Support querying numeric HTML properties from elements::Element::prop()

src/elements.rs

@@ -223,20 +223,54 @@ impl Element {
     ///
     /// `Ok(None)` is returned if the element does not have the given property.
     ///
-    /// Boolean properties such as "checked" will be returned as the String "true" or "false".
-    ///
     /// See [13.3 Get Element Property](https://www.w3.org/TR/webdriver1/#get-element-property)
     /// of the WebDriver standard.
     ///
     /// [property]: https://www.ecma-international.org/ecma-262/5.1/#sec-8.12.1
+    ///
+    /// Example:
+    ///
+    /// ```
+    /// # use fantoccini::{ClientBuilder, error, Locator};
+    /// # use serde_json::{json, Number};
+    /// # async fn no_search_results() -> Result<(), error::CmdError> {
+    /// // Define capabilities of client...
+    /// #    let capabilities = json!({})
+    /// #        .as_object()
+    /// #        .unwrap()
+    /// #        .to_owned();
+    /// #
+    /// // Create client...
+    /// # let client = ClientBuilder::native()
+    /// #   .capabilities(capabilities)
+    /// #   .connect("http://127.0.0.1:4444")
+    /// #   .await.unwrap();
+    /// #
+    /// // Perform some kind of search on the website that we don't expect any results from...
+    ///
+    /// let search_matches = client
+    ///     .wait()
+    ///     .for_element(Locator::Css("#search-matches"))
+    ///     .await?;
+    ///
+    /// let num_search_matches = search_matches
+    ///     .prop("childElementCount")
+    ///     .await?
+    ///     .expect("expected there to be some value for childElementCount property")
+    ///     .as_u64()
+    ///     .expect("expected childElementCount to be an integer value");
+    ///
+    /// assert_eq!(num_search_matches, 0);
+    /// #
+    /// #   Ok(())
+    /// # };
+    /// ```
     #[cfg_attr(docsrs, doc(alias = "Get Element Property"))]
-    pub async fn prop(&self, prop: &str) -> Result<Option<String>, error::CmdError> {
+    pub async fn prop(&self, prop: &str) -> Result<Option<Json>, error::CmdError> {
         let cmd = WebDriverCommand::GetElementProperty(self.element.clone(), prop.to_string());
         match self.client.issue(cmd).await? {
-            Json::String(v) => Ok(Some(v)),
-            Json::Bool(b) => Ok(Some(b.to_string())),
             Json::Null => Ok(None),
-            v => Err(error::CmdError::NotW3C(v)),
+            v => Ok(Some(v)),
         }
     }
 
@@ -336,7 +370,7 @@ impl Element {
     #[cfg_attr(docsrs, doc(alias = "outerHTML"))]
     pub async fn html(&self, inner: bool) -> Result<String, error::CmdError> {
         let prop = if inner { "innerHTML" } else { "outerHTML" };
-        Ok(self.prop(prop).await?.unwrap())
+        Ok(self.prop(prop).await?.unwrap().to_string())
     }
 }
 

tests/elements.rs

@@ -46,8 +46,32 @@ async fn element_prop(c: Client, port: u16) -> Result<(), error::CmdError> {
     c.goto(&sample_url).await?;
     let elem = c.find(Locator::Id("checkbox-option-1")).await?;
     assert_eq!(elem.prop("id").await?.unwrap(), "checkbox-option-1");
-    assert_eq!(elem.prop("checked").await?.unwrap(), "false");
+
+    assert_eq!(
+        elem.prop("checked")
+            .await?
+            .expect(
+                "expected checked property to exist on HTML element with ID 'checkbox-option-1'"
+            )
+            .as_bool()
+            .expect("expected checked property to be a boolean value"),
+        false,
+    );
+
     assert!(elem.attr("invalid-property").await?.is_none());
+
+    let elem = c.find(Locator::Id("content")).await?;
+    assert_eq!(
+        elem.prop("childElementCount")
+            .await?
+            .expect(
+                "expected childElementCount property to exist on HTML element with ID 'content'"
+            )
+            .as_u64()
+            .expect("expected childElementCount property to be an integer value"),
+        5,
+    );
+
     Ok(())
 }
 

tests/local.rs

@@ -529,7 +529,7 @@ async fn send_keys_and_clear_input_inner(c: Client, port: u16) -> Result<(), err
             .await?
             .expect("input should have value prop")
             .as_str(),
-        "foobar"
+        Some("foobar")
     );
 
     e.clear().await?;
@@ -538,7 +538,7 @@ async fn send_keys_and_clear_input_inner(c: Client, port: u16) -> Result<(), err
             .await?
             .expect("input should have value prop")
             .as_str(),
-        ""
+        Some("")
     );
 
     let c = e.client();