Support ./wpt run --channel=preview safari (#13460)

This mostly to avoid the lengthy argument currently required:
`--webdriver-binary "/Applications/Safari Technology Preview.app/Contents/MacOS/safaridriver"`

Using `--browser-channel=preview` and the product `safari_webdriver`
also works.

docs/_running-tests/safari.md

@@ -22,7 +22,7 @@ Now, run the tests using the `safari` product:
 ```
 
 This will use the `safaridriver` found on the path, which will be stable Safari.
-To run Safari Technology Preview instead, use the `--webdriver-binary` argument:
+To run Safari Technology Preview instead, use the `--channel=preview` argument:
 ```
-./wpt run --webdriver-binary "/Applications/Safari Technology Preview.app/Contents/MacOS/safaridriver" safari [test_list]
+./wpt run --channel=preview safari [test_list]
 ```

tools/wpt/browser.py

@@ -41,7 +41,7 @@ def find_binary(self, venv_path=None, channel=None):
         return NotImplemented
 
     @abstractmethod
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         """Find the binary of the WebDriver."""
         return NotImplemented
 
@@ -211,7 +211,7 @@ def find_certutil(self):
             return None
         return path
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("geckodriver")
 
     def get_version_and_channel(self, binary):
@@ -387,7 +387,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         raise NotImplementedError
 
     def install_webdriver(self, dest=None, channel=None):
@@ -441,7 +441,7 @@ def platform_string(self):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("chromedriver")
 
     def install_webdriver(self, dest=None, channel=None):
@@ -489,7 +489,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("chromedriver")
 
     def install_webdriver(self, dest=None, channel=None):
@@ -541,7 +541,7 @@ def platform_string(self):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("operadriver")
 
     def install_webdriver(self, dest=None, channel=None):
@@ -584,7 +584,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("MicrosoftWebDriver")
 
     def install_webdriver(self, dest=None, channel=None):
@@ -610,7 +610,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return find_executable("IEDriverServer.exe")
 
     def install_webdriver(self, dest=None, channel=None):
@@ -635,8 +635,11 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
-        return find_executable("safaridriver")
+    def find_webdriver(self, channel=None):
+        path = None
+        if channel == "preview":
+            path = "/Applications/Safari Technology Preview.app/Contents/MacOS"
+        return find_executable("safaridriver", path)
 
     def install_webdriver(self, dest=None, channel=None):
         raise NotImplementedError
@@ -695,7 +698,7 @@ def find_binary(self, venv_path=None, channel=None):
             path = find_executable("servo")
         return path
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return None
 
     def install_webdriver(self, dest=None, channel=None):
@@ -719,7 +722,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venev_path=None, channel=None):
         raise NotImplementedError
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         raise NotImplementedError
 
     def install_webdriver(self, dest=None, channel=None):
@@ -741,7 +744,7 @@ def install(self, dest=None, channel=None):
     def find_binary(self, venv_path=None, channel=None):
         return None
 
-    def find_webdriver(self):
+    def find_webdriver(self, channel=None):
         return None
 
     def install_webdriver(self, dest=None, channel=None):

tools/wpt/install.py

@@ -6,6 +6,8 @@
 latest_channels = {
     'firefox': 'nightly',
     'chrome': 'dev',
+    'safari': 'preview',
+    'safari_webdriver': 'preview',
     'servo': 'nightly'
 }
 

tools/wpt/run.py

@@ -371,7 +371,7 @@ def install(self, venv, channel=None):
 
     def setup_kwargs(self, kwargs):
         if kwargs["webdriver_binary"] is None:
-            webdriver_binary = self.browser.find_webdriver()
+            webdriver_binary = self.browser.find_webdriver(channel=kwargs["browser_channel"])
 
             if webdriver_binary is None:
                 raise WptrunError("Unable to locate safaridriver binary")