YusukeIwaki · YusukeIwaki · Dec 26, 2020 · Dec 26, 2020
diff --git a/lib/puppeteer/launcher/chrome.rb b/lib/puppeteer/launcher/chrome.rb
@@ -105,6 +105,9 @@ def initialize(chrome_arg_options)
           '--enable-automation',
           '--password-store=basic',
           '--use-mock-keychain',
+          # TODO(sadym): remove '--enable-blink-features=IdleDetection'
+          # once IdleDetection is turned on by default.
+          '--enable-blink-features=IdleDetection',
         ]
 
         if chrome_arg_options.user_data_dir

diff --git a/lib/puppeteer/page.rb b/lib/puppeteer/page.rb
@@ -829,6 +829,21 @@ def emulate_timezone(timezone_id)
     end
   end
 
+  # @param is_user_active [Boolean]
+  # @param is_screen_unlocked [Boolean]
+  def emulate_idle_state(is_user_active: nil, is_screen_unlocked: nil)
+    overrides = {
+      isUserActive: is_user_active,
+      isScreenUnlocked: is_screen_unlocked,
+    }.compact
+
+    if overrides.empty?
+      @client.send_message('Emulation.clearIdleOverride')
+    else
+      @client.send_message('Emulation.setIdleOverride', overrides)
+    end
+  end
+
   # @param viewport [Viewport]
   def viewport=(viewport)
     needs_reload = @emulation_manager.emulate_viewport(viewport)

diff --git a/spec/integration/idle_override_spec.rb b/spec/integration/idle_override_spec.rb
@@ -0,0 +1,71 @@
+require 'spec_helper'
+
+RSpec.describe 'Emulate idle state' do
+  def idle_state_for(page)
+    state_element = page.S('#state')
+    page.evaluate('(element) => element.innerText', state_element)
+  end
+
+  sinatra do
+    get('/idle-detector.html') do
+      <<~HTML
+      <!DOCTYPE html>
+      <div id="state"></div>
+      <script>
+        const elState = document.querySelector('#state');
+        function setState(msg) {
+          elState.textContent = msg;
+        }
+        async function main() {
+          const controller = new AbortController();
+          const signal = controller.signal;
+          const idleDetector = new IdleDetector({
+            threshold: 60000,
+            signal,
+          });
+          idleDetector.addEventListener('change', () => {
+            const userState = idleDetector.userState;
+            const screenState = idleDetector.screenState;
+            setState(`Idle state: ${userState}, ${screenState}.`);
+          });
+          idleDetector.start();
+        }
+        main();
+      </script>
+      HTML
+    end
+  end
+
+  it_fails_firefox 'changing idle state emulation causes change of the IdleDetector state', browser_context: :incognit do
+    page.browser_context.override_permissions("http://127.0.0.1:4567/idle-detector.html", ['idle-detection'])
+    page.goto('http://127.0.0.1:4567/idle-detector.html')
+
+    # Store initial state, as soon as it is not guaranteed to be `active, unlocked`.
+    initial_state = idle_state_for(page)
+
+    # Emulate Idle states and verify IdleDetector updates state accordingly.
+    page.emulate_idle_state(is_user_active: false, is_screen_unlocked: false)
+    expect(idle_state_for(page)).to eq('Idle state: idle, locked.')
+
+    page.emulate_idle_state(is_user_active: true, is_screen_unlocked: false)
+    expect(idle_state_for(page)).to eq('Idle state: active, locked.')
+
+    page.emulate_idle_state(is_user_active: true, is_screen_unlocked: true)
+    expect(idle_state_for(page)).to eq('Idle state: active, unlocked.')
+
+    page.emulate_idle_state(is_user_active: false, is_screen_unlocked: true)
+    expect(idle_state_for(page)).to eq('Idle state: idle, unlocked.')
+
+    # Remove Idle emulation and verify IdleDetector is in initial state.
+    page.emulate_idle_state
+    expect(idle_state_for(page)).to eq(initial_state)
+
+    # Emulate idle state again after removing emulation.
+    page.emulate_idle_state(is_user_active: false, is_screen_unlocked: false)
+    expect(idle_state_for(page)).to eq('Idle state: idle, locked.')
+
+    # Remove emulation second time.
+    page.emulate_idle_state
+    expect(idle_state_for(page)).to eq(initial_state)
+  end
+end