Function setUrlParams removes URL array params

This change extends setUrlParams when changing a URL by having it
remove the parameters when arrays are empty.

Now it is possible to remove the array parameters of the URL:

https://gitlab.com/test?labels[]=foo&labels[]=bar

By adding `{ labels: [] }`, to obtain:

https://gitlab.com/test

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

@@ -484,13 +484,17 @@ export const setUrlParams = (
       searchParams.delete(key);
     } else if (Array.isArray(params[key])) {
       const keyName = railsArraySyntax ? `${key}[]` : key;
-      params[key].forEach((val, idx) => {
-        if (idx === 0) {
-          searchParams.set(keyName, val);
-        } else {
-          searchParams.append(keyName, val);
-        }
-      });
+      if (params[key].length === 0) {
+        searchParams.delete(keyName);
+      } else {
+        params[key].forEach((val, idx) => {
+          if (idx === 0) {
+            searchParams.set(keyName, val);
+          } else {
+            searchParams.append(keyName, val);
+          }
+        });
+      }
     } else {
       searchParams.set(key, params[key]);
     }

spec/frontend/lib/utils/url_utility_spec.js

@@ -798,15 +798,29 @@ describe('URL utility', () => {
       );
     });
 
-    it('handles arrays properly', () => {
+    it('adds parameters from arrays', () => {
       const url = 'https://gitlab.com/test';
 
-      expect(urlUtils.setUrlParams({ label_name: ['foo', 'bar'] }, url)).toEqual(
-        'https://gitlab.com/test?label_name=foo&label_name=bar',
+      expect(urlUtils.setUrlParams({ labels: ['foo', 'bar'] }, url)).toEqual(
+        'https://gitlab.com/test?labels=foo&labels=bar',
       );
     });
 
-    it('handles arrays properly when railsArraySyntax=true', () => {
+    it('removes parameters from empty arrays', () => {
+      const url = 'https://gitlab.com/test?labels=foo&labels=bar';
+
+      expect(urlUtils.setUrlParams({ labels: [] }, url)).toEqual('https://gitlab.com/test');
+    });
+
+    it('removes parameters from empty arrays while keeping other parameters', () => {
+      const url = 'https://gitlab.com/test?labels=foo&labels=bar&unrelated=unrelated';
+
+      expect(urlUtils.setUrlParams({ labels: [] }, url)).toEqual(
+        'https://gitlab.com/test?unrelated=unrelated',
+      );
+    });
+
+    it('adds parameters from arrays when railsArraySyntax=true', () => {
       const url = 'https://gitlab.com/test';
 
       expect(urlUtils.setUrlParams({ labels: ['foo', 'bar'] }, url, false, true)).toEqual(
@@ -814,6 +828,14 @@ describe('URL utility', () => {
       );
     });
 
+    it('removes parameters from empty arrays when railsArraySyntax=true', () => {
+      const url = 'https://gitlab.com/test?labels%5B%5D=foo&labels%5B%5D=bar';
+
+      expect(urlUtils.setUrlParams({ labels: [] }, url, false, true)).toEqual(
+        'https://gitlab.com/test',
+      );
+    });
+
     it('decodes URI when decodeURI=true', () => {
       const url = 'https://gitlab.com/test';