'Error Handler' middleware

2 files changed, 140 insertions, 0 deletions

diff --git a/src/Router/Middleware/ErrorHandler.php b/src/Router/Middleware/ErrorHandler.php
new file mode 100644
index 0000000..789c455
--- /dev/null
+++ b/src/Router/Middleware/ErrorHandler.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace Jasny\Router\Middleware;
+
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * Handle error in following middlewares/app actions
+ */
+class ErrorHandler
+{    
+    /**
+     * Run middleware action
+     *
+     * @param ServerRequestInterface $request
+     * @param ResponseInterface      $response
+     * @param callback               $next
+     * @return ResponseInterface
+     */
+    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, $next = null)
+    {
+        if ($next && !is_callable($next)) {
+            throw new \InvalidArgumentException("'next' should be a callback");            
+        }
+
+        $error = false;
+
+        try {
+            $response = $next ? call_user_func($next, $request, $response) : $response;
+        } catch(\Throwable $e) {
+            $error = true;
+        } catch(\Exception $e) { #This block can be removed when migrating to PHP7, because Throwable represents both Exception and Error
+            $error = true;
+        }
+
+        return $error ? $this->handleError($response) : $response;
+    }
+
+    /**
+     * Handle caught error
+     *
+     * @param ResponseInterface $response
+     * @return ResponseInterface
+     */
+    protected function handleError($response)
+    {
+        $body = $response->getBody();        
+        $body->rewind();
+        $body->write('Unexpected error');
+
+        return $response->withStatus(500, 'Internal Server Error')->withBody($body);
+    }
+}
diff --git a/tests/Router/Middleware/ErrorHandlerTest.php b/tests/Router/Middleware/ErrorHandlerTest.php
new file mode 100644
index 0000000..c4b6313
--- /dev/null
+++ b/tests/Router/Middleware/ErrorHandlerTest.php
@@ -0,0 +1,86 @@
+<?php
+
+use Jasny\Router\Middleware\ErrorHandler;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
+
+class ErrorHandlerTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * Test invoke with invalid 'next' param
+     */
+    public function testInvokeInvalidNext()
+    {
+        $middleware = new ErrorHandler();
+        list($request, $response) = $this->getRequests();
+
+        $this->expectException(\InvalidArgumentException::class);
+
+        $result = $middleware($request, $response, 'not_callable');
+    }
+
+    /**
+     * Test that exception in 'next' callback is caught
+     */
+    public function testInvokeCatchError()
+    {
+        $middleware = new ErrorHandler();
+        list($request, $response) = $this->getRequests();
+
+        $this->expectCatchError($response);
+
+        $result = $middleware($request, $response, function($request, $response) {
+            throw new Exception('Test exception'); 
+        });
+
+        $this->assertEquals(get_class($response), get_class($result), "Middleware should return response object");        
+    }
+
+    /**
+     * Test case when there is no error
+     */
+    public function testInvokeNoError()
+    {
+        $middleware = new ErrorHandler();
+        list($request, $response) = $this->getRequests();
+
+        $result = $middleware($request, $response, function($request, $response) {
+            $response->nextCalled = true;
+
+            return $response;
+        });        
+
+        $this->assertEquals(get_class($response), get_class($result), "Middleware should return response object");        
+        $this->assertTrue($result->nextCalled, "'next' was not called");   
+    }
+
+    /**
+     * Get requests for testing
+     *
+     * @return array
+     */
+    public function getRequests()
+    {
+        $request = $this->createMock(ServerRequestInterface::class);
+        $response = $this->createMock(ResponseInterface::class);
+
+        return [$request, $response];
+    }
+
+    /**
+     * Expect for error
+     *
+     * @param ResponseInterface $response 
+     */
+    public function expectCatchError($response)
+    {
+        $stream = $this->createMock(StreamInterface::class);
+        $stream->expects($this->once())->method('rewind');
+        $stream->expects($this->once())->method('write')->with($this->equalTo('Unexpected error'));
+
+        $response->method('getBody')->will($this->returnValue($stream));
+        $response->expects($this->once())->method('withBody')->with($this->equalTo($stream))->will($this->returnSelf());
+        $response->expects($this->once())->method('withStatus')->with($this->equalTo(500), $this->equalTo('Internal Server Error'))->will($this->returnSelf());
+    }
+}