Be more informative when credentials have not been found

CHANGELOG.md

@@ -1,5 +1,10 @@
 # CHANGELOG
 
+## Unreleased
+
+* When the credentials file has not been found, a `CredentialsNotFound` exception is thrown,
+  including the information which paths have been tried.
+
 ## 3.0.0 - 2017-04-22
 
 * Moved all classes inside the `Kreait` namespace to avoid possible conflicts with official Firebase PHP libraries 

src/Firebase/Exception/CredentialsNotFound.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Kreait\Firebase\Exception;
+
+use Kreait\Firebase\Factory;
+use Throwable;
+
+class CredentialsNotFound extends LogicException
+{
+    /**
+     * @var string[]
+     */
+    private $triedPaths;
+
+    public function __construct($triedPaths, $message = '', $code = 0, Throwable $previous = null)
+    {
+        $message = $message ?: sprintf(
+            'No service account has been found. Tried [%s]. Please set the path to a valid service account credentials file with %s::%s()',
+            implode(', ', $triedPaths), Factory::class, 'withCredentials($path)'
+        );
+
+        parent::__construct($message, $code, $previous);
+
+        $this->triedPaths = $triedPaths;
+    }
+
+    /**
+     * @return \string[]
+     */
+    public function getTriedPaths(): array
+    {
+        return $this->triedPaths;
+    }
+}

src/Firebase/Factory.php

@@ -96,10 +96,7 @@ private function getServiceAccount(): ServiceAccount
         }
         // @codeCoverageIgnoreEnd
 
-        throw new LogicException(sprintf(
-            'No service account has been found. Please set the path to a service account credentials file with %s::%s()',
-            static::class, 'withCredentials($path)'
-        ));
+        throw new Firebase\Exception\CredentialsNotFound($this->credentialPaths);
     }
 
     private function getServiceAccountCandidates(): array