Improved exception handling

tests/OfflineTests/ObjectRetrieverMockTest.php

@@ -9,6 +9,7 @@ namespace CloudObjects\SDK;
 use ML\IRI\IRI;
 use GuzzleHttp\Client, GuzzleHttp\Handler\MockHandler,
     GuzzleHttp\HandlerStack, GuzzleHttp\Psr7\Response;
+use CloudObjects\SDK\Exceptions\CoreAPIException;
 
 class ObjectRetrieverMockTest extends \PHPUnit\Framework\TestCase {
 
@@ -50,4 +51,23 @@ class ObjectRetrieverMockTest extends \PHPUnit\Framework\TestCase {
         $this->assertNull($object->getString('urn:example:nonexistingvalue'));
     }
 
+    public function testGetNonExistingResource() {
+        $this->setMockResponse(new Response(404));
+
+        // should return "null"        
+        $coid = new IRI('coid://nonexistingresource.example.com');
+
+        $object = $this->retriever->getObjectNode($coid);
+        $this->assertNull($object);
+    }
+
+    public function testWhenAPIThrowsError() {
+        $this->setMockResponse(new Response(500));
+
+        $coid = new IRI('coid://nonexistingresource.example.com');
+
+        $this->expectException(CoreAPIException::class);
+        $this->retriever->getObjectNode($coid);
+    }
+
 }