Merge route result params with those provided

If the following conditions are met:

- the provided `$params` are an array
- the route result is not a failure
- the route result represents the same route as requested

then the helper merges the route result params, if any, with those
provided at invocation, with the latter taking precedence.

Author: weierophinney

src/UrlHelper.php

@@ -55,6 +55,10 @@ public function __invoke($route = null, $params = [])
             return $this->generateUriFromResult($params);
         }
 
+        if ($this->result) {
+            $params = $this->mergeParams($route, $params);
+        }
+
         return $this->router->generateUri($route, $params);
     }
 
@@ -84,4 +88,39 @@ private function generateUriFromResult(array $params)
         $params = array_merge($this->result->getMatchedParams(), $params);
         return $this->router->generateUri($name, $params);
     }
+
+    /**
+     * Merge route result params and provided parameters.
+     *
+     * If $params is not an array, returns them verbatim.
+     *
+     * If the route result represents a routing failure, returns the params
+     * verbatim.
+     *
+     * If the route result does not represent the same route name requested,
+     * returns the params verbatim.
+     *
+     * Otherwise, merges the route result params with those provided at
+     * invocation, with the latter having precedence.
+     *
+     * @param string $route Route name.
+     * @param array $params Parameters provided at invocation.
+     * @return array
+     */
+    private function mergeParams($route, $params)
+    {
+        if (! is_array($params)) {
+            return $params;
+        }
+
+        if ($this->result->isFailure()) {
+            return $params;
+        }
+
+        if ($this->result->getMatchedRouteName() !== $route) {
+            return $params;
+        }
+
+        return array_merge($this->result->getMatchedParams(), $params);
+    }
 }

test/UrlHelperTest.php

@@ -89,4 +89,49 @@ public function testWhenRouteProvidedTheHelperDelegatesToTheRouterToGenerateUrl(
         $helper = $this->createHelper();
         $this->assertEquals('URL', $helper('foo', ['bar' => 'baz']));
     }
+
+    public function testIfRouteResultRouteNameDoesNotMatchRequestedNameItWillNotMergeParamsToGenerateUri()
+    {
+        $result = $this->prophesize(RouteResult::class);
+        $result->isFailure()->willReturn(false);
+        $result->getMatchedRouteName()->willReturn('not-resource');
+        $result->getMatchedParams()->shouldNotBeCalled();
+
+        $this->router->generateUri('resource', [])->willReturn('URL');
+
+        $helper = $this->createHelper();
+        $helper->setRouteResult($result->reveal());
+
+        $this->assertEquals('URL', $helper('resource'));
+    }
+
+    public function testMergesRouteResultParamsWithProvidedParametersToGenerateUri()
+    {
+        $result = $this->prophesize(RouteResult::class);
+        $result->isFailure()->willReturn(false);
+        $result->getMatchedRouteName()->willReturn('resource');
+        $result->getMatchedParams()->willReturn(['id' => 1]);
+
+        $this->router->generateUri('resource', ['id' => 1, 'version' => 2])->willReturn('URL');
+
+        $helper = $this->createHelper();
+        $helper->setRouteResult($result->reveal());
+
+        $this->assertEquals('URL', $helper('resource', ['version' => 2]));
+    }
+
+    public function testProvidedParametersOverrideAnyPresentInARouteResultWhenGeneratingUri()
+    {
+        $result = $this->prophesize(RouteResult::class);
+        $result->isFailure()->willReturn(false);
+        $result->getMatchedRouteName()->willReturn('resource');
+        $result->getMatchedParams()->willReturn(['id' => 1]);
+
+        $this->router->generateUri('resource', ['id' => 2])->willReturn('URL');
+
+        $helper = $this->createHelper();
+        $helper->setRouteResult($result->reveal());
+
+        $this->assertEquals('URL', $helper('resource', ['id' => 2]));
+    }
 }