Allow omitting method return type

Support for `@method myMethod()` was missing but according to the
docs of phpdocumentor this is possible.

src/DocBlock/Tags/Method.php

@@ -125,6 +125,11 @@ final class Method extends BaseTag implements Factory\StaticMethod
         list(, $static, $returnType, $methodName, $arguments, $description) = $matches;
 
         $static      = $static === 'static';
+
+        if ($returnType === '') {
+            $returnType = 'void';
+        }
+
         $returnType  = $typeResolver->resolve($returnType, $context);
         $description = $descriptionFactory->create($description, $context);
 
@@ -196,11 +201,11 @@ final class Method extends BaseTag implements Factory\StaticMethod
             $arguments[] = $argument['type'] . ' $' . $argument['name'];
         }
 
-        return ($this->isStatic() ? 'static ' : '')
+        return trim(($this->isStatic() ? 'static ' : '')
             . (string)$this->returnType . ' '
             . $this->methodName
             . '(' . implode(', ', $arguments) . ')'
-            . ($this->description ? ' ' . $this->description->render() : '');
+            . ($this->description ? ' ' . $this->description->render() : ''));
     }
 
     private function filterArguments($arguments)

tests/unit/DocBlock/Tags/MethodTest.php

@@ -468,4 +468,28 @@ class MethodTest extends \PHPUnit_Framework_TestCase
         $this->assertInstanceOf(Void_::class, $fixture->getReturnType());
         $this->assertSame($description, $fixture->getDescription());
     }
+
+    public function testCreateWithoutReturnType()
+    {
+        $descriptionFactory = m::mock(DescriptionFactory::class);
+        $resolver           = new TypeResolver();
+        $context            = new Context('');
+
+        $description  = new Description('');
+
+        $descriptionFactory->shouldReceive('create')->with('', $context)->andReturn($description);
+
+        $fixture = Method::create(
+            'myMethod()',
+            $resolver,
+            $descriptionFactory,
+            $context
+        );
+
+        $this->assertSame('void myMethod()', (string)$fixture);
+        $this->assertSame('myMethod', $fixture->getMethodName());
+        $this->assertEquals([], $fixture->getArguments());
+        $this->assertInstanceOf(Void_::class, $fixture->getReturnType());
+        $this->assertSame($description, $fixture->getDescription());
+    }
 }