Interface implementations were not saved.

Because interface implementations were not stored in $loadedClasses, for every reference to the interface the implementing class was re-instantiated.

src/DependencyInjection.php

@@ -6,6 +6,11 @@
 use ReflectionException;
 use RuntimeException;
 
+/**
+ * Class DependencyInjection
+ *
+ * @package Devorto\DependencyInjection
+ */
 class DependencyInjection
 {
     /**
@@ -68,6 +73,7 @@ public static function instantiate(string $class)
             }
 
             // Overwrite interface with class.
+            $interface = $class;
             $class = static::$interfaceImplementations[$class];
 
             try {
@@ -79,6 +85,11 @@ public static function instantiate(string $class)
 
         $arguments = $reflection->getConstructor();
         if (empty($arguments)) {
+            // If the current class is an interface implementation also save the interface class.
+            if (isset($interface)) {
+                return static::$loadedClasses[$interface] = static::$loadedClasses[$class] = new $class;
+            }
+
             return static::$loadedClasses[$class] = new $class;
         }
 
@@ -126,6 +137,11 @@ public static function instantiate(string $class)
             }
         }
 
+        // If the current class is an interface implementation also save the interface class.
+        if (isset($interface)) {
+            return static::$loadedClasses[$interface] = static::$loadedClasses[$class] = new $class(...$parameters);
+        }
+
         return static::$loadedClasses[$class] = new $class(...$parameters);
     }
 

src/KeyValueStorage.php

@@ -6,6 +6,11 @@
 use Iterator;
 use Serializable;
 
+/**
+ * Class KeyValueStorage
+ *
+ * @package Devorto\DependencyInjection
+ */
 class KeyValueStorage implements Iterator, Serializable
 {
     /**