Make startup.js to account for the param orders

When startup.js checks whether a API call has been prefetched or not,
it uses a path string (e.g., /path?a=1&c=2) but this check can fail
when the params listed in the path string in a different order.

This MR uses options.sort for mergeUrlParams
to sort the params in the requested path string to fix the above issue.

app/assets/javascripts/lib/utils/axios_startup_calls.js

@@ -7,7 +7,7 @@ const removeGitLabUrl = url => url.replace(gon.gitlab_url, '');
 
 const getFullUrl = req => {
   const url = removeGitLabUrl(req.url);
-  return mergeUrlParams(req.params || {}, url);
+  return mergeUrlParams(req.params || {}, url, { sort: true });
 };
 
 const handleStartupCall = async ({ fetchCall }, req) => {

spec/frontend/lib/utils/axios_startup_calls_spec.js

@@ -111,21 +111,44 @@ describe('setupAxiosStartupCalls', () => {
     });
   });
 
-  it('removes GitLab Base URL from startup call', async () => {
-    const oldGon = window.gon;
-    window.gon = { gitlab_url: 'https://example.org/gitlab' };
-
-    window.gl.startup_calls = {
-      '/startup': {
-        fetchCall: mockFetchCall(200),
-      },
-    };
-    setupAxiosStartupCalls(axios);
+  describe('startup call', () => {
+    let oldGon;
+
+    beforeEach(() => {
+      oldGon = window.gon;
+      window.gon = { gitlab_url: 'https://example.org/gitlab' };
+    });
+
+    afterEach(() => {
+      window.gon = oldGon;
+    });
 
-    const { data } = await axios.get('https://example.org/gitlab/startup');
+    it('removes GitLab Base URL from startup call', async () => {
+      window.gl.startup_calls = {
+        '/startup': {
+          fetchCall: mockFetchCall(200),
+        },
+      };
+      setupAxiosStartupCalls(axios);
 
-    expect(data).toEqual(STARTUP_JS_RESPONSE);
+      const { data } = await axios.get('https://example.org/gitlab/startup');
 
-    window.gon = oldGon;
+      expect(data).toEqual(STARTUP_JS_RESPONSE);
+    });
+
+    it('sorts the params in the requested API url', async () => {
+      window.gl.startup_calls = {
+        '/startup?alpha=true&bravo=true': {
+          fetchCall: mockFetchCall(200),
+        },
+      };
+      setupAxiosStartupCalls(axios);
+
+      // Use a full url instead of passing options = { params: { ... } } to axios.get
+      // to ensure the params are listed in the specified order.
+      const { data } = await axios.get('https://example.org/gitlab/startup?bravo=true&alpha=true');
+
+      expect(data).toEqual(STARTUP_JS_RESPONSE);
+    });
   });
 });