Devtools: add automated test for Debugger > Sources (#36401)

This patch adds our first automated test for devtools, covering the
changes in #36164. These tests are not run in CI yet, but you can run
them as follows:

```sh
$ ./mach build --release
$ ./mach test-devtools
```

Testing: this patch adds automated tests!
Start of: #36325

---------

Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: atbrakhi <atbrakhi@igalia.com>
Co-authored-by: Aria Edmonds <aria@ar1as.space>

python/requirements.txt

@@ -37,3 +37,6 @@ types-requests
 
 # For mach package on macOS.
 Mako == 1.2.2
+
+# For devtools tests.
+geckordp == 1.0.3

python/servo/devtools_tests.py

@@ -0,0 +1,150 @@
+# Copyright 2013 The Servo Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+from concurrent.futures import Future
+import logging
+from geckordp.actors.root import RootActor
+from geckordp.actors.descriptors.tab import TabActor
+from geckordp.actors.watcher import WatcherActor
+from geckordp.actors.resources import Resources
+from geckordp.actors.events import Events
+from geckordp.rdp_client import RDPClient
+import http.server
+import os.path
+import socketserver
+import subprocess
+import time
+from threading import Thread
+from typing import Optional
+import unittest
+
+
+class DevtoolsTests(unittest.IsolatedAsyncioTestCase):
+    # /path/to/servo/python/servo
+    script_path = None
+
+    def __init__(self, methodName="runTest"):
+        super().__init__(methodName)
+        self.servoshell = None
+        self.base_url = None
+        self.web_server = None
+        self.web_server_thread = None
+
+    def test_sources_list(self):
+        self.run_servoshell(test_dir=os.path.join(DevtoolsTests.script_path, "devtools_tests/sources"))
+        self.assert_sources_list([f"{self.base_url}/classic.js", f"{self.base_url}/test.html", "https://servo.org/js/load-table.js"])
+
+    def test_sources_list_with_data_no_scripts(self):
+        self.run_servoshell(url="data:text/html,")
+        self.assert_sources_list([])
+
+    def test_sources_list_with_data_empty_inline_script(self):
+        self.run_servoshell(url="data:text/html,<script></script>")
+        self.assert_sources_list([])
+
+    def test_sources_list_with_data_inline_script(self):
+        self.run_servoshell(url="data:text/html,<script>;</script>")
+        self.assert_sources_list(["data:text/html,<script>;</script>"])
+
+    def run_servoshell(self, *, test_dir=None, url=None):
+        if test_dir is None:
+            test_dir = os.path.join(DevtoolsTests.script_path, "devtools_tests")
+        base_url = Future()
+
+        class Handler(http.server.SimpleHTTPRequestHandler):
+            def __init__(self, *args, **kwargs):
+                super().__init__(*args, directory=test_dir, **kwargs)
+
+            def log_message(self, format, *args):
+                # Uncomment this to log requests.
+                # return super().log_message(format, *args)
+                pass
+
+        def server_thread():
+            self.web_server = socketserver.TCPServer(("0.0.0.0", 0), Handler)
+            base_url.set_result(f"http://127.0.0.1:{self.web_server.server_address[1]}")
+            self.web_server.serve_forever()
+
+        # Start a web server for the test.
+        self.web_server_thread = Thread(target=server_thread)
+        self.web_server_thread.start()
+        self.base_url = base_url.result(1)
+
+        # Change this setting if you want to debug Servo.
+        os.environ["RUST_LOG"] = "error,devtools=warn"
+
+        # Run servoshell.
+        if url is None:
+            url = f"{self.base_url}/test.html"
+        self.servoshell = subprocess.Popen(["target/release/servo", "--devtools=6080", url])
+
+        # FIXME: Don’t do this
+        time.sleep(1)
+
+    def tearDown(self):
+        # Terminate servoshell.
+        self.servoshell.terminate()
+
+        # Stop the web server.
+        self.web_server.shutdown()
+        self.web_server_thread.join()
+
+    def assert_sources_list(self, expected_urls):
+        client = RDPClient()
+        client.connect("127.0.0.1", 6080)
+        root = RootActor(client)
+        tabs = root.list_tabs()
+        tab_dict = tabs[0]
+        tab = TabActor(client, tab_dict["actor"])
+        watcher = tab.get_watcher()
+        watcher = WatcherActor(client, watcher["actor"])
+
+        target = Future()
+
+        def on_target(data):
+            if data["target"]["browsingContextID"] == tab_dict["browsingContextID"]:
+                target.set_result(data["target"])
+
+        client.add_event_listener(
+            watcher.actor_id, Events.Watcher.TARGET_AVAILABLE_FORM, on_target,
+        )
+        watcher.watch_targets(WatcherActor.Targets.FRAME)
+
+        done = Future()
+        target = target.result(1)
+
+        def on_source_resource(data):
+            for [resource_type, sources] in data["array"]:
+                try:
+                    self.assertEqual(resource_type, "source")
+                    self.assertEqual([source["url"] for source in sources], expected_urls)
+                    done.set_result(None)
+                except Exception as e:
+                    # Raising here does nothing, for some reason.
+                    # Send the exception back so it can be raised.
+                    done.set_result(e)
+
+        client.add_event_listener(
+            target["actor"],
+            Events.Watcher.RESOURCES_AVAILABLE_ARRAY,
+            on_source_resource,
+        )
+        watcher.watch_resources([Resources.SOURCE])
+
+        result: Optional[Exception] = done.result(1)
+        if result:
+            raise result
+        client.disconnect()
+
+
+def run_tests(script_path):
+    DevtoolsTests.script_path = script_path
+    verbosity = 1 if logging.getLogger().level >= logging.WARN else 2
+    suite = unittest.TestLoader().loadTestsFromTestCase(DevtoolsTests)
+    return unittest.TextTestRunner(verbosity=verbosity).run(suite).wasSuccessful()

python/servo/devtools_tests/sources/classic.js

@@ -0,0 +1 @@
+console.log("external classic");

python/servo/devtools_tests/sources/module.js

@@ -0,0 +1,2 @@
+export default 1;
+console.log("external module");

python/servo/devtools_tests/sources/test.html

@@ -0,0 +1,11 @@
+<!doctype html><meta charset=utf-8>
+<script src="classic.js"></script>
+<script>
+    console.log("inline classic");
+    new Worker("worker.js");
+</script>
+<script type="module">
+    import module from "./module.js";
+    console.log("inline module");
+</script>
+<script src="https://servo.org/js/load-table.js"></script>

python/servo/devtools_tests/sources/worker.js

@@ -0,0 +1 @@
+console.log("external classic worker");

python/servo/testing_commands.py

@@ -19,6 +19,7 @@ import subprocess
 import textwrap
 import json
 
+import servo.devtools_tests
 from servo.post_build_commands import PostBuildCommands
 import wpt
 import wpt.manifestupdate
@@ -326,6 +327,14 @@ class MachCommands(CommandBase):
 
         return 0 if passed else 1
 
+    @Command('test-devtools',
+             description='Run tests for devtools.',
+             category='testing')
+    def test_devtools(self):
+        print("Running devtools tests...")
+        passed = servo.devtools_tests.run_tests(SCRIPT_PATH)
+        return 0 if passed else 1
+
     @Command('test-wpt-failure',
              description='Run the tests harness that verifies that the test failures are reported correctly',
              category='testing',