client-api: Fix sso_login query param serialization

ruma-client-api/src/r0/session/sso_login.rs

@@ -17,6 +17,7 @@ ruma_api! {
         /// URL to which the homeserver should return the user after completing
         /// authentication with the SSO identity provider.
         #[ruma_api(query)]
+        #[serde(rename = "redirectUrl")]
         pub redirect_url: &'a str,
     }
 
@@ -42,3 +43,22 @@ impl Response {
         Self { location }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use ruma_api::OutgoingRequest;
+
+    use super::Request;
+
+    #[test]
+    fn serialize_sso_login_request_uri() {
+        let req: http::Request<Vec<u8>> = Request { redirect_url: "https://example.com/sso" }
+            .try_into_http_request("https://homeserver.tld", None)
+            .unwrap();
+
+        assert_eq!(
+            req.uri().to_string(),
+            "https://homeserver.tld/_matrix/client/r0/login/sso/redirect?redirectUrl=https%3A%2F%2Fexample.com%2Fsso"
+        );
+    }
+}