use an abbreviated session definition syntax (borrowing further from Capistrano)

7 files changed, 137 insertions, 95 deletions

diff --git a/README.rdoc b/README.rdoc
index 3a90d57..d80580b 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -24,13 +24,13 @@ In a nutshell:
     session.via 'gateway', 'gateway-user'
 
     # define the servers we want to use
-    session.use 'host1', 'user1'
-    session.use 'host2', 'user2'
+    session.use 'user1@host1'
+    session.use 'user2@host2'
 
     # define servers in groups for more granular access
     session.group :app do
-      session.use 'app1', 'user'
-      session.use 'app2', 'user'
+      session.use 'user@app1'
+      session.use 'user@app2'
     end
 
     # execute commands on all servers
diff --git a/lib/net/ssh/multi.rb b/lib/net/ssh/multi.rb
index 8f393df..1664d0e 100644
--- a/lib/net/ssh/multi.rb
+++ b/lib/net/ssh/multi.rb
@@ -19,13 +19,13 @@ module Net; module SSH
   #     session.via 'gateway', 'gateway-user'
   # 
   #     # define the servers we want to use
-  #     session.use 'host1', 'user1'
-  #     session.use 'host2', 'user2'
+  #     session.use 'user1@host1'
+  #     session.use 'user2@host2'
   # 
   #     # define servers in groups for more granular access
   #     session.group :app do
-  #       session.use 'app1', 'user'
-  #       session.use 'app2', 'user'
+  #       session.use 'user@app1'
+  #       session.use 'user@app2'
   #     end
   # 
   #     # execute commands on all servers
diff --git a/lib/net/ssh/multi/server.rb b/lib/net/ssh/multi/server.rb
index 3354b0a..a9d01aa 100644
--- a/lib/net/ssh/multi/server.rb
+++ b/lib/net/ssh/multi/server.rb
@@ -6,13 +6,15 @@ module Net; module SSH; module Multi
   # need to instantiate one of these directly: instead, you should use
   # Net::SSH::Multi::Session#use.
   class Server
+    include Comparable
+
     # The Net::SSH::Multi::Session instance that manages this server instance.
     attr_reader :master
 
     # The host name (or IP address) of the server to connect to.
     attr_reader :host
 
-    # The user name to use when connecting to this server.
+    # The user name to use when logging into the server.
     attr_reader :user
 
     # The Hash of additional options to pass to Net::SSH when connecting
@@ -26,15 +28,31 @@ module Net; module SSH; module Multi
     # Creates a new Server instance with the given connection information. The
     # +master+ argument must be a reference to the Net::SSH::Multi::Session
     # instance that will manage this server reference. The +options+ hash must
-    # conform to the options described for Net::SSH::start, with one addition:
+    # conform to the options described for Net::SSH::start, with two additions:
     #
     # * :via => a Net::SSH::Gateway instance to use when establishing a
     #   connection to this server.
-    def initialize(master, host, user, options={})
+    # * :user => the name of the user to use when logging into this server.
+    #
+    # The +host+ argument may include the username and port number, in which
+    # case those values take precedence over similar values given in the +options+:
+    #
+    #   server = Net::SSH::Multi::Server.new(session, 'user@host:1234')
+    #   puts server.user #-> user
+    #   puts server.port #-> 1234
+    def initialize(master, host, options={})
       @master = master
-      @host = host
-      @user = user
       @options = options.dup
+
+      @user, @host, port = host.match(/^(?:([^;,:=]+)@|)(.*?)(?::(\d+)|)$/)[1,3]
+
+      user_opt, port_opt = @options.delete(:user), @options.delete(:port)
+
+      @user = @user || user_opt || master.default_user
+      port ||= port_opt
+
+      @options[:port] = port.to_i if port
+
       @gateway = @options.delete(:via)
       @failed = false
     end
@@ -51,15 +69,12 @@ module Net; module SSH; module Multi
       options[:port] || 22
     end
 
-    # Compares the given +server+ to this instance, and returns true if they
-    # have the same host, user, and port.
-    def eql?(server)
-      host == server.host &&
-      user == server.user &&
-      port == server.port
+    # Gives server definitions a sort order, and allows comparison.
+    def <=>(server)
+      [host, port, user] <=> [server.host, server.port, server.user]
     end
 
-    alias :== :eql?
+    alias :eql? :==
 
     # Generates a +Fixnum+ hash value for this object. This function has the
     # property that +a.eql?(b)+ implies +a.hash == b.hash+. The
diff --git a/lib/net/ssh/multi/session.rb b/lib/net/ssh/multi/session.rb
index 4c6e1a0..c7462d6 100644
--- a/lib/net/ssh/multi/session.rb
+++ b/lib/net/ssh/multi/session.rb
@@ -20,13 +20,13 @@ module Net; module SSH; module Multi
   #     session.via 'gateway', 'gateway-user'
   # 
   #     # define the servers we want to use
-  #     session.use 'host1', 'user1'
-  #     session.use 'host2', 'user2'
+  #     session.use 'user1@host1'
+  #     session.use 'user2@host2'
   # 
   #     # define servers in groups for more granular access
   #     session.group :app do
-  #       session.use 'app1', 'user'
-  #       session.use 'app2', 'user'
+  #       session.use 'user@app1'
+  #       session.use 'user@app2'
   #     end
   # 
   #     # execute commands on all servers
@@ -65,6 +65,12 @@ module Net; module SSH; module Multi
     # :warn if connection errors should cause a warning.
     attr_accessor :on_error
 
+    # The default user name to use when connecting to a server. If a user name
+    # is not given for a particular server, this value will be used. It defaults
+    # to ENV['USER'] || ENV['USERNAME'], or "unknown" if neither of those are
+    # set.
+    attr_accessor :default_user
+
     # The number of connections that are currently open.
     attr_reader :open_connections #:nodoc:
 
@@ -92,6 +98,7 @@ module Net; module SSH; module Multi
       @open_groups = []
       @connect_threads = []
       @on_error = :fail
+      @default_user = ENV['USER'] || ENV['USERNAME'] || "unknown"
 
       @open_connections = 0
       @pending_sessions = []
@@ -171,11 +178,11 @@ module Net; module SSH; module Multi
     # a different Net::SSH::Gateway instance (or +nil+) with the :via key in
     # the +options+.
     #
-    #   session.use 'host', 'user'
-    #   session.use 'host2', 'user2', :via => nil
-    #   session.use 'host3', 'user3', :via => Net::SSH::Gateway.new('gateway.host', 'user')
-    def use(host, user, options={})
-      server = Server.new(self, host, user, {:via => default_gateway}.merge(options))
+    #   session.use 'host'
+    #   session.use 'user@host2', :via => nil
+    #   session.use 'host3', :user => "user3", :via => Net::SSH::Gateway.new('gateway.host', 'user')
+    def use(host, options={})
+      server = Server.new(self, host, {:via => default_gateway}.merge(options))
       exists = servers.index(server)
       if exists
         server = servers[exists]
diff --git a/test/server_test.rb b/test/server_test.rb
index caca334..02ba0e0 100644
--- a/test/server_test.rb
+++ b/test/server_test.rb
@@ -3,80 +3,96 @@ require 'net/ssh/multi/server'
 
 class ServerTest < Test::Unit::TestCase
   def setup
-    @master = mock('multi-session')
+    @master = stub('multi-session', :default_user => "bob")
   end
 
   def test_accessor_without_properties_should_access_empty_hash
-    assert_nil server('host', 'user')[:foo]
+    assert_nil server('host')[:foo]
   end
 
   def test_accessor_with_properties_should_access_properties
-    assert_equal "hello", server('host', 'user', :properties => { :foo => "hello" })[:foo]
+    assert_equal "hello", server('host', :properties => { :foo => "hello" })[:foo]
   end
 
   def test_port_should_return_22_by_default
-    assert_equal 22, server('host', 'user').port
+    assert_equal 22, server('host').port
   end
 
   def test_port_should_return_given_port_when_present
-    assert_equal 1234, server('host', 'user', :port => 1234).port
+    assert_equal 1234, server('host', :port => 1234).port
+  end
+
+  def test_port_should_return_parsed_port_when_present
+    assert_equal 1234, server('host:1234', :port => 1235).port
+  end
+
+  def test_user_should_return_default_user_by_default
+    assert_equal "bob", server('host').user
+  end
+
+  def test_user_should_return_given_user_when_present
+    assert_equal "jim", server('host', :user => "jim").user
+  end
+
+  def test_user_should_return_parsed_user_when_present
+    assert_equal "jim", server('jim@host', :user => "john").user
   end
 
   def test_equivalence_when_host_and_user_and_port_match
-    s1 = server('host', 'user', :port => 1234)
-    s2 = server('host', 'user', :port => 1234)
+    s1 = server('user@host:1234')
+    s2 = server('user@host:1234')
     assert s1.eql?(s2)
     assert_equal s1.hash, s2.hash
     assert s1 == s2
   end
 
   def test_equivalence_when_host_mismatch
-    s1 = server('host1', 'user', :port => 1234)
-    s2 = server('host2', 'user', :port => 1234)
+    s1 = server('user@host1:1234')
+    s2 = server('user@host2:1234')
     assert !s1.eql?(s2)
     assert_not_equal s1.hash, s2.hash
     assert s1 != s2
   end
 
   def test_equivalence_when_port_mismatch
-    s1 = server('host', 'user', :port => 1234)
-    s2 = server('host', 'user', :port => 1235)
+    s1 = server('user@host:1234')
+    s2 = server('user@host:1235')
     assert !s1.eql?(s2)
     assert_not_equal s1.hash, s2.hash
     assert s1 != s2
   end
 
   def test_equivalence_when_user_mismatch
-    s1 = server('host', 'user1', :port => 1234)
-    s2 = server('host', 'user2', :port => 1234)
+    s1 = server('user1@host:1234')
+    s2 = server('user2@host:1234')
     assert !s1.eql?(s2)
     assert_not_equal s1.hash, s2.hash
     assert s1 != s2
   end
 
   def test_to_s_should_include_user_and_host
-    assert_equal "user@host", server('host', 'user').to_s
+    assert_equal "user@host", server('user@host').to_s
   end
 
   def test_to_s_should_include_user_and_host_and_port_when_port_is_given
-    assert_equal "user@host:1234", server('host', 'user', :port => 1234).to_s
+    assert_equal "user@host:1234", server('user@host:1234').to_s
   end
 
   def test_gateway_should_be_nil_by_default
-    assert_nil server('host', 'user').gateway
+    assert_nil server('host').gateway
   end
 
   def test_gateway_should_be_set_with_the_via_value
     gateway = mock('gateway')
-    assert_equal gateway, server('host', 'user', :via => gateway).gateway
+    assert_equal gateway, server('host', :via => gateway).gateway
   end
 
   def test_session_with_default_argument_should_not_instantiate_session
-    assert_nil server('host', 'user').session
+    assert_nil server('host').session
   end
 
   def test_session_with_true_argument_should_instantiate_and_cache_session
-    srv = server('host', 'user', :port => 1234)
+    srv = server('host')
     session = expect_connection_to(srv)
     assert_equal session, srv.session(true)
     assert_equal session, srv.session(true)
@@ -84,23 +100,23 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_session_that_cannot_authenticate_adds_host_to_exception_message
-    srv = server('host', 'user')
-    Net::SSH.expects(:start).with('host', 'user', {}).raises(Net::SSH::AuthenticationFailed.new('user'))
+    srv = server('host')
+    Net::SSH.expects(:start).with('host', 'bob', {}).raises(Net::SSH::AuthenticationFailed.new('bob'))
 
     begin
       srv.new_session
       flunk
     rescue Net::SSH::AuthenticationFailed => e
-      assert_equal "user@host", e.message
+      assert_equal "bob@host", e.message
     end
   end
 
   def test_close_channels_when_session_is_not_open_should_not_do_anything
-    assert_nothing_raised { server('host', 'user').close_channels }
+    assert_nothing_raised { server('host').close_channels }
   end
 
   def test_close_channels_when_session_is_open_should_iterate_over_open_channels_and_close_them
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     c1 = mock('channel', :close => nil)
     c2 = mock('channel', :close => nil)
@@ -111,11 +127,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_close_when_session_is_not_open_should_not_do_anything
-    assert_nothing_raised { server('host', 'user').close }
+    assert_nothing_raised { server('host').close }
   end
 
   def test_close_when_session_is_open_should_close_session
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:close)
     @master.expects(:server_closed).with(srv)
@@ -124,11 +140,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_busy_should_be_false_when_session_is_not_open
-    assert !server('host', 'user').busy?
+    assert !server('host').busy?
   end
 
   def test_busy_should_be_false_when_session_is_not_busy
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:busy?).returns(false)
     srv.session(true)
@@ -136,7 +152,7 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_busy_should_be_true_when_session_is_busy
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:busy?).returns(true)
     srv.session(true)
@@ -144,11 +160,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_preprocess_should_be_nil_when_session_is_not_open
-    assert_nil server('host', 'user').preprocess
+    assert_nil server('host').preprocess
   end
 
   def test_preprocess_should_return_result_of_session_preprocess
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:preprocess).returns(:result)
     srv.session(true)
@@ -156,11 +172,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_readers_should_return_empty_array_when_session_is_not_open
-    assert_equal [], server('host', 'user').readers
+    assert_equal [], server('host').readers
   end
 
   def test_readers_should_return_all_listeners_when_session_is_open
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:listeners).returns(1 => 2, 3 => 4, 5 => 6, 7 => 8)
     srv.session(true)
@@ -168,11 +184,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_writers_should_return_empty_array_when_session_is_not_open
-    assert_equal [], server('host', 'user').writers
+    assert_equal [], server('host').writers
   end
 
   def test_writers_should_return_all_listeners_that_are_pending_writes_when_session_is_open
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     listeners = { writer(:ready) => 1, writer(:reader) => 2,
       writer(:reader) => 3, writer(:idle) => 4, writer(:ready) => 5 }
@@ -182,11 +198,11 @@ class ServerTest < Test::Unit::TestCase
   end
 
   def test_postprocess_should_return_true_when_session_is_not_open
-    assert_equal true, server('host', 'user').postprocess([], [])
+    assert_equal true, server('host').postprocess([], [])
   end
 
   def test_postprocess_should_call_session_postprocess_with_ios_belonging_to_session
-    srv = server('host', 'user')
+    srv = server('host')
     session = expect_connection_to(srv)
     session.expects(:listeners).returns(1 => 2, 3 => 4, 5 => 6, 7 => 8)
     session.expects(:postprocess).with([1,3], [7]).returns(:result)
@@ -196,8 +212,8 @@ class ServerTest < Test::Unit::TestCase
 
   private
 
-    def server(host, user, options={})
-      Net::SSH::Multi::Server.new(@master, host, user, options)
+    def server(host, options={})
+      Net::SSH::Multi::Server.new(@master, host, options)
     end
 
     def expect_connection_to(server)
diff --git a/test/session_actions_test.rb b/test/session_actions_test.rb
index c4f3e58..6c688af 100644
--- a/test/session_actions_test.rb
+++ b/test/session_actions_test.rb
@@ -12,8 +12,12 @@ class SessionActionsTest < Test::Unit::TestCase
       @servers = []
     end
 
-    def use(h, u, o={})
-      server = Net::SSH::Multi::Server.new(self, h, u, o)
+    def default_user
+      "user"
+    end
+
+    def use(h, o={})
+      server = Net::SSH::Multi::Server.new(self, h, o)
       servers << server
       server
     end
@@ -24,7 +28,7 @@ class SessionActionsTest < Test::Unit::TestCase
   end
 
   def test_busy_should_be_true_if_any_server_is_busy
-    srv1, srv2, srv3 = @session.use('h1', 'u1'), @session.use('h2', 'u2'), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
     srv1.stubs(:busy?).returns(false)
     srv2.stubs(:busy?).returns(false)
     srv3.stubs(:busy?).returns(true)
@@ -32,7 +36,7 @@ class SessionActionsTest < Test::Unit::TestCase
   end
 
   def test_busy_should_be_false_if_all_servers_are_not_busy
-    srv1, srv2, srv3 = @session.use('h1', 'u1', :properties => {:a => 1}), @session.use('h2', 'u2', :properties => {:a => 1, :b => 2}), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
     srv1.stubs(:busy?).returns(false)
     srv2.stubs(:busy?).returns(false)
     srv3.stubs(:busy?).returns(false)
@@ -51,8 +55,8 @@ class SessionActionsTest < Test::Unit::TestCase
   end
 
   def test_open_channel_should_delegate_to_sessions_and_set_accessors_on_each_channel_and_return_multi_channel
-    srv1 = @session.use('h1', 'u1')
-    srv2 = @session.use('h2', 'u2')
+    srv1 = @session.use('h1')
+    srv2 = @session.use('h2')
     s1 = { :server => srv1 }
     s2 = { :server => srv2 }
     c1 = { :stub => :value }
diff --git a/test/session_test.rb b/test/session_test.rb
index 288275a..6446ace 100644
--- a/test/session_test.rb
+++ b/test/session_test.rb
@@ -44,7 +44,7 @@ class SessionTest < Test::Unit::TestCase
 
   def test_use_should_add_new_server_to_server_list
     @session.open_groups.concat([:first, :second])
-    server = @session.use('host', 'user', :a => :b)
+    server = @session.use('user@host', :a => :b)
     assert_equal [server], @session.servers
     assert_equal 'host', server.host
     assert_equal 'user', server.user
@@ -54,7 +54,7 @@ class SessionTest < Test::Unit::TestCase
 
   def test_use_with_open_groups_should_add_new_server_to_server_list_and_groups
     @session.open_groups.concat([:first, :second])
-    server = @session.use('host', 'user')
+    server = @session.use('host')
     assert_equal [server], @session.groups[:first]
     assert_equal [server], @session.groups[:second]
   end
@@ -62,13 +62,13 @@ class SessionTest < Test::Unit::TestCase
   def test_use_with_default_gateway_should_set_gateway_on_server
     Net::SSH::Gateway.expects(:new).with('host', 'user', {}).returns(:gateway)
     @session.via('host', 'user')
-    server = @session.use('host2', 'user2')
+    server = @session.use('host2')
     assert_equal :gateway, server.gateway
   end
 
   def test_use_with_duplicate_server_will_not_add_server_twice
-    s1 = @session.use('host', 'user')
-    s2 = @session.use('host', 'user')
+    s1 = @session.use('host')
+    s2 = @session.use('host')
     assert_equal 1, @session.servers.length
     assert_equal s1.object_id, s2.object_id
   end
@@ -96,14 +96,14 @@ class SessionTest < Test::Unit::TestCase
   end
 
   def test_on_should_return_subsession_containing_only_the_given_servers
-    s1 = @session.use('h1', 'u1')
-    s2 = @session.use('h2', 'u2')
+    s1 = @session.use('h1')
+    s2 = @session.use('h2')
     subsession = @session.on(s1, s2)
     assert_equal [s1, s2], subsession.servers
   end
 
   def test_on_should_yield_subsession_if_block_is_given
-    s1 = @session.use('h1', 'u1')
+    s1 = @session.use('h1')
     yielded = nil
     result = @session.on(s1) do |s|
       yielded = s
@@ -113,30 +113,30 @@ class SessionTest < Test::Unit::TestCase
   end
 
   def test_servers_for_should_return_all_servers_if_no_arguments
-    srv1, srv2, srv3 = @session.use('h1', 'u1'), @session.use('h2', 'u2'), @session.use('h3', 'u3')
-    assert_equal %w(h1 h2 h3), @session.servers_for.map { |s| s.host }.sort
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
+    assert_equal [srv1, srv2, srv3], @session.servers_for.sort
   end
 
   def test_servers_for_should_return_servers_only_for_given_group
-    srv1, srv2, srv3 = @session.use('h1', 'u1'), @session.use('h2', 'u2'), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
     @session.group :app => [srv1, srv2], :db => [srv3]
-    assert_equal %w(h1 h2), @session.servers_for(:app).map { |s| s.host }.sort
+    assert_equal [srv1, srv2], @session.servers_for(:app).sort
   end
 
   def test_servers_for_should_not_return_duplicate_servers
-    srv1, srv2, srv3 = @session.use('h1', 'u1'), @session.use('h2', 'u2'), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
     @session.group :app => [srv1, srv2], :db => [srv2, srv3]
-    assert_equal ["h1", "h2", "h3"], @session.servers_for(:app, :db).map { |s| s.host }.sort
+    assert_equal [srv1, srv2, srv3], @session.servers_for(:app, :db).sort
   end
 
   def test_servers_for_should_correctly_apply_only_and_except_constraints
-    srv1, srv2, srv3 = @session.use('h1', 'u1', :properties => {:a => 1}), @session.use('h2', 'u2', :properties => {:a => 1, :b => 2}), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1', :properties => {:a => 1}), @session.use('h2', :properties => {:a => 1, :b => 2}), @session.use('h3')
     @session.group :app => [srv1, srv2, srv3]
     assert_equal [srv1], @session.servers_for(:app => {:only => {:a => 1}, :except => {:b => 2}})
   end
 
   def test_close_should_close_server_sessions
-    srv1, srv2 = @session.use('h1', 'u1'), @session.use('h2', 'u2')
+    srv1, srv2 = @session.use('h1'), @session.use('h2')
     srv1.expects(:close_channels)
     srv2.expects(:close_channels)
     srv1.expects(:close)
@@ -160,25 +160,25 @@ class SessionTest < Test::Unit::TestCase
   end
 
   def test_preprocess_should_immediately_return_false_if_block_returns_false
-    srv = @session.use('h1', 'u1')
+    srv = @session.use('h1')
     srv.expects(:preprocess).never
     assert_equal false, @session.preprocess { false }
   end
 
   def test_preprocess_should_call_preprocess_on_component_servers
-    srv = @session.use('h1', 'u1')
+    srv = @session.use('h1')
     srv.expects(:preprocess)
     assert_equal :hello, @session.preprocess { :hello }
   end
 
   def test_preprocess_should_succeed_even_without_block
-    srv = @session.use('h1', 'u1')
+    srv = @session.use('h1')
     srv.expects(:preprocess)
     assert_equal true, @session.preprocess
   end
 
   def test_postprocess_should_call_postprocess_on_component_servers
-    srv = @session.use('h1', 'u1')
+    srv = @session.use('h1')
     srv.expects(:postprocess).with([:a], [:b])
     assert_equal true, @session.postprocess([:a], [:b])
   end
@@ -189,7 +189,7 @@ class SessionTest < Test::Unit::TestCase
 
   def test_process_should_call_select_on_combined_readers_and_writers_from_all_servers
     @session.expects(:postprocess).with([:b, :c], [:a, :c])
-    srv1, srv2, srv3 = @session.use('h1', 'u1'), @session.use('h2', 'u2'), @session.use('h3', 'u3')
+    srv1, srv2, srv3 = @session.use('h1'), @session.use('h2'), @session.use('h3')
     srv1.expects(:readers).returns([:a])
     srv1.expects(:writers).returns([:a])
     srv2.expects(:readers).returns([])