Auto merge of #21213 - servo:android-wpt, r=nox+jgraham

Add some support for WPT tests in an Android emulator through WebDriver

This succeeds on my machine:

`./mach test-wpt --product servodriver --binary etc/run_in_headless_android_emulator.py --binary-arg servo-x86 --binary-arg target/i686-linux-android/release/servo.apk /_mozilla/mozilla/DOMParser.html`

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---
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6 files changed, 256 insertions, 76 deletions

diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index c2b14985f3a..e577307cd1b 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -931,7 +931,12 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             FromCompositorMsg::GetFocusTopLevelBrowsingContext(resp_chan) => {
                 let focus_browsing_context = self.focus_pipeline_id
                     .and_then(|pipeline_id| self.pipelines.get(&pipeline_id))
-                    .map(|pipeline| pipeline.top_level_browsing_context_id);
+                    .map(|pipeline| pipeline.top_level_browsing_context_id)
+                    .filter(|&top_level_browsing_context_id| {
+                        let browsing_context_id =
+                            BrowsingContextId::from(top_level_browsing_context_id);
+                        self.browsing_contexts.contains_key(&browsing_context_id)
+                    });
                 let _ = resp_chan.send(focus_browsing_context);
             }
             FromCompositorMsg::KeyEvent(ch, key, state, modifiers) => {
diff --git a/components/webdriver_server/lib.rs b/components/webdriver_server/lib.rs
index 150a3001c71..47390248dd3 100644
--- a/components/webdriver_server/lib.rs
+++ b/components/webdriver_server/lib.rs
@@ -107,14 +107,14 @@ struct WebDriverSession {
 
     /// Time to wait for injected scripts to run before interrupting them.  A [`None`] value
     /// specifies that the script should run indefinitely.
-    script_timeout: Option<u64>,
+    script_timeout: u64,
 
     /// Time to wait for a page to finish loading upon navigation.
-    load_timeout: Option<u64>,
+    load_timeout: u64,
 
     /// Time to wait for the element location strategy when retrieving elements, and when
     /// waiting for an element to become interactable.
-    implicit_wait_timeout: Option<u64>,
+    implicit_wait_timeout: u64,
 }
 
 impl WebDriverSession {
@@ -127,9 +127,9 @@ impl WebDriverSession {
             browsing_context_id: browsing_context_id,
             top_level_browsing_context_id: top_level_browsing_context_id,
 
-            script_timeout: Some(30_000),
-            load_timeout: Some(300_000),
-            implicit_wait_timeout: Some(0),
+            script_timeout: 30_000,
+            load_timeout: 300_000,
+            implicit_wait_timeout: 0,
         }
     }
 }
@@ -140,7 +140,7 @@ struct Handler {
     resize_timeout: u32,
 }
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 enum ServoExtensionRoute {
     GetPrefs,
     SetPrefs,
@@ -171,7 +171,7 @@ impl WebDriverExtensionRoute for ServoExtensionRoute {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 enum ServoExtensionCommand {
     GetPrefs(GetPrefsParameters),
     SetPrefs(SetPrefsParameters),
@@ -188,7 +188,7 @@ impl WebDriverExtensionCommand for ServoExtensionCommand {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 struct GetPrefsParameters {
     prefs: Vec<String>
 }
@@ -222,7 +222,7 @@ impl ToJson for GetPrefsParameters {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 struct SetPrefsParameters {
     prefs: Vec<(String, PrefValue)>
 }
@@ -371,7 +371,7 @@ impl Handler {
                      -> WebDriverResult<WebDriverResponse> {
         let timeout = self.session()?.load_timeout;
         thread::spawn(move || {
-            thread::sleep(Duration::from_millis(timeout.unwrap()));
+            thread::sleep(Duration::from_millis(timeout));
             let _ = sender.send(LoadStatus::LoadTimeout);
         });
 
@@ -720,9 +720,15 @@ impl Handler {
             .as_mut()
             .ok_or(WebDriverError::new(ErrorStatus::SessionNotCreated, ""))?;
 
-        session.script_timeout = parameters.script;
-        session.load_timeout = parameters.page_load;
-        session.implicit_wait_timeout = parameters.implicit;
+        if let Some(timeout) = parameters.script {
+            session.script_timeout = timeout
+        }
+        if let Some(timeout) = parameters.page_load {
+            session.load_timeout = timeout
+        }
+        if let Some(timeout) = parameters.implicit {
+            session.implicit_wait_timeout = timeout
+        }
 
         Ok(WebDriverResponse::Void)
     }
@@ -750,15 +756,10 @@ impl Handler {
         let func_body = &parameters.script;
         let args_string = "window.webdriverCallback";
 
-        let script = match self.session()?.script_timeout {
-            Some(timeout) => {
-                format!("setTimeout(webdriverTimeout, {}); (function(callback) {{ {} }})({})",
-                        timeout,
-                        func_body,
-                        args_string)
-            }
-            None => format!("(function(callback) {{ {} }})({})", func_body, args_string),
-        };
+        let script = format!("setTimeout(webdriverTimeout, {}); (function(callback) {{ {} }})({})",
+                             self.session()?.script_timeout,
+                             func_body,
+                             args_string);
 
         let (sender, receiver) = ipc::channel().unwrap();
         let command = WebDriverScriptCommand::ExecuteAsyncScript(script, sender);
diff --git a/etc/run_in_headless_android_emulator.py b/etc/run_in_headless_android_emulator.py
index 45e088e0389..32f8e18146f 100755
--- a/etc/run_in_headless_android_emulator.py
+++ b/etc/run_in_headless_android_emulator.py
@@ -48,33 +48,30 @@ def main(avd_name, apk_path, *args):
 
         # Now `adb shell` will work, but `adb install` needs a system service
         # that might still be in the midle of starting and not be responsive yet.
+        wait_for_boot(adb)
 
-        # https://stackoverflow.com/a/38896494/1162888
-        while 1:
-            with terminate_on_exit(
-                adb + ["shell", "getprop", "sys.boot_completed"],
-                stdout=subprocess.PIPE,
-            ) as getprop:
-                stdout, stderr = getprop.communicate()
-                if "1" in stdout:
-                    break
-            time.sleep(1)
-
+        # These steps should happen before application start
         check_call(adb + ["install", "-r", apk_path])
-
-        data_dir = "/sdcard/Android/data/com.mozilla.servo/files"
-        params_file = data_dir + "/android_params"
-
-        check_call(adb + ["shell", "mkdir -p %s" % data_dir])
-        check_call(adb + ["shell", "echo 'servo' > %s" % params_file])
-        for arg in args:
-            check_call(adb + ["shell", "echo %s >> %s" % (shell_quote(arg), params_file)])
+        args = list(args)
+        write_user_stylesheets(adb, args)
+        write_args(adb, args)
 
         check_call(adb + ["shell", "am start com.mozilla.servo/com.mozilla.servo.MainActivity"],
                    stdout=sys.stderr)
 
-        logcat_args = ["RustAndroidGlueStdouterr:D", "*:S", "-v", "raw"]
+        # Start showing logs as soon as the application starts,
+        # in case they say something useful while we wait in subsequent steps.
+        logcat_args = [
+            "--format=raw",  # Print no metadata, only log messages
+            "RustAndroidGlueStdouterr:D",  # Show (debug level) Rust stdio
+            "*:S",  # Hide everything else
+        ]
         with terminate_on_exit(adb + ["logcat"] + logcat_args) as logcat:
+
+            # This step needs to happen after application start
+            forward_webdriver(adb, args)
+
+            # logcat normally won't exit on its own, wait until we get a SIGTERM signal.
             logcat.wait()
 
 
@@ -103,11 +100,90 @@ def terminate_on_exit(*args, **kwargs):
             process.terminate()
 
 
-def check_call(*args, **kwargs):
+# https://stackoverflow.com/a/38896494/1162888
+def wait_for_boot(adb):
+    while 1:
+        with terminate_on_exit(
+            adb + ["shell", "getprop", "sys.boot_completed"],
+            stdout=subprocess.PIPE,
+        ) as getprop:
+            stdout, stderr = getprop.communicate()
+            if "1" in stdout:
+                return
+        time.sleep(1)
+
+
+def call(*args, **kwargs):
     with terminate_on_exit(*args, **kwargs) as process:
-        exit_code = process.wait()
-        if exit_code != 0:
-            sys.exit(exit_code)
+        return process.wait()
+
+
+def check_call(*args, **kwargs):
+    exit_code = call(*args, **kwargs)
+    if exit_code != 0:
+        sys.exit(exit_code)
+
+
+def write_args(adb, args):
+    data_dir = "/sdcard/Android/data/com.mozilla.servo/files"
+    params_file = data_dir + "/android_params"
+
+    check_call(adb + ["shell", "mkdir -p %s" % data_dir])
+    check_call(adb + ["shell", "echo 'servo' > %s" % params_file])
+    for arg in args:
+        check_call(adb + ["shell", "echo %s >> %s" % (shell_quote(arg), params_file)])
+
+
+def write_user_stylesheets(adb, args):
+    data_dir = "/sdcard/Android/data/com.mozilla.servo/files"
+    check_call(adb + ["shell", "mkdir -p %s" % data_dir])
+    for i, (pos, path) in enumerate(extract_args("--user-stylesheet", args)):
+        remote_path = "%s/user%s.css" % (data_dir, i)
+        args[pos] = remote_path
+        check_call(adb + ["push", path, remote_path], stdout=sys.stderr)
+
+
+def forward_webdriver(adb, args):
+    webdriver_port = extract_arg("--webdriver", args)
+    if webdriver_port is not None:
+        # `adb forward` will start accepting TCP connections even if the other side does not.
+        # (If the remote side refuses the connection,
+        # adb will close the local side after accepting it.)
+        # This is incompatible with wptrunner which relies on TCP connection acceptance
+        # to figure out when it can start sending WebDriver requests.
+        #
+        # So wait until the remote side starts listening before setting up the forwarding.
+        wait_for_tcp_server(adb, webdriver_port)
+
+        port = "tcp:%s" % webdriver_port
+        check_call(adb + ["forward", port, port])
+        sys.stderr.write("Forwarding WebDriver port %s to the emulator\n" % webdriver_port)
+
+    split = os.environ.get("EMULATOR_REVERSE_FORWARD_PORTS", "").split(",")
+    ports = [int(part) for part in split if part]
+    for port in ports:
+        port = "tcp:%s" % port
+        check_call(adb + ["reverse", port, port])
+    if ports:
+        sys.stderr.write("Reverse-forwarding ports %s\n" % ", ".join(map(str, ports)))
+
+
+def extract_arg(name, args):
+    for _, arg in extract_args(name, args):
+        return arg
+
+
+def extract_args(name, args):
+    previous_arg_matches = False
+    for i, arg in enumerate(args):
+        if previous_arg_matches:
+            yield i, arg
+        previous_arg_matches = arg == name
+
+
+def wait_for_tcp_server(adb, port):
+    while call(adb + ["shell", "nc -z 127.0.0.1 %s" % port], stdout=sys.stderr) != 0:
+        time.sleep(1)
 
 
 # Copied from Python 3.3+'s shlex.quote()
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index f4092e702be..b0ef2cfa5ce 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -367,6 +367,21 @@ class MachCommands(CommandBase):
         else:
             return ret
 
+    @Command('test-wpt-android',
+             description='Run the web platform test suite in an Android emulator',
+             category='testing',
+             parser=create_parser_wpt)
+    def test_wpt_android(self, release=False, dev=False, binary_args=None, **kwargs):
+        kwargs.update(
+            release=release,
+            dev=dev,
+            product="servodriver",
+            processes=1,
+            binary_args=self.in_android_emulator(release, dev) + (binary_args or []),
+            binary=sys.executable,
+        )
+        return self._test_wpt(**kwargs)
+
     def _test_wpt(self, **kwargs):
         hosts_file_path = path.join(self.context.topdir, 'tests', 'wpt', 'hosts')
         os.environ["hosts_file_path"] = hosts_file_path
@@ -559,28 +574,15 @@ class MachCommands(CommandBase):
     @CommandArgument('--dev', '-d', action='store_true',
                      help='Run the dev build')
     def test_android_startup(self, release, dev):
-        if (release and dev) or not (release or dev):
-            print("Please specify one of --dev or --release.")
-            return 1
-
-        avd = "servo-x86"
-        target = "i686-linux-android"
-        print("Assuming --target " + target)
-
-        env = self.build_env(target=target)
-        assert self.handle_android_target(target)
-        binary_path = self.get_binary_path(release, dev, android=True)
-        apk = binary_path + ".apk"
-
         html = """
             <script>
                 console.log("JavaScript is running!")
             </script>
         """
         url = "data:text/html;base64," + html.encode("base64").replace("\n", "")
-        py = path.join(self.context.topdir, "etc", "run_in_headless_android_emulator.py")
-        args = [sys.executable, py, avd, apk, url]
-        process = subprocess.Popen(args, stdout=subprocess.PIPE, env=env)
+        args = self.in_android_emulator(release, dev)
+        args = [sys.executable] + args + [url]
+        process = subprocess.Popen(args, stdout=subprocess.PIPE)
         try:
             while 1:
                 line = process.stdout.readline()
@@ -593,6 +595,24 @@ class MachCommands(CommandBase):
         finally:
             process.terminate()
 
+    def in_android_emulator(self, release, dev):
+        if (release and dev) or not (release or dev):
+            print("Please specify one of --dev or --release.")
+            sys.exit(1)
+
+        avd = "servo-x86"
+        target = "i686-linux-android"
+        print("Assuming --target " + target)
+
+        env = self.build_env(target=target)
+        os.environ["PATH"] = env["PATH"]
+        assert self.handle_android_target(target)
+        binary_path = self.get_binary_path(release, dev, android=True)
+        apk = binary_path + ".apk"
+
+        py = path.join(self.context.topdir, "etc", "run_in_headless_android_emulator.py")
+        return [py, avd, apk]
+
     @Command('test-jquery',
              description='Run the jQuery test suite',
              category='testing')
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
index 168a576c25a..4111d8b48a8 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/browsers/servodriver.py
@@ -37,7 +37,9 @@ def check_args(**kwargs):
 def browser_kwargs(test_type, run_info_data, **kwargs):
     return {
         "binary": kwargs["binary"],
+        "binary_args": kwargs["binary_args"],
         "debug_info": kwargs["debug_info"],
+        "server_config": kwargs["config"],
         "user_stylesheets": kwargs.get("user_stylesheets"),
     }
 
@@ -71,16 +73,19 @@ def write_hosts_file(config):
 
 class ServoWebDriverBrowser(Browser):
     used_ports = set()
+    init_timeout = 300  # Large timeout for cases where we're booting an Android emulator
 
     def __init__(self, logger, binary, debug_info=None, webdriver_host="127.0.0.1",
-                 user_stylesheets=None):
+                 server_config=None, binary_args=None, user_stylesheets=None):
         Browser.__init__(self, logger)
         self.binary = binary
+        self.binary_args = binary_args or []
         self.webdriver_host = webdriver_host
         self.webdriver_port = None
         self.proc = None
         self.debug_info = debug_info
-        self.hosts_path = write_hosts_file()
+        self.hosts_path = write_hosts_file(server_config)
+        self.server_ports = server_config.ports if server_config else {}
         self.command = None
         self.user_stylesheets = user_stylesheets if user_stylesheets else []
 
@@ -91,10 +96,16 @@ class ServoWebDriverBrowser(Browser):
         env = os.environ.copy()
         env["HOST_FILE"] = self.hosts_path
         env["RUST_BACKTRACE"] = "1"
+        env["EMULATOR_REVERSE_FORWARD_PORTS"] = ",".join(
+            str(port)
+            for _protocol, ports in self.server_ports.items()
+            for port in ports
+            if port
+        )
 
         debug_args, command = browser_command(
             self.binary,
-            [
+            self.binary_args + [
                 "--hard-fail",
                 "--webdriver", str(self.webdriver_port),
                 "about:blank",
@@ -151,9 +162,10 @@ class ServoWebDriverBrowser(Browser):
 
     def cleanup(self):
         self.stop()
-        shutil.rmtree(os.path.dirname(self.hosts_file))
+        os.remove(self.hosts_path)
 
     def executor_browser(self):
         assert self.webdriver_port is not None
         return ExecutorBrowser, {"webdriver_host": self.webdriver_host,
-                                 "webdriver_port": self.webdriver_port}
+                                 "webdriver_port": self.webdriver_port,
+                                 "init_timeout": self.init_timeout}
diff --git a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
index f649a75cd93..896aeb39eff 100644
--- a/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
+++ b/tests/wpt/web-platform-tests/tools/wptrunner/wptrunner/executors/executorservodriver.py
@@ -6,13 +6,16 @@ import time
 import traceback
 
 from .base import (Protocol,
+                   BaseProtocolPart,
                    RefTestExecutor,
                    RefTestImplementation,
                    TestharnessExecutor,
                    strip_server)
 from ..testrunner import Stop
+from ..webdriver_server import wait_for_service
 
 webdriver = None
+ServoCommandExtensions = None
 
 here = os.path.join(os.path.split(__file__)[0])
 
@@ -23,20 +26,76 @@ def do_delayed_imports():
     global webdriver
     import webdriver
 
+    global ServoCommandExtensions
+    class ServoCommandExtensions(object):
+        def __init__(self, session):
+            self.session = session
+
+        @webdriver.client.command
+        def get_prefs(self, *prefs):
+            body = {"prefs": list(prefs)}
+            return self.session.send_session_command("POST", "servo/prefs/get", body)
+
+        @webdriver.client.command
+        def set_prefs(self, prefs):
+            body = {"prefs": prefs}
+            return self.session.send_session_command("POST", "servo/prefs/set", body)
+
+        @webdriver.client.command
+        def reset_prefs(self, *prefs):
+            body = {"prefs": list(prefs)}
+            return self.session.send_session_command("POST", "servo/prefs/reset", body)
+
+        def change_prefs(self, old_prefs, new_prefs):
+            # Servo interprets reset with an empty list as reset everything
+            if old_prefs:
+                self.reset_prefs(*old_prefs.keys())
+            self.set_prefs({k: parse_pref_value(v) for k, v in new_prefs.items()})
+
+
+# See parse_pref_from_command_line() in components/config/opts.rs
+def parse_pref_value(value):
+    if value == "true":
+        return True
+    if value == "false":
+        return False
+    try:
+        return float(value)
+    except ValueError:
+        return value
+
+
+class ServoBaseProtocolPart(BaseProtocolPart):
+    def execute_script(self, script, async=False):
+        pass
+
+    def set_timeout(self, timeout):
+        pass
+
+    def wait(self):
+        pass
+
+    def set_window(self, handle):
+        pass
+
 
 class ServoWebDriverProtocol(Protocol):
+    implements = [ServoBaseProtocolPart]
+
     def __init__(self, executor, browser, capabilities, **kwargs):
         do_delayed_imports()
         Protocol.__init__(self, executor, browser)
         self.capabilities = capabilities
         self.host = browser.webdriver_host
         self.port = browser.webdriver_port
+        self.init_timeout = browser.init_timeout
         self.session = None
 
     def connect(self):
         """Connect to browser via WebDriver."""
-        self.session = webdriver.Session(self.host, self.port,
-                                         extension=webdriver.servo.ServoCommandExtensions)
+        wait_for_service((self.host, self.port), timeout=self.init_timeout)
+
+        self.session = webdriver.Session(self.host, self.port, extension=ServoCommandExtensions)
         self.session.start()
 
     def after_connect(self):
@@ -70,11 +129,6 @@ class ServoWebDriverProtocol(Protocol):
                 self.logger.error(traceback.format_exc(e))
                 break
 
-    def on_environment_change(self, old_environment, new_environment):
-        #Unset all the old prefs
-        self.session.extension.reset_prefs(*old_environment.get("prefs", {}).keys())
-        self.session.extension.set_prefs(new_environment.get("prefs", {}))
-
 
 class ServoWebDriverRun(object):
     def __init__(self, func, session, url, timeout, current_timeout=None):
@@ -174,6 +228,12 @@ class ServoWebDriverTestharnessExecutor(TestharnessExecutor):
         session.back()
         return result
 
+    def on_environment_change(self, new_environment):
+        self.protocol.session.extension.change_prefs(
+            self.last_environment.get("prefs", {}),
+            new_environment.get("prefs", {})
+        )
+
 
 class TimeoutError(Exception):
     pass
@@ -240,3 +300,9 @@ class ServoWebDriverRefTestExecutor(RefTestExecutor):
         session.url = url
         session.execute_async_script(self.wait_script)
         return session.screenshot()
+
+    def on_environment_change(self, new_environment):
+        self.protocol.session.extension.change_prefs(
+            self.last_environment.get("prefs", {}),
+            new_environment.get("prefs", {})
+        )