Test suite: adapt tests after change of semantics for Dogtail.

This is vs #12059, which changes the semantics of Dogtail so that
nodes are searched for on Dogtail::* object creation.

Refs: #12059

features/step_definitions/apt.rb

@@ -86,8 +86,9 @@ When /^I update APT using Synaptic$/ do
     try_for(15*60, :msg => "Took too much time to download the APT data") {
       !$vm.has_process?("/usr/lib/apt/methods/tor+http")
     }
-    if @synaptic.child(roleName: 'dialog', recursive: false).child('Error', roleName: 'icon', retry: false).exist?
-      raise "Updating APT with Synaptic failed."
+    assert_raise(RuntimeError) do
+      @synaptic.child(roleName: 'dialog', recursive: false)
+        .child('Error', roleName: 'icon', retry: false)
     end
     if !$vm.has_process?("synaptic")
       raise "Synaptic process vanished, did it segfault again?"

features/step_definitions/common_steps.rb

@@ -347,8 +347,9 @@ When /^I see the "(.+)" notification(?: after at most (\d+) seconds)?$/ do |titl
   notification_list = gnome_shell.child(
     'No Notifications', roleName: 'label', showingOnly: false
   ).parent.parent
-  notification_list.child(title, roleName: 'label', showingOnly: false)
-    .wait(timeout)
+  try_for(timeout) do
+    notification_list.child?(title, roleName: 'label', showingOnly: false)
+  end
 end
 
 Given /^Tor is ready$/ do
@@ -392,7 +393,7 @@ end
 
 Given /^the Tor Browser has started( in offline mode)?$/ do |offline|
   try_for(60) do
-    @torbrowser.child(roleName: 'frame', recursive: false).exist?
+    @torbrowser.child?(roleName: 'frame', recursive: false)
   end
 end
 
@@ -439,10 +440,10 @@ Given /^all notifications have disappeared$/ do
   gnome_shell = Dogtail::Application.new('gnome-shell')
   retry_action(10, recovery_proc: Proc.new { @screen.type(Sikuli::Key.ESC) }) do
     @screen.click_point(x, y)
-    unless gnome_shell.child('No Notifications', roleName: 'label').exist?
+    unless gnome_shell.child?('No Notifications', roleName: 'label')
       @screen.click('GnomeCloseAllNotificationsButton.png')
     end
-    gnome_shell.child('No Notifications', roleName: 'label').exist?
+    gnome_shell.child?('No Notifications', roleName: 'label')
   end
   @screen.type(Sikuli::Key.ESC)
 end

features/step_definitions/ssh.rb

@@ -141,7 +141,7 @@ end
 
 Then /^I verify the SSH fingerprint for the SFTP server$/ do
   try_for(30) do
-    Dogtail::Application.new('gnome-shell').child('Log In Anyway').exist?
+    Dogtail::Application.new('gnome-shell').child?('Log In Anyway')
   end
   # Here we'd like to click on the button using Dogtail, but something
   # is buggy so let's just use the keyboard.
@@ -151,6 +151,6 @@ end
 Then /^I successfully connect to the SFTP server$/ do
   try_for(60) do
     Dogtail::Application.new('nautilus')
-      .child("#{@sftp_username} on #{@sftp_host}").exist?
+      .child?("#{@sftp_username} on #{@sftp_host}")
   end
 end

features/support/helpers/dogtail.rb

@@ -83,6 +83,12 @@ module Dogtail
       return c
     end
 
+    def child?(*args)
+      !!child(*args)
+    rescue
+      false
+    end
+
     def exist?
       run("dogtail.config.searchCutoffCount = 0")
       run(@find_code)