Per-session config and thread specific current_driver/session_name

README.md

@@ -67,6 +67,7 @@ You can read more about the missing features [here](https://github.com/teamcapyb
 - [Beware the XPath // trap](#beware-the-xpath--trap)
 - [Configuring and adding drivers](#configuring-and-adding-drivers)
 - [Gotchas:](#gotchas)
+- ["Threadsafe" mode](#threadsafe)
 - [Development](#development)
 
 ## <a name="key-benefits"></a>Key benefits
@@ -1048,6 +1049,31 @@ additional info about how the underlying driver can be configured.
   are testing for specific server errors and using multiple sessions make sure to test for the
   errors using the initial session (usually :default)
 
+## <a name="threadsafe"></a>"Threadsafe" mode - BETA - may change
+
+In normal mode most of Capybara's configuration options are global settings which can cause issues
+if using multiple sessions and wanting to change a setting for only one of the sessions.  To provide
+support for this type of usage Capybara now provides a "threadsafe" mode which can be enabled by setting
+
+    Capybara.threadsafe = true
+
+This setting can only be changed before any sessions have been created.  In "threadsafe" mode the following
+behaviors of Capybara change
+
+* Most options can now be set on a session.  These can either be set at session creation time or after, and
+  default to the global options at the time of session creation.  Options which are NOT session specific are
+  `app`, `reuse_server`, `default_driver`, `javascript_driver`, and (obviously) `threadsafe`.  Any drivers and servers
+  registered through `register_driver` and `register_server` are also global.
+
+      my_session = Capybara::Session.new(:driver, some_app) do |config|
+        config.automatic_label_click = true # only set for my_session
+      end
+      my_session.config.default_max_wait_time = 10 # only set for my_session
+      Capybara.default_max_wait_time = 2 # will not change the default_max_wait in my_session
+
+* `current_driver` and `session_name` are thread specific.  This means that `using_session' and
+  `using_driver` also only affect the current thread.
+
 ## <a name="development"></a>Development
 
 To set up a development environment, simply do:

lib/capybara.rb

@@ -2,6 +2,8 @@
 require 'timeout'
 require 'nokogiri'
 require 'xpath'
+require 'forwardable'
+require 'capybara/config'
 
 module Capybara
   class CapybaraError < StandardError; end
@@ -19,18 +21,41 @@ module Capybara
   class WindowError < CapybaraError; end
   class ReadOnlyElementError < CapybaraError; end
 
+
   class << self
-    attr_reader :app_host, :default_host
-    attr_accessor :asset_host, :run_server, :always_include_port
-    attr_accessor :server_port, :exact, :match, :exact_options, :visible_text_only, :enable_aria_label
-    attr_accessor :default_selector, :default_max_wait_time, :ignore_hidden_elements
-    attr_accessor :save_path, :wait_on_first_by_default, :automatic_label_click, :automatic_reload
-    attr_reader :reuse_server
-    attr_accessor :raise_server_errors, :server_errors
-    attr_writer :default_driver, :current_driver, :javascript_driver, :session_name, :server_host
-    attr_reader :save_and_open_page_path
-    attr_accessor :exact_text
-    attr_accessor :app
+    extend Forwardable
+
+    # DelegateCapybara global configurations
+    # @!method app
+    #   See {Capybara#configure}
+    # @!method reuse_server
+    #   See {Capybara#configure}
+    # @!method threadsafe
+    #   See {Capybara#configure}
+    # @!method server
+    #   See {Capybara#configure}
+    # @!method default_driver
+    #   See {Capybara#configure}
+    # @!method javascript_driver
+    #   See {Capybara#configure}
+    Config::OPTIONS.each do |method|
+      def_delegators :config, method, "#{method}="
+    end
+
+    # Delegate Capybara global configurations
+    # @!method default_selector
+    #   See {Capybara#configure}
+    # @!method default_max_wait_time
+    #   See {Capybara#configure}
+    # @!method app_host
+    #   See {Capybara#configure}
+    # @!method always_include_port
+    #   See {Capybara#configure}
+    # @!method wait_on_first_by_default
+    #   See {Capybara#configure}
+    SessionConfig::OPTIONS.each do |method|
+      def_delegators :config, method, "#{method}="
+    end
 
     ##
     #
@@ -58,6 +83,9 @@ module Capybara
     # [automatic_label_click = Boolean]   Whether Node#choose, Node#check, Node#uncheck will attempt to click the associated label element if the checkbox/radio button are non-visible (Default: false)
     # [enable_aria_label = Boolean]  Whether fields, links, and buttons will match against aria-label attribute (Default: false)
     # [reuse_server = Boolean]  Reuse the server thread between multiple sessions using the same app object (Default: true)
+    # [threadsafe = Boolean]  Whether sessions can be configured individually (Default: false)
+    # [server = Symbol]  The name of the registered server to use when running the app under test (Default: :webrick)
+    #
     # === DSL Options
     #
     # when using capybara/dsl, the following options are also available:
@@ -66,7 +94,7 @@ module Capybara
     # [javascript_driver = Symbol]        The name of a driver to use for JavaScript enabled tests. (Default: :selenium)
     #
     def configure
-      yield self
+      yield ConfigureDeprecator.new(config)
     end
 
     ##
@@ -163,45 +191,6 @@ module Capybara
       @servers ||= {}
     end
 
-    ##
-    #
-    # Register a proc that Capybara will call to run the Rack application.
-    #
-    #     Capybara.server do |app, port, host|
-    #       require 'rack/handler/mongrel'
-    #       Rack::Handler::Mongrel.run(app, :Port => port)
-    #     end
-    #
-    # By default, Capybara will try to run webrick.
-    #
-    # @yield [app, port, host]      This block receives a rack app, port, and host/ip and should run a Rack handler
-    #
-    def server(&block)
-      if block_given?
-        warn "DEPRECATED: Passing a block to Capybara::server is deprecated, please use Capybara::register_server instead"
-        @server = block
-      else
-        @server
-      end
-    end
-
-    ##
-    #
-    # Set the server to use.
-    #
-    #     Capybara.server = :webrick
-    #
-    # @param [Symbol] name     Name of the server type to use
-    # @see register_server
-    #
-    def server=(name)
-      @server = if name.respond_to? :call
-        name
-      else
-        servers[name.to_sym]
-      end
-    end
-
     ##
     #
     # Wraps the given string, which should contain an HTML document or fragment
@@ -251,29 +240,25 @@ module Capybara
       servers[:webrick].call(app, port, server_host)
     end
 
-    ##
-    #
-    # @return [Symbol]    The name of the driver to use by default
-    #
-    def default_driver
-      @default_driver || :rack_test
-    end
-
     ##
     #
     # @return [Symbol]    The name of the driver currently in use
     #
     def current_driver
-      @current_driver || default_driver
+      if threadsafe
+        Thread.current['capybara_current_driver']
+      else
+        @current_driver
+      end || default_driver
     end
     alias_method :mode, :current_driver
 
-    ##
-    #
-    # @return [Symbol]    The name of the driver used when JavaScript is needed
-    #
-    def javascript_driver
-      @javascript_driver || :selenium
+    def current_driver=(name)
+      if threadsafe
+        Thread.current['capybara_current_driver'] = name
+      else
+        @current_driver = name
+      end
     end
 
     ##
@@ -281,7 +266,7 @@ module Capybara
     # Use the default driver as the current driver
     #
     def use_default_driver
-      @current_driver = nil
+      self.current_driver = nil
     end
 
     ##
@@ -293,15 +278,7 @@ module Capybara
       Capybara.current_driver = driver
       yield
     ensure
-      @current_driver = previous_driver
-    end
-
-    ##
-    #
-    # @return [String]    The IP address bound by default server
-    #
-    def server_host
-      @server_host || '127.0.0.1'
+      self.current_driver = previous_driver
     end
 
     ##
@@ -344,7 +321,19 @@ module Capybara
     # @return [Symbol]    The name of the currently used session.
     #
     def session_name
-      @session_name ||= :default
+      if threadsafe
+        Thread.current['capybara_session_name'] ||= :default
+      else
+        @session_name ||= :default
+      end
+    end
+
+    def session_name=(name)
+      if threadsafe
+        Thread.current['capybara_session_name'] = name
+      else
+        @session_name = name
+      end
     end
 
     ##
@@ -352,11 +341,19 @@ module Capybara
     # Yield a block using a specific session name.
     #
     def using_session(name)
-      previous_session_name = self.session_name
+      previous_session_info = {
+        session_name: session_name,
+        current_driver: current_driver,
+        app: app
+      }
       self.session_name = name
       yield
     ensure
-      self.session_name = previous_session_name
+      self.session_name = previous_session_info[:session_name]
+      if threadsafe
+        self.current_driver = previous_session_info[:current_driver]
+        self.app = previous_session_info[:app]
+      end
     end
 
     ##
@@ -374,32 +371,8 @@ module Capybara
       end
     end
 
-    # @deprecated Use default_max_wait_time instead
-    def default_wait_time
-      deprecate('default_wait_time', 'default_max_wait_time', true)
-      default_max_wait_time
-    end
-
-    # @deprecated Use default_max_wait_time= instead
-    def default_wait_time=(t)
-      deprecate('default_wait_time=', 'default_max_wait_time=')
-      self.default_max_wait_time = t
-    end
-
-    def save_and_open_page_path=(path)
-      warn "DEPRECATED: #save_and_open_page_path is deprecated, please use #save_path instead. \n"\
-           "Note: Behavior is slightly different with relative paths - see documentation" unless path.nil?
-      @save_and_open_page_path = path
-    end
-
-    def app_host=(url)
-      raise ArgumentError.new("Capybara.app_host should be set to a url (http://www.example.com)") unless url.nil? || (url =~ URI::Parser.new.make_regexp)
-      @app_host = url
-    end
-
-    def default_host=(url)
-      raise ArgumentError.new("Capybara.default_host should be set to a url (http://www.example.com)") unless url.nil? || (url =~ URI::Parser.new.make_regexp)
-      @default_host = url
+    def session_options
+      config.session_options
     end
 
     def included(base)
@@ -407,18 +380,10 @@ module Capybara
       warn "`include Capybara` is deprecated. Please use `include Capybara::DSL` instead."
     end
 
-    def reuse_server=(bool)
-      warn "Capybara.reuse_server == false is a BETA feature and may change in a future version" unless bool
-      @reuse_server = bool
-    end
-
-    def deprecate(method, alternate_method, once=false)
-      @deprecation_notified ||= {}
-      warn "DEPRECATED: ##{method} is deprecated, please use ##{alternate_method} instead" unless once and @deprecation_notified[method]
-      @deprecation_notified[method]=true
-    end
-
   private
+    def config
+      @config ||= Capybara::Config.new
+    end
 
     def session_pool
       @session_pool ||= {}

lib/capybara/config.rb

@@ -0,0 +1,121 @@
+# frozen_string_literal: true
+require 'forwardable'
+require 'capybara/session/config'
+
+module Capybara
+  class Config
+    extend Forwardable
+
+    OPTIONS = [:app, :reuse_server, :threadsafe, :default_wait_time, :server, :default_driver, :javascript_driver]
+
+    attr_accessor :app
+    attr_reader :reuse_server, :threadsafe
+    attr_reader :session_options
+    attr_writer :default_driver, :javascript_driver
+
+    SessionConfig::OPTIONS.each do |method|
+      def_delegators :session_options, method, "#{method}="
+    end
+
+    def initialize
+      @session_options = Capybara::SessionConfig.new
+    end
+
+    def reuse_server=(bool)
+      @reuse_server = bool
+    end
+
+    def threadsafe=(bool)
+      warn "Capybara.threadsafe == true is a BETA feature and may change in future minor versions" if bool
+      raise "Threadsafe setting cannot be changed once a session is created" if (bool != threadsafe) && Session.instance_created?
+      @threadsafe = bool
+    end
+
+    ##
+    #
+    # Return the proc that Capybara will call to run the Rack application.
+    # The block returned receives a rack app, port, and host/ip and should run a Rack handler
+    # By default, Capybara will try to run webrick.
+    #
+    def server(&block)
+      if block_given?
+        warn "DEPRECATED: Passing a block to Capybara::server is deprecated, please use Capybara::register_server instead"
+        @server = block
+      else
+        @server
+      end
+    end
+
+    ##
+    #
+    # Set the server to use.
+    #
+    #     Capybara.server = :webrick
+    #
+    # @param [Symbol] name     Name of the server type to use
+    # @see register_server
+    #
+    def server=(name)
+      @server = if name.respond_to? :call
+        name
+      else
+        Capybara.servers[name.to_sym]
+      end
+    end
+
+    ##
+    #
+    # @return [Symbol]    The name of the driver to use by default
+    #
+    def default_driver
+      @default_driver || :rack_test
+    end
+
+    ##
+    #
+    # @return [Symbol]    The name of the driver used when JavaScript is needed
+    #
+    def javascript_driver
+      @javascript_driver || :selenium
+    end
+
+    # @deprecated Use default_max_wait_time instead
+    def default_wait_time
+      deprecate('default_wait_time', 'default_max_wait_time', true)
+      default_max_wait_time
+    end
+
+    # @deprecated Use default_max_wait_time= instead
+    def default_wait_time=(t)
+      deprecate('default_wait_time=', 'default_max_wait_time=')
+      self.default_max_wait_time = t
+    end
+
+    def deprecate(method, alternate_method, once=false)
+      @deprecation_notified ||= {}
+      warn "DEPRECATED: ##{method} is deprecated, please use ##{alternate_method} instead" unless once and @deprecation_notified[method]
+      @deprecation_notified[method]=true
+    end
+  end
+
+  class ConfigureDeprecator
+    def initialize(config)
+      @config = config
+    end
+
+    def method_missing(m, *args, &block)
+      if @config.respond_to?(m)
+        @config.public_send(m, *args, &block)
+      elsif Capybara.respond_to?(m)
+        warn "Calling #{m} from Capybara.configure is deprecated - please call it on Capybara directly ( Capybara.#{m}(...) )"
+        Capybara.public_send(m, *args, &block)
+      else
+        super
+      end
+    end
+
+    def respond_to_missing?(m, include_private = false)
+      @config.respond_to_missing?(m, include_private) || Capybara.respond_to_missing?(m, include_private)
+    end
+  end
+end

lib/capybara/driver/base.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 class Capybara::Driver::Base
+  attr_writer :session_options
+
   def current_url
     raise NotImplementedError
   end
@@ -139,6 +141,10 @@ class Capybara::Driver::Base
     false
   end
 
+  def session_options
+    @session_options || Capybara.session_options
+  end
+
   # @deprecated This method is being removed
   def browser_initialized?
     warn "DEPRECATED: #browser_initialized? is deprecated and will be removed in the next version of Capybara"

lib/capybara/dsl.rb

@@ -21,12 +21,10 @@ module Capybara
       Capybara.using_session(name, &block)
     end
 
-    ##
-    #
     # Shortcut to using a different wait time.
     #
     def using_wait_time(seconds, &block)
-      Capybara.using_wait_time(seconds, &block)
+      page.using_wait_time(seconds, &block)
     end
 
     ##

lib/capybara/helpers.rb

@@ -46,11 +46,11 @@ module Capybara
     # @param [String] html     HTML code to inject into
     # @return [String]         The modified HTML code
     #
-    def inject_asset_host(html)
-      if Capybara.asset_host && Nokogiri::HTML(html).css("base").empty?
+    def inject_asset_host(html, asset_host = Capybara.asset_host)
+      if asset_host && Nokogiri::HTML(html).css("base").empty?
         match = html.match(/<head[^<]*?>/)
         if match
-          return html.clone.insert match.end(0), "<base href='#{Capybara.asset_host}' />"
+          return html.clone.insert match.end(0), "<base href='#{asset_host}' />"
         end
       end
 

lib/capybara/node/actions.rb

@@ -293,9 +293,9 @@ module Capybara
 
       def _check_with_label(selector, checked, locator, options)
         locator, options = nil, locator if locator.is_a? Hash
-        allow_label_click = options.delete(:allow_label_click) { Capybara.automatic_label_click }
+        allow_label_click = options.delete(:allow_label_click) { session_options.automatic_label_click }
 
-        synchronize(Capybara::Queries::BaseQuery::wait(options)) do
+        synchronize(Capybara::Queries::BaseQuery.wait(options, session_options.default_max_wait_time)) do
           begin
             el = find(selector, locator, options)
             el.set(checked)

lib/capybara/node/base.rb

@@ -74,7 +74,7 @@ module Capybara
       # @return [Object]                  The result of the given block
       # @raise  [Capybara::FrozenInTime]  If the return value of `Time.now` appears stuck
       #
-      def synchronize(seconds=Capybara.default_max_wait_time, options = {})
+      def synchronize(seconds=session_options.default_max_wait_time, options = {})
         start_time = Capybara::Helpers.monotonic_time
 
         if session.synchronized
@@ -90,7 +90,7 @@ module Capybara
             raise e if (Capybara::Helpers.monotonic_time - start_time) >= seconds
             sleep(0.05)
             raise Capybara::FrozenInTime, "time appears to be frozen, Capybara does not work with libraries which freeze time, consider using time travelling instead" if Capybara::Helpers.monotonic_time == start_time
-            reload if Capybara.automatic_reload
+            reload if session_options.automatic_reload
             retry
           ensure
             session.synchronized = false
@@ -114,6 +114,11 @@ module Capybara
         query_scope
       end
 
+      # @api private
+      def session_options
+        session.config
+      end
+
     protected
 
       def catch_error?(error, errors = nil)

lib/capybara/node/element.rb

@@ -55,7 +55,7 @@ module Capybara
       # @return [String]              The text of the element
       #
       def text(type=nil)
-        type ||= :all unless Capybara.ignore_hidden_elements or Capybara.visible_text_only
+        type ||= :all unless session_options.ignore_hidden_elements or session_options.visible_text_only
         synchronize do
           if type == :all
             base.all_text

lib/capybara/node/finders.rb

@@ -29,11 +29,16 @@ module Capybara
       # @raise  [Capybara::ElementNotFound]    If the element can't be found before time expires
       #
       def find(*args, &optional_filter_block)
+        if args.last.is_a? Hash
+          args.last[:session_options] = session_options
+        else
+          args.push(session_options: session_options)
+        end
         query = Capybara::Queries::SelectorQuery.new(*args, &optional_filter_block)
         synchronize(query.wait) do
-          if (query.match == :smart or query.match == :prefer_exact) and query.supports_exact?
+          if (query.match == :smart or query.match == :prefer_exact)
             result = query.resolve_for(self, true)
-            result = query.resolve_for(self, false) if result.empty? && !query.exact?
+            result = query.resolve_for(self, false) if result.empty? && query.supports_exact? && !query.exact?
           else
             result = query.resolve_for(self)
           end
@@ -208,6 +213,11 @@ module Capybara
       # @return [Capybara::Result]                   A collection of found elements
       #
       def all(*args, &optional_filter_block)
+        if args.last.is_a? Hash
+          args.last[:session_options] = session_options
+        else
+          args.push(session_options: session_options)
+        end
         query = Capybara::Queries::SelectorQuery.new(*args, &optional_filter_block)
         synchronize(query.wait) do
           result = query.resolve_for(self)
@@ -233,7 +243,7 @@ module Capybara
       # @return [Capybara::Node::Element]            The found element or nil
       #
       def first(*args, &optional_filter_block)
-        if Capybara.wait_on_first_by_default
+        if session_options.wait_on_first_by_default
           options = if args.last.is_a?(Hash) then args.pop.dup else {} end
           args.push({minimum: 1}.merge(options))
         end

lib/capybara/node/matchers.rb

@@ -114,8 +114,8 @@ module Capybara
       #
       def assert_all_of_selectors(*args, &optional_filter_block)
         options = if args.last.is_a?(Hash) then args.pop.dup else {} end
-        selector = if args.first.is_a?(Symbol) then args.shift else Capybara.default_selector end
-        wait = options.fetch(:wait, Capybara.default_max_wait_time)
+        selector = if args.first.is_a?(Symbol) then args.shift else session_options.default_selector end
+        wait = options.fetch(:wait, session_options.default_max_wait_time)
         synchronize(wait) do
           args.each do |locator|
             assert_selector(selector, locator, options, &optional_filter_block)
@@ -140,8 +140,8 @@ module Capybara
       #
       def assert_none_of_selectors(*args, &optional_filter_block)
         options = if args.last.is_a?(Hash) then args.pop.dup else {} end
-        selector = if args.first.is_a?(Symbol) then args.shift else Capybara.default_selector end
-        wait = options.fetch(:wait, Capybara.default_max_wait_time)
+        selector = if args.first.is_a?(Symbol) then args.shift else session_options.default_selector end
+        wait = options.fetch(:wait, session_options.default_max_wait_time)
         synchronize(wait) do
           args.each do |locator|
             assert_no_selector(selector, locator, options, &optional_filter_block)
@@ -680,6 +680,7 @@ module Capybara
     private
 
       def _verify_selector_result(query_args, optional_filter_block, &result_block)
+        _set_query_session_options(query_args)
         query = Capybara::Queries::SelectorQuery.new(*query_args, &optional_filter_block)
         synchronize(query.wait) do
           result = query.resolve_for(self)
@@ -689,6 +690,7 @@ module Capybara
       end
 
       def _verify_match_result(query_args, optional_filter_block, &result_block)
+        _set_query_session_options(query_args)
         query = Capybara::Queries::MatchQuery.new(*query_args, &optional_filter_block)
         synchronize(query.wait) do
           result = query.resolve_for(self.query_scope)
@@ -698,6 +700,7 @@ module Capybara
       end
 
       def _verify_text(query_args)
+        _set_query_session_options(query_args)
         query = Capybara::Queries::TextQuery.new(*query_args)
         synchronize(query.wait) do
           count = query.resolve_for(self)
@@ -706,6 +709,14 @@ module Capybara
         return true
       end
 
+      def _set_query_session_options(query_args)
+        if query_args.last.is_a? Hash
+          query_args.last[:session_options] = session_options
+        else
+          query_args.push(session_options: session_options)
+        end
+        query_args
+      end
     end
   end
 end

lib/capybara/node/simple.rb

@@ -173,6 +173,11 @@ module Capybara
       def find_xpath(xpath)
         native.xpath(xpath)
       end
+
+      # @api private
+      def session_options
+        Capybara.session_options
+      end
     end
   end
 end

lib/capybara/queries/base_query.rb

@@ -6,13 +6,18 @@ module Capybara
       COUNT_KEYS = [:count, :minimum, :maximum, :between]
 
       attr_reader :options
+      attr_writer :session_options
 
-      def wait
-        self.class.wait(options)
+      def session_options
+        @session_options || Capybara.session_options
       end
 
-      def self.wait(options)
-        options.fetch(:wait, Capybara.default_max_wait_time) || 0
+      def wait
+        self.class.wait(options, session_options.default_max_wait_time)
+      end
+
+      def self.wait(options, default=Capybara.default_max_wait_time)
+        options.fetch(:wait, default) || 0
       end
 
       ##

lib/capybara/queries/selector_query.rb

@@ -9,11 +9,13 @@ module Capybara
 
       def initialize(*args, &filter_block)
         @options = if args.last.is_a?(Hash) then args.pop.dup else {} end
+        self.session_options = @options.delete(:session_options)
+
         @filter_block = filter_block
 
         if args[0].is_a?(Symbol)
           @selector = Selector.all.fetch(args.shift) do |selector_type|
-            warn "Unknown selector type (:#{selector_type}), defaulting to :#{Capybara.default_selector} - This will raise an exception in a future version of Capybara"
+            raise ArgumentError, "Unknown selector type (:#{selector_type})"
             nil
           end
           @locator = args.shift
@@ -21,16 +23,16 @@ module Capybara
           @selector = Selector.all.values.find { |s| s.match?(args[0]) }
           @locator = args.shift
         end
-        @selector ||= Selector.all[Capybara.default_selector]
+        @selector ||= Selector.all[session_options.default_selector]
 
         warn "Unused parameters passed to #{self.class.name} : #{args.to_s}" unless args.empty?
 
         # for compatibility with Capybara 2.0
-        if Capybara.exact_options and @selector == Selector.all[:option]
+        if session_options.exact_options and @selector == Selector.all[:option]
           @options[:exact] = true
         end
 
-        @expression = @selector.call(@locator, @options)
+        @expression = @selector.call(@locator, @options.merge(enable_aria_label: session_options.enable_aria_label))
 
         warn_exact_usage
 
@@ -89,12 +91,12 @@ module Capybara
           end
         end
 
-        res &&= Capybara.using_wait_time(0){ @filter_block.call(node)} unless @filter_block.nil?
+        res &&= node.session.using_wait_time(0){ @filter_block.call(node)} unless @filter_block.nil?
         res
       end
 
       def visible
-        case (vis = options.fetch(:visible){ @selector.default_visibility })
+        case (vis = options.fetch(:visible){ @selector.default_visibility(session_options.ignore_hidden_elements) })
           when true then :visible
           when false then :all
           else vis
@@ -103,11 +105,11 @@ module Capybara
 
       def exact?
         return false if !supports_exact?
-        options.fetch(:exact, Capybara.exact)
+        options.fetch(:exact, session_options.exact)
       end
 
       def match
-        options.fetch(:match, Capybara.match)
+        options.fetch(:match, session_options.match)
       end
 
       def xpath(exact=nil)
@@ -205,7 +207,7 @@ module Capybara
       end
 
       def exact_text
-        options.fetch(:exact_text, Capybara.exact_text)
+        options.fetch(:exact_text, session_options.exact_text)
       end
     end
   end

lib/capybara/queries/text_query.rb

@@ -5,13 +5,18 @@ module Capybara
     class TextQuery < BaseQuery
       def initialize(*args)
         @type = (args.first.is_a?(Symbol) || args.first.nil?) ? args.shift : nil
-        @type = (Capybara.ignore_hidden_elements or Capybara.visible_text_only) ? :visible : :all if @type.nil?
-        @expected_text, @options = args
+        # @type = (Capybara.ignore_hidden_elements or Capybara.visible_text_only) ? :visible : :all if @type.nil?
+        @options = if args.last.is_a?(Hash) then args.pop.dup else {} end
+        self.session_options = @options.delete(:session_options)
+
+        @type = (session_options.ignore_hidden_elements or session_options.visible_text_only) ? :visible : :all if @type.nil?
+
+        @expected_text = args.shift
         unless @expected_text.is_a?(Regexp)
           @expected_text = Capybara::Helpers.normalize_whitespace(@expected_text)
         end
-        @options ||= {}
         @search_regexp = Capybara::Helpers.to_regexp(@expected_text, nil, exact?)
+        warn "Unused parameters passed to #{self.class.name} : #{args.to_s}" unless args.empty?
         assert_valid_keys
       end
 
@@ -40,7 +45,7 @@ module Capybara
       private
 
       def exact?
-        options.fetch(:exact, Capybara.exact_text)
+        options.fetch(:exact, session_options.exact_text)
       end
 
       def build_message(report_on_invisible)

lib/capybara/rack_test/browser.rb

@@ -71,7 +71,7 @@ class Capybara::RackTest::Browser
   end
 
   def reset_host!
-    uri = URI.parse(Capybara.app_host || Capybara.default_host)
+    uri = URI.parse(driver.session_options.app_host || driver.session_options.default_host)
     @current_scheme = uri.scheme
     @current_host = uri.host
     @current_port = uri.port

lib/capybara/rspec/matchers.rb

@@ -7,7 +7,7 @@ module Capybara
       attr_reader :failure_message, :failure_message_when_negated
 
       def wrap(actual)
-        if actual.respond_to?("has_selector?")
+        @context_el = if actual.respond_to?("has_selector?")
           actual
         else
           Capybara.string(actual.to_s)
@@ -33,6 +33,19 @@ module Capybara
         @failure_message_when_negated = e.message
         return false
       end
+
+      def session_query_args
+        if @args.last.is_a? Hash
+          @args.last[:session_options] = session_options
+        else
+          @args.push(session_options: session_options)
+        end
+        @args
+      end
+
+      def session_options
+        @context_el ? @context_el.session_options : Capybara.session_options
+      end
     end
 
     class HaveSelector < Matcher
@@ -55,7 +68,7 @@ module Capybara
       end
 
       def query
-        @query ||= Capybara::Queries::SelectorQuery.new(*@args, &@filter_block)
+        @query ||= Capybara::Queries::SelectorQuery.new(*session_query_args, &@filter_block)
       end
     end
 
@@ -73,7 +86,7 @@ module Capybara
       end
 
       def query
-        @query ||= Capybara::Queries::MatchQuery.new(*@args)
+        @query ||= Capybara::Queries::MatchQuery.new(*session_query_args, &@filter_block)
       end
     end
 
@@ -155,11 +168,12 @@ module Capybara
 
     class BecomeClosed
       def initialize(options)
-        @wait_time = Capybara::Queries::BaseQuery.wait(options)
+        @options = options
       end
 
       def matches?(window)
         @window = window
+        @wait_time = Capybara::Queries::BaseQuery.wait(@options, window.session.config.default_max_wait_time)
         start_time = Capybara::Helpers.monotonic_time
         while window.exists?
           return false if (Capybara::Helpers.monotonic_time - start_time) > @wait_time

lib/capybara/selector.rb

@@ -139,7 +139,7 @@ Capybara.add_selector(:link) do
                  XPath.string.n.is(locator) |
                  XPath.attr(:title).is(locator) |
                  XPath.descendant(:img)[XPath.attr(:alt).is(locator)]
-      matchers |= XPath.attr(:'aria-label').is(locator) if Capybara.enable_aria_label
+      matchers |= XPath.attr(:'aria-label').is(locator) if options[:enable_aria_label]
       xpath = xpath[matchers]
     end
     xpath = [:title].inject(xpath) { |memo, ef| memo[find_by_attr(ef, options[ef])] }
@@ -185,14 +185,14 @@ Capybara.add_selector(:button) do
     unless locator.nil?
       locator = locator.to_s
       locator_matches = XPath.attr(:id).equals(locator) | XPath.attr(:value).is(locator) | XPath.attr(:title).is(locator)
-      locator_matches |= XPath.attr(:'aria-label').is(locator) if Capybara.enable_aria_label
+      locator_matches |= XPath.attr(:'aria-label').is(locator) if options[:enable_aria_label]
 
       input_btn_xpath = input_btn_xpath[locator_matches]
 
       btn_xpath = btn_xpath[locator_matches | XPath.string.n.is(locator) | XPath.descendant(:img)[XPath.attr(:alt).is(locator)]]
 
       alt_matches = XPath.attr(:alt).is(locator)
-      alt_matches |= XPath.attr(:'aria-label').is(locator) if Capybara.enable_aria_label
+      alt_matches |= XPath.attr(:'aria-label').is(locator) if options[:enable_aria_label]
       image_btn_xpath = image_btn_xpath[alt_matches]
     end
 

lib/capybara/selector/selector.rb

@@ -201,9 +201,9 @@ module Capybara
       @default_visibility = default_visibility
     end
 
-    def default_visibility
+    def default_visibility(fallback = Capybara.ignore_hidden_elements)
       if @default_visibility.nil?
-        Capybara.ignore_hidden_elements
+        fallback
       else
         @default_visibility
       end
@@ -219,7 +219,7 @@ module Capybara
                          XPath.attr(:name).equals(locator) |
                          XPath.attr(:placeholder).equals(locator) |
                          XPath.attr(:id).equals(XPath.anywhere(:label)[XPath.string.n.is(locator)].attr(:for))
-        attr_matchers |= XPath.attr(:'aria-label').is(locator) if Capybara.enable_aria_label
+        attr_matchers |= XPath.attr(:'aria-label').is(locator) if options[:enable_aria_label]
 
         locate_xpath = locate_xpath[attr_matchers]
         locate_xpath += XPath.descendant(:label)[XPath.string.n.is(locator)].descendant(xpath)

lib/capybara/selenium/driver.rb

@@ -320,7 +320,7 @@ class Capybara::Selenium::Driver < Capybara::Driver::Base
     # Selenium has its own built in wait (2 seconds)for a modal to show up, so this wait is really the minimum time
     # Actual wait time may be longer than specified
     wait = Selenium::WebDriver::Wait.new(
-      timeout: (options[:wait] || Capybara.default_max_wait_time),
+      timeout: options.fetch(:wait, session_options.default_max_wait_time) || 0 ,
       ignore: Selenium::WebDriver::Error::NoAlertPresentError)
     begin
       wait.until do

lib/capybara/server.rb

@@ -25,9 +25,10 @@ module Capybara
 
       attr_accessor :error
 
-      def initialize(app)
+      def initialize(app, server_errors)
         @app = app
         @counter = Counter.new
+        @server_errors = server_errors
       end
 
       def pending_requests?
@@ -41,7 +42,7 @@ module Capybara
           @counter.increment
           begin
             @app.call(env)
-          rescue *Capybara.server_errors => e
+          rescue *@server_errors => e
             @error = e unless @error
             raise e
           ensure
@@ -59,10 +60,10 @@ module Capybara
 
     attr_reader :app, :port, :host
 
-    def initialize(app, port=Capybara.server_port, host=Capybara.server_host)
+    def initialize(app, port=Capybara.server_port, host=Capybara.server_host, server_errors=Capybara.server_errors)
       @app = app
       @server_thread = nil # suppress warnings
-      @host, @port = host, port
+      @host, @port, @server_errors = host, port, server_errors
       @port ||= Capybara::Server.ports[port_key]
       @port ||= find_available_port(host)
     end
@@ -112,7 +113,7 @@ module Capybara
   private
 
     def middleware
-      @middleware ||= Middleware.new(app)
+      @middleware ||= Middleware.new(app, @server_errors)
     end
 
     def port_key

lib/capybara/session.rb

@@ -17,6 +17,14 @@ module Capybara
   #     session = Capybara::Session.new(:culerity)
   #     session.visit('http://www.google.com')
   #
+  # When Capybara.threadsafe == true the sessions options will be initially set to the
+  # current values of the global options and a configuration block can be passed to the session initializer.
+  # For available options see {Capybara::SessionConfig::OPTIONS}
+  #
+  #     session = Capybara::Session.new(:driver, MyRackApp) do |config|
+  #       config.app_host = "http://my_host.dev"
+  #     end
+  #
   # Session provides a number of methods for controlling the navigation of the page, such as +visit+,
   # +current_path, and so on. It also delegate a number of methods to a Capybara::Document, representing
   # the current HTML document. This allows interaction:
@@ -69,10 +77,15 @@ module Capybara
 
     def initialize(mode, app=nil)
       raise TypeError, "The second parameter to Session::new should be a rack app if passed." if app && !app.respond_to?(:call)
+      @@instance_created = true
       @mode = mode
       @app = app
-      if Capybara.run_server and @app and driver.needs_server?
-        @server = Capybara::Server.new(@app).boot
+      if block_given?
+        raise "A configuration block is only accepted when Capybara.threadsafe == true" unless Capybara.threadsafe
+        yield config if block_given?
+      end
+      if config.run_server and @app and driver.needs_server?
+        @server = Capybara::Server.new(@app, config.server_port, config.server_host, config.server_errors).boot
       else
         @server = nil
       end
@@ -85,7 +98,9 @@ module Capybara
           other_drivers = Capybara.drivers.keys.map { |key| key.inspect }
           raise Capybara::DriverNotFoundError, "no driver called #{mode.inspect} was found, available drivers: #{other_drivers.join(', ')}"
         end
-        Capybara.drivers[mode].call(app)
+        driver = Capybara.drivers[mode].call(app)
+        driver.session_options = config
+        driver
       end
     end
 
@@ -126,7 +141,7 @@ module Capybara
       if @server and @server.error
         # Force an explanation for the error being raised as the exception cause
         begin
-          if Capybara.raise_server_errors
+          if config.raise_server_errors
             raise CapybaraError, "Your application server raised an error - It has been raised in your test code because Capybara.raise_server_errors == true"
           end
         rescue CapybaraError
@@ -235,10 +250,10 @@ module Capybara
       visit_uri = URI.parse(visit_uri.to_s)
 
       uri_base = if @server
-        visit_uri.port = @server.port if Capybara.always_include_port && (visit_uri.port == visit_uri.default_port)
-        URI.parse(Capybara.app_host || "http://#{@server.host}:#{@server.port}")
+        visit_uri.port = @server.port if config.always_include_port && (visit_uri.port == visit_uri.default_port)
+        URI.parse(config.app_host || "http://#{@server.host}:#{@server.port}")
       else
-        Capybara.app_host && URI.parse(Capybara.app_host)
+        config.app_host && URI.parse(config.app_host)
       end
 
       # TODO - this is only for compatability with previous 2.x behavior that concatenated
@@ -481,7 +496,7 @@ module Capybara
         driver.switch_to_window(window.handle)
         window
       else
-        wait_time = Capybara::Queries::BaseQuery.wait(options)
+        wait_time = Capybara::Queries::BaseQuery.wait(options, config.default_max_wait_time)
         document.synchronize(wait_time, errors: [Capybara::WindowError]) do
           original_window_handle = driver.current_window_handle
           begin
@@ -578,7 +593,7 @@ module Capybara
       old_handles = driver.window_handles
       block.call
 
-      wait_time = Capybara::Queries::BaseQuery.wait(options)
+      wait_time = Capybara::Queries::BaseQuery.wait(options, config.default_max_wait_time)
       document.synchronize(wait_time, errors: [Capybara::WindowError]) do
         opened_handles = (driver.window_handles - old_handles)
         if opened_handles.size != 1
@@ -701,7 +716,7 @@ module Capybara
     #
     def save_page(path = nil)
       path = prepare_path(path, 'html')
-      File.write(path, Capybara::Helpers.inject_asset_host(body), mode: 'wb')
+      File.write(path, Capybara::Helpers.inject_asset_host(body, config.asset_host), mode: 'wb')
       path
     end
 
@@ -786,7 +801,49 @@ module Capybara
       scope
     end
 
+    ##
+    #
+    # Yield a block using a specific wait time
+    #
+    def using_wait_time(seconds)
+      if Capybara.threadsafe
+        begin
+          previous_wait_time = config.default_max_wait_time
+          config.default_max_wait_time = seconds
+          yield
+        ensure
+          config.default_max_wait_time = previous_wait_time
+        end
+      else
+        Capybara.using_wait_time(seconds) { yield }
+      end
+    end
+
+    ##
+    #
+    #  Accepts a block to set the configuration options if Capybara.threadsafe == true. Note that some options only have an effect
+    #  if set at initialization time, so look at the configuration block that can be passed to the initializer too
+    #
+    def configure
+      raise "Session configuration is only supported when Capybara.threadsafe == true" unless Capybara.threadsafe
+      yield config
+    end
+
+    def self.instance_created?
+      @@instance_created
+    end
+
+    def config
+      @config ||= if Capybara.threadsafe
+        Capybara.session_options.dup
+      else
+        Capybara::ReadOnlySessionConfig.new(Capybara.session_options)
+      end
+    end
   private
+
+    @@instance_created = false
+
     def accept_modal(type, text_or_options, options, &blk)
       driver.accept_modal(type, modal_options(text_or_options, options), &blk)
     end
@@ -798,7 +855,7 @@ module Capybara
     def modal_options(text_or_options, options)
       text_or_options, options = nil, text_or_options if text_or_options.is_a?(Hash)
       options[:text] ||= text_or_options unless text_or_options.nil?
-      options[:wait] ||= Capybara.default_max_wait_time
+      options[:wait] ||= config.default_max_wait_time
       options
     end
 
@@ -814,10 +871,10 @@ module Capybara
     end
 
     def prepare_path(path, extension)
-      if Capybara.save_path || Capybara.save_and_open_page_path.nil?
-        path = File.expand_path(path || default_fn(extension), Capybara.save_path)
+      if config.save_path || config.save_and_open_page_path.nil?
+        path = File.expand_path(path || default_fn(extension), config.save_path)
       else
-        path = File.expand_path(default_fn(extension), Capybara.save_and_open_page_path) if path.nil?
+        path = File.expand_path(default_fn(extension), config.save_and_open_page_path) if path.nil?
       end
       FileUtils.mkdir_p(File.dirname(path))
       path

lib/capybara/session/config.rb

@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+require 'delegate'
+
+module Capybara
+  class SessionConfig
+    OPTIONS = [:always_include_port, :run_server, :default_selector, :default_max_wait_time, :ignore_hidden_elements,
+               :automatic_reload, :match, :exact, :exact_text, :raise_server_errors, :visible_text_only, :wait_on_first_by_default,
+               :automatic_label_click, :enable_aria_label, :save_path, :exact_options, :asset_host, :default_host, :app_host,
+               :save_and_open_page_path, :server_host, :server_port, :server_errors]
+
+    attr_accessor *OPTIONS
+
+    ##
+    #@!method always_include_port
+    #  See {Capybara#configure}
+    #@!method run_server
+    #  See {Capybara#configure}
+    #@!method default_selector
+    #  See {Capybara#configure}
+    #@!method default_max_wait_time
+    #  See {Capybara#configure}
+    #@!method ignore_hidden_elements
+    #  See {Capybara#configure}
+    #@!method automatic_reload
+    #  See {Capybara#configure}
+    #@!method match
+    #  See {Capybara#configure}
+    #@!method exact
+    #  See {Capybara#configure}
+    #@!method raise_server_errors
+    #  See {Capybara#configure}
+    #@!method visible_text_only
+    #  See {Capybara#configure}
+    #@!method wait_on_first_by_default
+    #  See {Capybara#configure}
+    #@!method automatic_label_click
+    #  See {Capybara#configure}
+    #@!method enable_aria_label
+    #  See {Capybara#configure}
+    #@!method save_path
+    #  See {Capybara#configure}
+    #@!method exact_options
+    #  See {Capybara#configure}
+    #@!method asset_host
+    #  See {Capybara#configure}
+    #@!method default_host
+    #  See {Capybara#configure}
+    #@!method app_host
+    #  See {Capybara#configure}
+    #@!method save_and_open_page_path
+    #  See {Capybara#configure}
+    #@!method server_host
+    #  See {Capybara#configure}
+    #@!method server_port
+    #  See {Capybara#configure}
+    #@!method server_errors
+    #  See {Capybara#configure}
+
+    ##
+    #
+    # @return [String]    The IP address bound by default server
+    #
+    def server_host
+      @server_host || '127.0.0.1'
+    end
+
+    def server_errors=(errors)
+      (@server_errors ||= []).replace(errors.dup)
+    end
+
+    def app_host=(url)
+      raise ArgumentError.new("Capybara.app_host should be set to a url (http://www.example.com)") unless url.nil? || (url =~ URI::Parser.new.make_regexp)
+      @app_host = url
+    end
+
+    def default_host=(url)
+      raise ArgumentError.new("Capybara.default_host should be set to a url (http://www.example.com)") unless url.nil? || (url =~ URI::Parser.new.make_regexp)
+      @default_host = url
+    end
+
+    def save_and_open_page_path=(path)
+      warn "DEPRECATED: #save_and_open_page_path is deprecated, please use #save_path instead. \n"\
+           "Note: Behavior is slightly different with relative paths - see documentation" unless path.nil?
+      @save_and_open_page_path = path
+    end
+
+    def initialize_copy(other)
+      super
+      @server_errors = @server_errors.dup
+    end
+  end
+
+  class ReadOnlySessionConfig < SimpleDelegator
+    SessionConfig::OPTIONS.each do |m|
+      define_method "#{m}=" do |val|
+        raise "Per session settings are only supported when Capybara.threadsafe == true"
+      end
+    end
+  end
+end

lib/capybara/spec/public/test.js

@@ -58,7 +58,7 @@ $(function() {
   $('#change-title').click(function() {
     setTimeout(function() {
       $('title').text('changed title')
-    }, 250)
+    }, 400)
   });
   $('#click-test').on({
     dblclick: function() {

lib/capybara/spec/session/all_spec.rb

@@ -66,6 +66,17 @@ Capybara::SpecHelper.spec "#all" do
       Capybara.ignore_hidden_elements = false
       expect(@session.all(:css, "a.simple").size).to eq(2)
     end
+
+    context "with per session config", requires: [:psc] do
+      it "should use the sessions ignore_hidden_elements", psc: true do
+        Capybara.ignore_hidden_elements = true
+        @session.config.ignore_hidden_elements = false
+        expect(Capybara.ignore_hidden_elements).to eq(true)
+        expect(@session.all(:css, "a.simple").size).to eq(2)
+        @session.config.ignore_hidden_elements = true
+        expect(@session.all(:css, "a.simple").size).to eq(1)
+      end
+    end
   end
 
   context 'with element count filters' do

lib/capybara/spec/session/assert_all_of_selectors_spec.rb

@@ -18,10 +18,18 @@ Capybara::SpecHelper.spec '#assert_all_of_selectors' do
     @session.assert_all_of_selectors("p a#foo", "h2#h2two", "h2#h2one" )
   end
 
-  it "should respect scopes" do
-    @session.within "//p[@id='first']" do
-      @session.assert_all_of_selectors(".//a[@id='foo']")
-      expect { @session.assert_all_of_selectors(".//a[@id='red']") }.to raise_error(Capybara::ElementNotFound)
+  context "should respect scopes" do
+    it "when used with `within`" do
+      @session.within "//p[@id='first']" do
+        @session.assert_all_of_selectors(".//a[@id='foo']")
+        expect { @session.assert_all_of_selectors(".//a[@id='red']") }.to raise_error(Capybara::ElementNotFound)
+      end
+    end
+
+    it "when called on elements" do
+      el = @session.find "//p[@id='first']"
+      el.assert_all_of_selectors(".//a[@id='foo']")
+      expect { el.assert_all_of_selectors(".//a[@id='red']") }.to raise_error(Capybara::ElementNotFound)
     end
   end
 
@@ -65,10 +73,18 @@ Capybara::SpecHelper.spec '#assert_none_of_selectors' do
     expect { @session.assert_none_of_selectors("abbr", "p a#foo") }.to raise_error(Capybara::ElementNotFound)
   end
 
-  it "should respect scopes" do
-    @session.within "//p[@id='first']" do
-      expect { @session.assert_none_of_selectors(".//a[@id='foo']") }.to raise_error(Capybara::ElementNotFound)
-      @session.assert_none_of_selectors(".//a[@id='red']")
+  context "should respect scopes" do
+    it "when used with `within`" do
+      @session.within "//p[@id='first']" do
+        expect { @session.assert_none_of_selectors(".//a[@id='foo']") }.to raise_error(Capybara::ElementNotFound)
+        @session.assert_none_of_selectors(".//a[@id='red']")
+      end
+    end
+
+    it "when called on an element" do
+      el = @session.find "//p[@id='first']"
+      expect { el.assert_none_of_selectors(".//a[@id='foo']") }.to raise_error(Capybara::ElementNotFound)
+      el.assert_none_of_selectors(".//a[@id='red']")
     end
   end
 

lib/capybara/spec/session/find_spec.rb

@@ -421,8 +421,9 @@ Capybara::SpecHelper.spec '#find' do
     end
   end
 
-  it "should warn if selector type is unknown" do
-    expect_any_instance_of(Kernel).to receive(:warn).with(/^Unknown selector type/)
-    @session.find(:unknown, '//h1')
+  it "should raise if selector type is unknown" do
+    expect do
+      @session.find(:unknown, '//h1')
+    end.to raise_error(ArgumentError)
   end
 end

lib/capybara/spec/session/reset_session_spec.rb

@@ -88,7 +88,7 @@ Capybara::SpecHelper.spec '#reset_session!' do
   end
 
   it "raises configured errors caught inside the server", requires: [:server] do
-    prev_errors = Capybara.server_errors
+    prev_errors = Capybara.server_errors.dup
 
     Capybara.server_errors = [LoadError]
     quietly { @session.visit("/error") }

lib/capybara/spec/session/window/become_closed_spec.rb

@@ -60,18 +60,18 @@ Capybara::SpecHelper.spec '#become_closed', requires: [:windows, :js] do
   end
 
   context 'with not_to' do
-    it 'should raise error if default_max_wait_time is more than timeout' do
+    it "should not raise error if window doesn't close before default_max_wait_time" do
       @session.within_window @other_window do
-        @session.execute_script('setTimeout(function(){ window.close(); }, 700);')
+        @session.execute_script('setTimeout(function(){ window.close(); }, 1000);')
       end
-      Capybara.using_wait_time 0.4 do
+      Capybara.using_wait_time 0.3 do
         expect do
           expect(@other_window).not_to become_closed
         end
       end
     end
 
-    it 'should raise error if default_max_wait_time is more than timeout' do
+    it 'should raise error if window closes before default_max_wait_time' do
       @session.within_window @other_window do
         @session.execute_script('setTimeout(function(){ window.close(); }, 700);')
       end

lib/capybara/spec/spec_helper.rb

@@ -39,6 +39,7 @@ module Capybara
         Capybara.match = :smart
         Capybara.wait_on_first_by_default = false
         Capybara.enable_aria_label = false
+        reset_threadsafe
       end
 
       def filter(requires, metadata)
@@ -64,9 +65,19 @@ module Capybara
           before do
             @session = session
           end
+
           after do
             @session.reset_session!
           end
+
+          before :each, psc: true do
+            SpecHelper.reset_threadsafe(true, @session)
+          end
+
+          after psc: true do
+            SpecHelper.reset_threadsafe(false, @session)
+          end
+
           specs.each do |spec_name, spec_options, block|
             describe spec_name, spec_options do
               class_eval(&block)
@@ -74,6 +85,13 @@ module Capybara
           end
         end
       end
+
+      def reset_threadsafe(bool = false, session = nil)
+        Capybara::Session.class_variable_set(:@@instance_created, false) # Work around limit on when threadsafe can be changed
+        Capybara.threadsafe = bool
+        session = session.current_session if session.respond_to?(:current_session)
+        session.instance_variable_set(:@config, nil) if session
+      end
     end # class << self
 
     def silence_stream(stream)

lib/capybara/window.rb

@@ -115,7 +115,7 @@ module Capybara
 
     private
 
-    def wait_for_stable_size(seconds=Capybara.default_max_wait_time)
+    def wait_for_stable_size(seconds=session.config.default_max_wait_time)
       res = yield if block_given?
       prev_size = size
       start_time = Capybara::Helpers.monotonic_time

spec/capybara_spec.rb

@@ -14,8 +14,8 @@ RSpec.describe Capybara do
     end
 
     it "should be accesible as the deprecated default_wait_time" do
-      expect(Capybara).to receive(:warn).ordered.with('DEPRECATED: #default_wait_time= is deprecated, please use #default_max_wait_time= instead')
-      expect(Capybara).to receive(:warn).ordered.with('DEPRECATED: #default_wait_time is deprecated, please use #default_max_wait_time instead')
+      expect(Capybara.send(:config)).to receive(:warn).ordered.with('DEPRECATED: #default_wait_time= is deprecated, please use #default_max_wait_time= instead')
+      expect(Capybara.send(:config)).to receive(:warn).ordered.with('DEPRECATED: #default_wait_time is deprecated, please use #default_max_wait_time instead')
       @previous_default_time = Capybara.default_max_wait_time
       Capybara.default_wait_time = 5
       expect(Capybara.default_wait_time).to eq(5)
@@ -114,6 +114,18 @@ RSpec.describe Capybara do
       expect { Capybara.default_host = "http://www.example.com" }.not_to raise_error
     end
   end
+
+  describe "configure" do
+    it 'deprecates calling non configuration option methods in configure' do
+      expect_any_instance_of(Kernel).to receive(:warn).
+        with('Calling register_driver from Capybara.configure is deprecated - please call it on Capybara directly ( Capybara.register_driver(...) )')
+      Capybara.configure do |config|
+        config.register_driver(:random_name) do
+          #just a random block
+        end
+      end
+    end
+  end
 end
 
 RSpec.describe Capybara::Session do

spec/dsl_spec.rb

@@ -16,6 +16,7 @@ Capybara::SpecHelper.run_specs TestClass.new, "DSL", capybara_skip: [
   :server,
   :hover,
   :about_scheme,
+  :psc
 ]
 
 RSpec.describe Capybara::DSL do

spec/per_session_config_spec.rb

@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+require 'spec_helper'
+require 'capybara/dsl'
+
+RSpec.describe Capybara::SessionConfig do
+  describe "threadsafe" do
+    it "defaults to global session options" do
+      Capybara.threadsafe = true
+      session = Capybara::Session.new(:rack_test, TestApp)
+      [:default_host, :app_host, :save_and_open_page_path,
+       :always_include_port, :run_server, :default_selector, :default_max_wait_time, :ignore_hidden_elements,
+       :automatic_reload, :match, :exact, :raise_server_errors, :visible_text_only, :wait_on_first_by_default,
+       :automatic_label_click, :enable_aria_label,
+       :save_path, :exact_options, :asset_host].each do |m|
+         expect(session.config.public_send(m)).to eq Capybara.public_send(m)
+       end
+    end
+
+    it "doesn't change global session when changed" do
+      Capybara.threadsafe = true
+      host = "http://my.example.com"
+      session = Capybara::Session.new(:rack_test, TestApp) do |config|
+        config.default_host = host
+        config.automatic_label_click = !config.automatic_label_click
+        config.server_errors << ArgumentError
+      end
+      expect(Capybara.default_host).not_to eq host
+      expect(session.config.default_host).to eq host
+      expect(Capybara.automatic_label_click).not_to eq session.config.automatic_label_click
+      expect(Capybara.server_errors).not_to eq session.config.server_errors
+    end
+
+    it "doesn't allow session configuration block when false" do
+      Capybara.threadsafe = false
+      expect do
+        Capybara::Session.new(:rack_test, TestApp) { |config| }
+      end.to raise_error "A configuration block is only accepted when Capybara.threadsafe == true"
+    end
+
+    it "doesn't allow session config when false" do
+      Capybara.threadsafe = false
+      session = Capybara::Session.new(:rack_test, TestApp)
+      expect { session.config.default_selector = :title }.to raise_error /Per session settings are only supported when Capybara.threadsafe == true/
+      expect do
+        session.configure do |config|
+          config.exact = true
+        end
+      end.to raise_error /Session configuration is only supported when Capybara.threadsafe == true/
+    end
+
+    it "uses the config from the session" do
+      Capybara.threadsafe = true
+      session = Capybara::Session.new(:rack_test, TestApp) do |config|
+        config.default_selector = :link
+      end
+      session.visit('/with_html')
+      expect(session.find('foo').tag_name).to eq 'a'
+    end
+
+    it "won't change threadsafe once a session is created" do
+      Capybara.threadsafe = true
+      Capybara.threadsafe = false
+      session = Capybara::Session.new(:rack_test, TestApp)
+      expect { Capybara.threadsafe = true }.to raise_error /Threadsafe setting cannot be changed once a session is created/
+    end
+  end
+end

spec/rspec/shared_spec_matchers.rb

@@ -555,8 +555,8 @@ RSpec.shared_examples Capybara::RSpecMatchers do |session, mode|
 
         it "doesn't wait if wait time is less than timeout" do
           @session.click_link("Change title")
-          using_wait_time 0 do
-            expect(@session).not_to have_title('changed title')
+          using_wait_time 3 do
+            expect(@session).not_to have_title('changed title', wait: 0)
           end
         end
       end

spec/session_spec.rb

@@ -7,4 +7,48 @@ RSpec.describe Capybara::Session do
       Capybara::Session.new(:unknown, { random: "hash"})
     end.to raise_error TypeError, "The second parameter to Session::new should be a rack app if passed."
   end
+
+  context "current_driver" do
+    it "is global when threadsafe false" do
+      Capybara.threadsafe = false
+      Capybara.current_driver = :selenium
+      thread = Thread.new do
+        Capybara.current_driver = :random
+      end
+      thread.join
+      expect(Capybara.current_driver).to eq :random
+    end
+
+    it "is thread specific threadsafe true" do
+      Capybara.threadsafe = true
+      Capybara.current_driver = :selenium
+      thread = Thread.new do
+        Capybara.current_driver = :random
+      end
+      thread.join
+      expect(Capybara.current_driver).to eq :selenium
+    end
+  end
+
+  context "session_name" do
+    it "is global when threadsafe false" do
+      Capybara.threadsafe = false
+      Capybara.session_name = "sess1"
+      thread = Thread.new do
+        Capybara.session_name = "sess2"
+      end
+      thread.join
+      expect(Capybara.session_name).to eq "sess2"
+    end
+
+    it "is thread specific when threadsafe true" do
+      Capybara.threadsafe = true
+      Capybara.session_name = "sess1"
+      thread = Thread.new do
+        Capybara.session_name = "sess2"
+      end
+      thread.join
+      expect(Capybara.session_name).to eq "sess1"
+    end
+  end
 end