Plack::Test - Test PSGI applications with various backends


  use Plack::Test;
  use HTTP::Request::Common;

  # Simple OO interface
  my $app = sub { return [ 200, [], [ "Hello" ] ] };
  my $test = Plack::Test->create($app);

  my $res = $test->request(GET "/");
  is $res->content, "Hello";

  # traditional - named params
      app => sub {
          my $env = shift;
          return [ 200, [ 'Content-Type' => 'text/plain' ], [ "Hello World" ] ],
      client => sub {
          my $cb  = shift;
          my $req = HTTP::Request->new(GET => "http://localhost/hello");
          my $res = $cb->($req);
          like $res->content, qr/Hello World/;

  # positional params (app, client)
  my $app = sub { return [ 200, [], [ "Hello" ] ] };
  test_psgi $app, sub {
      my $cb  = shift;
      my $res = $cb->(GET "/");
      is $res->content, "Hello";


Plack::Test is a unified interface to test PSGI applications using HTTP::Request and HTTP::Response objects. It also allows you to run PSGI applications in various ways. The default backend is Plack::Test::MockHTTP, but you may also use any Plack::Handler implementation to run live HTTP requests against a web server.


  $test = Plack::Test->create($app, %options);

creates an instance of Plack::Test implementation class. $app has to be a valid PSGI application code reference.

  $res = $test->request($request);

takes an HTTP::Request object, runs it through the PSGI application to test and returns an HTTP::Response object.


Plack::Test also provides a functional interface that takes two callbacks, each of which represents PSGI application and HTTP client code that tests the application.

  test_psgi $app, $client;
  test_psgi app => $app, client => $client;

Runs the client test code $client against a PSGI application $app. The client callback gets one argument $cb, a callback that accepts an HTTP::Request object and returns an HTTP::Response object.

Use HTTP::Request::Common to import shortcuts for creating requests for GET, POST, DELETE, and PUT operations.

For your convenience, the HTTP::Request given to the callback automatically uses the HTTP protocol and the localhost ( by default), so the following code just works:

  use HTTP::Request::Common;
  test_psgi $app, sub {
      my $cb  = shift;
      my $res = $cb->(GET "/hello");

Note that however, it is not a good idea to pass an arbitrary (i.e. user-input) string to GET or even HTTP::Request->new by assuming that it always represents a path, because:

  my $req = GET "//foo/bar";

would represent a request for a URL that has no scheme, has a hostname foo and a path /bar, instead of a path //foo/bar which you might actually want.


Specify the Plack::Test backend using the environment variable PLACK_TEST_IMPL or $Plack::Test::Impl package variable.

The available values for the backend are:


(Default) Creates a PSGI env hash out of HTTP::Request object, runs the PSGI application in-process and returns HTTP::Response.


Runs one of Plack::Handler backends (Standalone by default) and sends live HTTP requests to test.


Runs tests against an external server specified in the PLACK_TEST_EXTERNALSERVER_URI environment variable instead of spawning the application in a server locally.

For instance, test your application with the HTTP::Server::ServerSimple server backend with:

  > env PLACK_TEST_IMPL=Server PLACK_SERVER=HTTP::Server::ServerSimple \
    prove -l t/test.t


Tatsuhiko Miyagawa