bug #17434 Improved the error message when a template is not found (rvanginneken, javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
----------

Improved the error message when a template is not found

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #14806
| License       | MIT
| Doc PR        | -

### Before

![template_error_before](https://cloud.githubusercontent.com/assets/73419/12414237/7db29212-be94-11e5-85b4-c6444aa853f8.png)

### After

![template_error_after](https://cloud.githubusercontent.com/assets/73419/12414242/80ed1eca-be94-11e5-992e-a0596a1e95ca.png)

This seems to work in the browser ... but I can't make tests pass. Could anybody please help me? Thanks!

Commits
-------

0134d76 Simplified everything
19bfa2e Added a test
88b913b Fixed the problem in an easier way
35f082f Fixed a syntax issue
968476b Improved the error message when a template is not found
e9d951a [CodingStandards] Conformed to coding standards
d3fe07b [TwigBundle] fixed Include file locations in "Template could not be found" exception

Author: fabpot

src/Symfony/Bundle/TwigBundle/Loader/FilesystemLoader.php

@@ -77,19 +77,18 @@ protected function findTemplate($template, $throw = true)
         try {
             $file = parent::findTemplate($logicalName);
         } catch (\Twig_Error_Loader $e) {
-            $previous = $e;
+            $twigLoaderException = $e;
 
             // for BC
             try {
                 $template = $this->parser->parse($template);
                 $file = $this->locator->locate($template);
             } catch (\Exception $e) {
-                $previous = $e;
             }
         }
 
         if (false === $file || null === $file) {
-            throw new \Twig_Error_Loader(sprintf('Unable to find template "%s".', $logicalName), -1, null, $previous);
+            throw $twigLoaderException;
         }
 
         return $this->cache[$logicalName] = $file;

src/Symfony/Bundle/TwigBundle/Tests/Loader/FilesystemLoaderTest.php

@@ -98,4 +98,21 @@ public function testTwigErrorIfLocatorReturnsFalse()
         $loader = new FilesystemLoader($locator, $parser);
         $loader->getCacheKey('name.format.engine');
     }
+
+    /**
+     * @expectedException \Twig_Error_Loader
+     * @expectedExceptionMessageRegExp /Unable to find template "name\.format\.engine" \(looked into: .*\/Tests\/Loader\/\.\.\/DependencyInjection\/Fixtures\/Resources\/views\)/
+     */
+    public function testTwigErrorIfTemplateDoesNotExist()
+    {
+        $parser = $this->getMock('Symfony\Component\Templating\TemplateNameParserInterface');
+        $locator = $this->getMock('Symfony\Component\Config\FileLocatorInterface');
+
+        $loader = new FilesystemLoader($locator, $parser);
+        $loader->addPath(__DIR__.'/../DependencyInjection/Fixtures/Resources/views');
+
+        $method = new \ReflectionMethod('Symfony\Bundle\TwigBundle\Loader\FilesystemLoader', 'findTemplate');
+        $method->setAccessible(true);
+        $method->invoke($loader, 'name.format.engine');
+    }
 }