Add error handeling pages (primarily for 404)

Now you can add special error pages for http error codes.
Currently it works only for 404 errors. If a route is called, which
isn't defined, the framwork gave our a generic 404 error page.
Now you can redirect this error to a controller, which allowes you to
create a special error handling for that case yourself.
you just need to add a route "404 => MyErrorController" to your routing
list. If it's not defined, noting will change and the old error message
will be returned as beforehand.

2 files changed, 36 insertions, 2 deletions

diff --git a/lib/zero/router.rb b/lib/zero/router.rb
index 7f16933..0d3859a 100644
--- a/lib/zero/router.rb
+++ b/lib/zero/router.rb
@@ -16,6 +16,14 @@ module Zero
   #   router = Zero::Router.new(
   #     '/foo/:id' => FooController
   #   )
+  #
+  #  # @example of a simple router
+  #  #  which supports an extra controller for a 404 error page
+  #   router = Zero::Router.new(
+  #     '/' => WelcomeController,
+  #     404 => NotFoundController
+  #   )
+  #
   class Router
     # match for variables in routes
     VARIABLE_MATCH = %r{:(\w+)[^/]?}
@@ -41,7 +49,14 @@ module Zero
     # @param routes [Hash] a map of URLs to rack compatible applications
     def initialize(routes)
       @routes = {}
-      routes.to_a.sort_by(&:first).reverse.each do |route, target|
+
+      routes.to_a.sort_by{|x| x[0].to_s}.reverse.each do |route, target|
+        # Support for special error handling
+        if route.is_a? Integer
+          @routes[route] = target
+          next
+        end
+
         @routes[
           Regexp.new(REGEX_BEGINNING +
                      route.gsub(VARIABLE_MATCH, VARIABLE_REGEX) +
@@ -58,6 +73,9 @@ module Zero
     def call(env)
       env[ENV_KEY_CUSTOM] ||= {}
       @routes.each do |route, target|
+        # Skip all routes, which keys are Integers
+        next if route.is_a? Integer
+
         match = route.match(env[ENV_KEY_PATH_INFO])
         if match
           match.names.each_index do |i|
@@ -66,6 +84,10 @@ module Zero
           return target.call(env)
         end
       end
+      # If no route is found, we call the target 404 error route, if it's set
+      return @routes[404].call(env) unless @routes[404].nil?
+
+      # If no target for the 404 error is set, we return a default message
       [404, {'Content-Type' => 'text/html'}, ['Not found!']]
     end
   end
diff --git a/spec/unit/zero/router/call_spec.rb b/spec/unit/zero/router/call_spec.rb
index 835d51d..dabf664 100644
--- a/spec/unit/zero/router/call_spec.rb
+++ b/spec/unit/zero/router/call_spec.rb
@@ -9,6 +9,10 @@ describe Zero::Router, '#call' do
   let(:wrong_app) do
     lambda {|env| [200, {'Content-Type' => 'text/html'}, 'Wrong'] }
   end
+
+  let(:not_found_app) do
+    lambda {|env| [404, {'Content-Type' => 'text/html'}, ['Wrong way!']] }
+  end
   let(:app) { SpecApp }
 
   shared_examples_for 'a sample app' do
@@ -39,7 +43,7 @@ describe Zero::Router, '#call' do
   end
 
   context 'with nested routes' do
-    let(:routes) {{ '/' => wrong_app, '/foo' => app, '/foo/bar' => wrong_app }}
+    let(:routes) {{ '/foo/bar' => wrong_app, '/foo' => app, '/' => wrong_app }}
     let(:env) { EnvGenerator.get('/foo') }
     it_behaves_like "a sample app"
   end
@@ -76,6 +80,14 @@ describe Zero::Router, '#call' do
     it_behaves_like "a sample app"
   end
 
+  context 'with a route not found, but 404 error route set' do
+    let(:routes) {{ '/foo/bar/baz' => app, 404 => not_found_app }}
+    let(:env) { EnvGenerator.get('/foo/bar') }
+    let(:result) { ['Wrong way!'] }
+    let(:status_code) { 404 }
+    it_behaves_like "a sample app"
+  end
+
   context 'with parameters' do
     let(:routes) {{ '/foo/:id' => app }}
     let(:env) { EnvGenerator.get('/foo/bar') }