[e2e]Add e2e test for deleting custom network (#17254)

* add test for deleting added custom network

* update code because of failing on firefox browser

* changing steps for adding custom network

* chage code for custom network

test/e2e/tests/add-custom-network.spec.js

@@ -147,4 +147,55 @@ describe('Custom network', function () {
       },
     );
   });
+  it('Add a custom network and then delete that same network', async function () {
+    await withFixtures(
+      {
+        fixtures: new FixtureBuilder()
+          .withPreferencesController({
+            frequentRpcListDetail: [
+              {
+                rpcUrl: networkURL,
+                chainId: chainID,
+                ticker: currencySYMBOL,
+                nickname: networkNAME,
+                rpcPrefs: {},
+              },
+            ],
+          })
+          .build(),
+        ganacheOptions,
+        title: this.test.title,
+      },
+      async ({ driver }) => {
+        await driver.navigate();
+        await driver.fill('#password', 'correct horse battery staple');
+        await driver.press('#password', driver.Key.ENTER);
+
+        await driver.clickElement('.account-menu__icon');
+        await driver.clickElement({ text: 'Settings', tag: 'div' });
+        await driver.clickElement({ text: 'Networks', tag: 'div' });
+
+        const arbitrumNetwork = await driver.clickElement({
+          text: `Arbitrum One`,
+          tag: 'div',
+        });
+
+        await driver.clickElement({
+          tag: 'button',
+          text: 'Delete',
+        });
+
+        await driver.findElement('.modal-container__footer');
+        // should be deleted from the modal shown again to complete  deletion custom network
+        await driver.clickElement({
+          tag: 'button',
+          text: 'Delete',
+        });
+
+        // it checks if custom network is delete
+        const existNetwork = await driver.isElementPresent(arbitrumNetwork);
+        assert.equal(existNetwork, false, 'Network is not deleted');
+      },
+    );
+  });
 });