fix explode query check of mockapi for routes test case (#742)

* fix explode query check in routes test case

* changeset

.changeset/thin-radios-help.md

@@ -0,0 +1,5 @@
+---
+"@azure-tools/cadl-ranch-specs": patch
+---
+
+fix explode query check of mockapi for routes test case

packages/cadl-ranch-specs/http/routes/mockapi.ts

@@ -7,8 +7,25 @@ function defineUri(uri: string) {
   const url = new URL("http://example.com" + uri);
   return passOnSuccess(
     mockapi.get(url.pathname, (req) => {
+      const queryMap = new Map<string, string | string[]>();
       for (const [key, value] of url.searchParams.entries()) {
-        req.expect.containsQueryParam(key, value);
+        if (queryMap.has(key)) {
+          const existing = queryMap.get(key)!;
+          if (Array.isArray(existing)) {
+            existing.push(value);
+          } else {
+            queryMap.set(key, [existing, value]);
+          }
+        } else {
+          queryMap.set(key, value);
+        }
+      }
+      for (const [key, value] of queryMap.entries()) {
+        if (Array.isArray(value)) {
+          req.expect.containsQueryParam(key, value, "multi");
+        } else {
+          req.expect.containsQueryParam(key, value);
+        }
       }
       for (const param of Object.keys(req.query)) {
         if (!url.searchParams.has(param)) {