test(hostrouter): adding test and more documentation

These changes fix a bug where routes were grabbing the routes with less matching path segments,
causing some routes to return the wrong client

BREAKING CHANGE: If apps made workarounds for this bug, then there may be a possibility that the
wrong client is returned for them

COMUI-2914

packages/iframe-coordinator/src/HostRouter.ts

@@ -7,7 +7,7 @@ import {
 
 /**
  * HostRouter is responsible for mapping route paths to
- * corresponding client URls.
+ * corresponding client URLs.
  */
 export class HostRouter {
   private _clients: ClientInfo[];
@@ -17,14 +17,13 @@ export class HostRouter {
       .map(([id, data]) => {
         return parseRegistration(id, data);
       })
-      .sort(
-        (a, b) =>
-          b.assignedRoute.split("/").length - a.assignedRoute.split("/").length,
-      );
+      // Sorts by most path segments in url descending to make sure more specific paths are matched first
+      .sort(byMostPathSegments);
   }
 
   /**
    * Gets the client id and url for the provided route.
+   * Because of the sorting done when instantiated, this will return the target client with the most matching path segments
    *
    * @param route The route to lookup, such as '/foo/bar/baz'
    */
@@ -187,3 +186,10 @@ function applyRoute(urlStr: string, route: string): string {
   }
   return newUrl.toString();
 }
+
+/**
+ * Helper function for sorting clients by length of url path segments descending
+ */
+function byMostPathSegments(a: ClientInfo, b: ClientInfo): number {
+  return b.assignedRoute.split("/").length - a.assignedRoute.split("/").length;
+}

packages/iframe-coordinator/src/specs/HostRouter.spec.ts

@@ -7,7 +7,7 @@ describe("HostRouter", () => {
     hostRouter = new HostRouter({
       route1: {
         url: clientUrl,
-        assignedRoute: "route/one",
+        assignedRoute: "route/one/",
       },
       withRouteSlashes: {
         url: clientUrl,
@@ -23,6 +23,10 @@ describe("HostRouter", () => {
         sandbox: "allow-scripts",
         allow: "microphone *; camera *;",
       },
+      withMoreSpecificity: {
+        url: clientUrl + "/specific",
+        assignedRoute: "route/one/specific",
+      },
     });
   });
 
@@ -92,5 +96,17 @@ describe("HostRouter", () => {
       expect(clientInfo.sandbox).toBe("allow-scripts");
       expect(clientInfo.allow).toBe("microphone *; camera *;");
     });
+
+    it("should return route with more specificity", () => {
+      const clientInfo = hostRouter.getClientTarget("route/one/specific/route");
+      if (!clientInfo) {
+        fail();
+        return;
+      }
+      expect(clientInfo.url).toBe(
+        "http://example.com/#/test/one/specific/route",
+      );
+      expect(clientInfo.id).toBe("withMoreSpecificity");
+    });
   });
 });