Fix @run-at default for GreaseMonkey

3 files changed, 50 insertions, 0 deletions

diff --git a/doc/changelog.asciidoc b/doc/changelog.asciidoc
index 93a85866b..d57698df7 100644
--- a/doc/changelog.asciidoc
+++ b/doc/changelog.asciidoc
@@ -93,6 +93,10 @@ Fixed
   properly.
 - The "try again" button on error pages now works correctly with JavaScript
   disabled.
+- If a GreaseMonkey script doesn't have a "@run-at" comment, qutebrowser
+  accidentally treated that as "@run-at document-idle". However, other
+  GreaseMonkey implementations default to "@run-at document-end" instead, which
+  is what qutebrowser now does, too.
 
 [[v2.0.2]]
 v2.0.2 (2021-02-04)
diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index 439d99570..450d68751 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -1099,6 +1099,7 @@ class _WebEngineScripts(QObject):
 
         for script in scripts:
             new_script = QWebEngineScript()
+
             try:
                 world = int(script.jsworld)
                 if not 0 <= world <= qtutils.MAX_WORLD_ID:
@@ -1116,6 +1117,17 @@ class _WebEngineScripts(QObject):
                         f": {script.jsworld}")
                     continue
             new_script.setWorldId(world)
+
+            # Corresponds to "@run-at document-end" which is the default according to
+            # https://wiki.greasespot.net/Metadata_Block#.40run-at - however,
+            # QtWebEngine uses QWebEngineScript.Deferred (@run-at document-idle) as
+            # default.
+            #
+            # NOTE that this needs to be done before setSourceCode, so that
+            # QtWebEngine's parsing of GreaseMonkey tags will override it if there is a
+            # @run-at comment.
+            new_script.setInjectionPoint(QWebEngineScript.DocumentReady)
+
             new_script.setSourceCode(script.code())
             new_script.setName(f"GM-{script.name}")
             new_script.setRunsOnSubFrames(script.runs_on_sub_frames)
diff --git a/tests/unit/browser/webengine/test_webenginetab.py b/tests/unit/browser/webengine/test_webenginetab.py
index 7827c379b..2c792f80e 100644
--- a/tests/unit/browser/webengine/test_webenginetab.py
+++ b/tests/unit/browser/webengine/test_webenginetab.py
@@ -20,6 +20,7 @@
 """Test webenginetab."""
 
 import logging
+import textwrap
 
 import pytest
 QtWebEngineWidgets = pytest.importorskip("PyQt5.QtWebEngineWidgets")
@@ -116,6 +117,39 @@ class TestWebengineScripts:
         script = collection.toList()[-1]
         assert script.injectionPoint() == QWebEngineScript.DocumentReady
 
+    @pytest.mark.parametrize('run_at, expected', [
+        # UserScript::DocumentElementCreation
+        ('document-start', QWebEngineScript.DocumentCreation),
+        # UserScript::DocumentLoadFinished
+        ('document-end', QWebEngineScript.DocumentReady),
+        # UserScript::AfterLoad
+        ('document-idle', QWebEngineScript.Deferred),
+        # default according to https://wiki.greasespot.net/Metadata_Block#.40run-at
+        (None, QWebEngineScript.DocumentReady),
+    ])
+    def test_run_at_values(self, webengine_scripts, run_at, expected):
+        if run_at is None:
+            script = """
+                // ==UserScript==
+                // @name qutebrowser test userscript
+                // ==/UserScript==
+            """
+        else:
+            script = f"""
+                // ==UserScript==
+                // @name qutebrowser test userscript
+                // @run-at {run_at}
+                // ==/UserScript==
+            """
+
+        script = textwrap.dedent(script.lstrip('\n'))
+        scripts = [greasemonkey.GreasemonkeyScript.parse(script)]
+        webengine_scripts._inject_greasemonkey_scripts(scripts)
+
+        collection = webengine_scripts._widget.page().scripts()
+        script = collection.toList()[-1]
+        assert script.injectionPoint() == expected
+
 
 def test_notification_permission_workaround():
     """Make sure the value for QWebEnginePage::Notifications is correct."""