Implement tag name selector for FindElementFromElement WebDriver command

components/script/script_thread.rs

@@ -2052,6 +2052,15 @@ impl ScriptThread {
                     reply,
                 )
             },
+            WebDriverScriptCommand::FindElementElementTagName(selector, element_id, reply) => {
+                webdriver_handlers::handle_find_element_element_tag_name(
+                    &*documents,
+                    pipeline_id,
+                    element_id,
+                    selector,
+                    reply,
+                )
+            },
             WebDriverScriptCommand::FindElementElementsCSS(selector, element_id, reply) => {
                 webdriver_handlers::handle_find_element_elements_css(
                     &*documents,

components/script/webdriver_handlers.rs

@@ -259,6 +259,26 @@ pub fn handle_find_element_element_css(
     reply.send(node_id).unwrap();
 }
 
+pub fn handle_find_element_element_tag_name(
+    documents: &Documents,
+    pipeline: PipelineId,
+    element_id: String,
+    selector: String,
+    reply: IpcSender<Result<Option<String>, ()>>,
+) {
+    let node_id = find_node_by_unique_id(documents, pipeline, element_id)
+        .ok_or(())
+        .and_then(|node| match node.downcast::<Element>() {
+            Some(elem) => Ok(elem
+                .GetElementsByTagName(DOMString::from(selector))
+                .elements_iter()
+                .next()),
+            None => Err(()),
+        })
+        .map(|node| node.map(|x| x.upcast::<Node>().unique_id()));
+    reply.send(node_id).unwrap();
+}
+
 pub fn handle_find_element_elements_css(
     documents: &Documents,
     pipeline: PipelineId,

components/script_traits/webdriver_msg.rs

@@ -29,6 +29,7 @@ pub enum WebDriverScriptCommand {
     FindElementsCSS(String, IpcSender<Result<Vec<String>, ()>>),
     FindElementsTagName(String, IpcSender<Result<Vec<String>, ()>>),
     FindElementElementCSS(String, String, IpcSender<Result<Option<String>, ()>>),
+    FindElementElementTagName(String, String, IpcSender<Result<Option<String>, ()>>),
     FindElementElementsCSS(String, String, IpcSender<Result<Option<String>, ()>>),
     FocusElement(String, IpcSender<Result<(), ()>>),
     GetActiveElement(IpcSender<Option<String>>),

components/webdriver_server/lib.rs

@@ -950,21 +950,32 @@ impl Handler {
         element: &WebElement,
         parameters: &LocatorParameters,
     ) -> WebDriverResult<WebDriverResponse> {
-        if parameters.using != LocatorStrategy::CSSSelector {
-            return Err(WebDriverError::new(
-                ErrorStatus::UnsupportedOperation,
-                "Unsupported locator strategy",
-            ));
-        }
-
         let (sender, receiver) = ipc::channel().unwrap();
-        let cmd = WebDriverScriptCommand::FindElementElementCSS(
-            parameters.value.clone(),
-            element.id.clone(),
-            sender,
-        );
 
-        self.browsing_context_script_command(cmd)?;
+        match parameters.using {
+            LocatorStrategy::CSSSelector => {
+                let cmd = WebDriverScriptCommand::FindElementElementCSS(
+                    parameters.value.clone(),
+                    element.id.clone(),
+                    sender,
+                );
+                self.browsing_context_script_command(cmd)?;
+            },
+            LocatorStrategy::TagName => {
+                let cmd = WebDriverScriptCommand::FindElementElementTagName(
+                    parameters.value.clone(),
+                    element.id.clone(),
+                    sender,
+                );
+                self.browsing_context_script_command(cmd)?;
+            },
+            _ => {
+                return Err(WebDriverError::new(
+                    ErrorStatus::UnsupportedOperation,
+                    "Unsupported locator strategy",
+                ));
+            },
+        }
 
         match receiver.recv().unwrap() {
             Ok(value) => {

tests/wpt/metadata/webdriver/tests/find_element_from_element/find.py.ini

@@ -62,9 +62,6 @@
   [test_find_element_partial_link_text[<a href=#>partial link text</a>-k t\]]
     expected: FAIL
 
-  [test_find_element[tag name-a\]]
-    expected: FAIL
-
   [test_xhtml_namespace[partial link text-link text\]]
     expected: FAIL