[Gecko Bug 1456995] enable Service Workers' parent-intercept mode on Nightly

tools/wptrunner/wptrunner/browsers/firefox.py

@@ -153,18 +153,35 @@ def env_options():
 
 def run_info_extras(**kwargs):
 
-    def get_bool_pref(pref):
+    def get_bool_pref_if_exists(pref):
         for key, value in kwargs.get('extra_prefs', []):
             if pref == key:
                 return value.lower() in ('true', '1')
-        return False
+        return None
+
+    def get_bool_pref(pref):
+        pref_value = get_bool_pref_if_exists(pref)
+        return pref_value if pref_value is not None else False
 
     rv = {"e10s": kwargs["gecko_e10s"],
           "wasm": kwargs.get("wasm", True),
           "verify": kwargs["verify"],
           "headless": kwargs.get("headless", False) or "MOZ_HEADLESS" in os.environ,
-          "fission": get_bool_pref("fission.autostart"),
-          "sw-e10s": get_bool_pref("dom.serviceWorkers.parent_intercept")}
+          "fission": get_bool_pref("fission.autostart")}
+
+    # The value of `sw-e10s` defaults to whether the "parent_intercept"
+    # implementation is enabled for the current build. This value, however,
+    # can be overridden by explicitly setting the pref with the `--setpref` CLI
+    # flag, which is checked here. If not supplied, the default value of
+    # `sw-e10s` will be filled in in `RunInfo`'s constructor.
+    #
+    # We can't capture the default value right now because (currently), it
+    # defaults to the value of `nightly_build`, which isn't known until
+    # `RunInfo`'s constructor.
+    sw_e10s_override = get_bool_pref_if_exists("dom.serviceWorkers.parent_intercept")
+    if sw_e10s_override is not None:
+        rv["sw-e10s"] = sw_e10s_override
+
     rv.update(run_info_browser_version(kwargs["binary"]))
     return rv
 

tools/wptrunner/wptrunner/browsers/firefox_android.py

@@ -67,8 +67,7 @@ def env_extras(**kwargs):
 def run_info_extras(**kwargs):
     package = kwargs["package_name"]
     rv = {"e10s": True if package is not None and "geckoview" in package else False,
-          "headless": False,
-          "sw-e10s": False}
+          "headless": False}
     rv.update(run_info_browser_version(kwargs["binary"]))
     return rv
 

tools/wptrunner/wptrunner/wpttest.py

@@ -112,6 +112,18 @@ def __init__(self, metadata_root, product, debug,
         if extras is not None:
             self.update(extras)
 
+        # Until the test harness can understand default pref values,
+        # (https://bugzilla.mozilla.org/show_bug.cgi?id=1577912) this value
+        # should by synchronized with the default pref value indicated in
+        # StaticPrefList.yaml.
+        #
+        # Currently for automation, the pref (and `sw-e10s`) defaults to true in
+        # nightly builds and false otherwise but can be overridden with
+        # `--setpref`. If overridden, the value would be initialized in
+        # `run_info_extras` and be supplied in the `extras` parameter.
+        if "sw-e10s" not in self:
+            self["sw-e10s"] = self.get("nightly_build", False)
+
         self["headless"] = extras.get("headless", False)
         self["webrender"] = enable_webrender