fix 'filter' variable so it works as documented

The variable ':filter' is documented as requiring the keys 'hosts' and
'roles' to set Host and Role filters. In actual fact it uses 'host' and
'role'. This commit adds support and tests for both.

Fixes #1457

lib/capistrano/configuration.rb

@@ -100,6 +100,8 @@ module Capistrano
       @filters << Filter.new(:role, ENV['ROLES']) if ENV['ROLES']
       @filters << Filter.new(:host, ENV['HOSTS']) if ENV['HOSTS']
       fh = fetch_for(:filter,{}) || {}
+      @filters << Filter.new(:host, fh[:hosts]) if fh[:hosts]
+      @filters << Filter.new(:role, fh[:roles]) if fh[:roles]
       @filters << Filter.new(:host, fh[:host]) if fh[:host]
       @filters << Filter.new(:role, fh[:role]) if fh[:role]
     end

spec/integration/dsl_spec.rb

@@ -132,6 +132,38 @@ describe Capistrano::DSL do
         end
       end
 
+      describe 'setting an internal hosts filter' do
+        subject { dsl.roles(:app) }
+        it 'is ignored' do
+          dsl.set :filter, { hosts: 'example3.com' }
+          expect(subject.map(&:hostname)).to eq(['example3.com', 'example4.com'])
+        end
+      end
+
+      describe 'setting an internal roles filter' do
+        subject { dsl.roles(:app) }
+        it 'ignores it' do
+          dsl.set :filter, { roles: :web }
+          expect(subject.map(&:hostname)).to eq(['example3.com','example4.com'])
+        end
+      end
+
+      describe 'setting an internal hosts and roles filter' do
+        subject { dsl.roles(:app) }
+        it 'ignores it' do
+          dsl.set :filter, { roles: :web, hosts: 'example1.com' }
+          expect(subject.map(&:hostname)).to eq(['example3.com','example4.com'])
+        end
+      end
+
+      describe 'setting an internal regexp hosts filter' do
+        subject { dsl.roles(:all) }
+        it 'is ignored' do
+          dsl.set :filter, { hosts: /1/ }
+          expect(subject.map(&:hostname)).to eq(%w{example1.com example2.com example3.com example4.com example5.com})
+        end
+      end
+
     end
 
     describe 'when defining role with reserved name' do
@@ -496,6 +528,21 @@ describe Capistrano::DSL do
         dsl.on(all)
       end
 
+      it 'filters by roles from the :filter variable' do
+        hosts = dsl.roles(:web)
+        all = dsl.roles(:all)
+        SSHKit::Coordinator.expects(:new).with(hosts).returns(@coordinator)
+        dsl.set :filter, { roles: 'web' }
+        dsl.on(all)
+      end
+
+      it 'filters by hosts and roles from the :filter variable' do
+        all = dsl.roles(:all)
+        SSHKit::Coordinator.expects(:new).with([]).returns(@coordinator)
+        dsl.set :filter, { roles: 'db', hosts: 'example3.com' }
+        dsl.on(all)
+      end
+
       it 'filters from ENV[ROLES]' do
         hosts = dsl.roles(:db)
         all = dsl.roles(:all)
@@ -549,6 +596,24 @@ describe Capistrano::DSL do
         dsl.on('server.local')
       end
 
+      it "selects nothing when a roles filter is present" do
+        dsl.set :filter, { roles: 'web' }
+        SSHKit::Coordinator.expects(:new).with([]).returns(@coordinator)
+        dsl.on('my.server')
+      end
+
+      it "selects using the string when a hosts filter is present" do
+        dsl.set :filter, { hosts: 'server.local' }
+        SSHKit::Coordinator.expects(:new).with(['server.local']).returns(@coordinator)
+        dsl.on('server.local')
+      end
+
+      it "doesn't select when a hosts filter is present that doesn't match" do
+        dsl.set :filter, { hosts: 'ruby.local' }
+        SSHKit::Coordinator.expects(:new).with([]).returns(@coordinator)
+        dsl.on('server.local')
+      end
+
     end
 
   end