Finish path identification - configurability & exception handling

src/Exceptions/RouteIsMissingTenantParameterException.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Stancl\Tenancy\Exceptions;
+
+use Exception;
+use Stancl\Tenancy\Resolvers\PathTenantResolver;
+
+class RouteIsMissingTenantParameterException extends Exception
+{
+    public function __construct()
+    {
+        $parameter = PathTenantResolver::$tenantParameterName;
+
+        parent::__construct("The route's first argument is not the tenant id (configured paramter name: $parameter).");
+    }
+}

src/Middleware/InitializeTenancyByPath.php

@@ -5,6 +5,7 @@ namespace Stancl\Tenancy\Middleware;
 use Closure;
 use Illuminate\Http\Request;
 use Illuminate\Routing\Route;
+use Stancl\Tenancy\Exceptions\RouteIsMissingTenantParameterException;
 use Stancl\Tenancy\Resolvers\PathTenantResolver;
 use Stancl\Tenancy\Tenancy;
 
@@ -27,15 +28,16 @@ class InitializeTenancyByPath extends IdentificationMiddleware
         /** @var Route $route */
         $route = $request->route();
 
-        // todo test the behavior described by the comment
         // Only initialize tenancy if tenant is the first parameter
         // We don't want to initialize tenancy if the tenant is
         // simply injected into some route controller action.
-        if ($route->parameterNames()[0] === 'tenant') {
+        if ($route->parameterNames()[0] === PathTenantResolver::$tenantParameterName) {
             return $this->initializeTenancy(
                 $request, $next, $route
             );
-        } // todo else case should probably throw exception about malformed route? or do we just leave that as the developer's responsibility?
+        } else {
+            throw new RouteIsMissingTenantParameterException;
+        }
 
         return $next($request);
     }

src/Resolvers/PathTenantResolver.php

@@ -9,13 +9,15 @@ use Stancl\Tenancy\Exceptions\TenantCouldNotBeIdentifiedByPathException;
 
 class PathTenantResolver implements TenantResolver
 {
+    public static $tenantParameterName = 'tenant';
+
     public function resolve(...$args): Tenant
     {
         /** @var Route $route */
         $route = $args[0];
 
-        if ($id = $route->parameter('tenant')) {
-            $route->forgetParameter('tenant');
+        if ($id = $route->parameter(static::$tenantParameterName)) {
+            $route->forgetParameter(static::$tenantParameterName);
             
             if ($tenant = config('tenancy.tenant_model')::find($id)) {
                 return $tenant;