers);
     }
@@ -19,16 +19,25 @@ public function mean(array $numbers)
      * @param array $numbers Array of numbers
      * @return float Median average
      */
-    public function median(array $numbers)
+    public function median(array $numbers): float
     {
         sort($numbers);
         $size = count($numbers);
         if ($size % 2) {
             return $numbers[$size / 2];
-        } else {
-            return $this->mean(
+        }
+        return $this->mean(
                 array_slice($numbers, ($size / 2) - 1, 2)
             );
-        }
+    }
+    /**
+     * Calculate the median average
+     * @param array $numbers Array of numbers
+     * @return float Median average
+     */
+    public function mode(array $numbers): int
+    {
+        $values = array_count_values($numbers);
+        return array_search(max($values), $values);
     }
 }

tests/AverageTest.php

@@ -18,9 +18,21 @@ public function testCalculationOfMean()
         $this->assertEquals(4.4, $this->Average->mean($numbers));
     }
 
-    public function testCalculationOfMedian()
+    public function testCalculationOfMedianForOddNumberOfValues()
     {
         $numbers = [3, 7, 6, 1, 5];
         $this->assertEquals(5, $this->Average->median($numbers));
     }
+
+    public function testCalculationOfMedianForEvenNumberOfValues()
+    {
+        $numbers = [3, 7, 6, 5];
+        $this->assertEquals(5.5, $this->Average->median($numbers));
+    }
+
+    public function testCalculationOfMode()
+    {
+        $numbers = [1, 3, 3, 3, 4, 4, 6, 6, 9];
+        $this->assertEquals(3, $this->Average->mode($numbers));
+    }
 }