From 689840dcbe028b23748ec1c04a9a6f0e50bfacf7 Mon Sep 17 00:00:00 2001
From: Jonathan Ash <jonathan-ash@users.noreply.github.com>
Date: Wed, 16 Feb 2022 10:52:17 +0000
Subject: [PATCH] Added the ability for SidebarSubmenuItem to use external
 links via "to" property

Signed-off-by: Jonathan Ash <jonathan-ash@users.noreply.github.com>
---
 .changeset/unlucky-queens-brush.md            |  5 ++++
 .../src/layout/Sidebar/Bar.test.tsx           | 26 +++++++++++++++++++
 .../src/layout/Sidebar/SidebarSubmenuItem.tsx |  7 +++--
 .../src/layout/Sidebar/utils.test.ts          | 14 +++++++++-
 .../src/layout/Sidebar/utils.ts               |  2 ++
 5 files changed, 51 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/unlucky-queens-brush.md

diff --git a/.changeset/unlucky-queens-brush.md b/.changeset/unlucky-queens-brush.md
new file mode 100644
index 0000000000..c080856246
--- /dev/null
+++ b/.changeset/unlucky-queens-brush.md
@@ -0,0 +1,5 @@
+---
+'@backstage/core-components': patch
+---
+
+Added ability for SidebarSubmenuItem to handle external links correctly via the "to" prop
diff --git a/packages/core-components/src/layout/Sidebar/Bar.test.tsx b/packages/core-components/src/layout/Sidebar/Bar.test.tsx
index 89133997f9..fc42e7a94e 100644
--- a/packages/core-components/src/layout/Sidebar/Bar.test.tsx
+++ b/packages/core-components/src/layout/Sidebar/Bar.test.tsx
@@ -46,6 +46,11 @@ async function renderScalableSidebar() {
         <SidebarItem icon={MenuBookIcon} onClick={() => {}} text="Catalog">
           <SidebarSubmenu title="Catalog">
             <SidebarSubmenuItem title="Tools" to="/1" icon={BuildRoundedIcon} />
+            <SidebarSubmenuItem
+              title="External Link"
+              to="https://backstage.io/"
+              icon={BuildRoundedIcon}
+            />
             <SidebarSubmenuItem
               title="Misc"
               to="/6"
@@ -59,6 +64,10 @@ async function renderScalableSidebar() {
                   title: 'dropdown item 2',
                   to: '/dropdownitemlink2',
                 },
+                {
+                  title: 'dropdown item 3',
+                  to: 'https://backstage.io/',
+                },
               ]}
             />
           </SidebarSubmenu>
@@ -112,5 +121,22 @@ describe('Sidebar', () => {
         '/dropdownitemlink',
       );
     });
+
+    it('Submenu item renders an external link when `to` value is provided', async () => {
+      userEvent.hover(screen.getByTestId('item-with-submenu'));
+      expect(screen.getByText('External Link').closest('a')).toHaveAttribute(
+        'href',
+        'https://backstage.io/',
+      );
+    });
+
+    it('Dropdown item in submenu renders an external link when `to` value is provided', async () => {
+      userEvent.hover(screen.getByTestId('item-with-submenu'));
+      userEvent.click(screen.getByText('Misc'));
+      expect(screen.getByText('dropdown item 3').closest('a')).toHaveAttribute(
+        'href',
+        'https://backstage.io/',
+      );
+    });
   });
 });
diff --git a/packages/core-components/src/layout/Sidebar/SidebarSubmenuItem.tsx b/packages/core-components/src/layout/Sidebar/SidebarSubmenuItem.tsx
index 1ede5f887e..1d697ead14 100644
--- a/packages/core-components/src/layout/Sidebar/SidebarSubmenuItem.tsx
+++ b/packages/core-components/src/layout/Sidebar/SidebarSubmenuItem.tsx
@@ -30,6 +30,8 @@ import ArrowDropDownIcon from '@material-ui/icons/ArrowDropDown';
 import ArrowDropUpIcon from '@material-ui/icons/ArrowDropUp';
 import { SidebarItemWithSubmenuContext } from './config';
 import { isLocationMatch } from './utils';
+import { Link as BackstageLink } from '../../';
+import { isExternalLink } from './utils';
 
 const useStyles = makeStyles<BackstageTheme>(theme => ({
   item: {
@@ -133,6 +135,7 @@ export const SidebarSubmenuItem = (props: SidebarSubmenuItemProps) => {
   const handleClickDropdown = () => {
     setShowDropDown(!showDropDown);
   };
+
   if (dropdownItems !== undefined) {
     dropdownItems.some(item => {
       const resolvedPath = resolvePath(item.to);
@@ -163,7 +166,7 @@ export const SidebarSubmenuItem = (props: SidebarSubmenuItemProps) => {
           <div className={classes.dropdown}>
             {dropdownItems.map((object, key) => (
               <Link
-                component={NavLink}
+                component={isExternalLink(object.to) ? BackstageLink : NavLink}
                 to={object.to}
                 underline="none"
                 className={classes.dropdownItem}
@@ -185,7 +188,7 @@ export const SidebarSubmenuItem = (props: SidebarSubmenuItemProps) => {
   return (
     <div className={classes.itemContainer}>
       <Link
-        component={NavLink}
+        component={isExternalLink(to) ? BackstageLink : NavLink}
         to={to}
         underline="none"
         className={classnames(
diff --git a/packages/core-components/src/layout/Sidebar/utils.test.ts b/packages/core-components/src/layout/Sidebar/utils.test.ts
index b08dcda0fc..34d418096f 100644
--- a/packages/core-components/src/layout/Sidebar/utils.test.ts
+++ b/packages/core-components/src/layout/Sidebar/utils.test.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 import { Location, Path } from 'history';
-import { isLocationMatch } from './utils';
+import { isExternalLink, isLocationMatch } from './utils';
 
 describe('isLocationMatching', () => {
   let currentLocation: Location;
@@ -96,3 +96,15 @@ describe('isLocationMatching', () => {
     expect(isLocationMatch(currentLocation, toLocation)).toBe(true);
   });
 });
+
+describe('isExternalLink', () => {
+  beforeEach(() => expect.hasAssertions());
+
+  it('should return true if provided with an external link', () => {
+    expect(isExternalLink('https://backstage.io/')).toEqual(true);
+  });
+
+  it('should return false if provided with a relative link', () => {
+    expect(isExternalLink('catalog')).toEqual(false);
+  });
+});
diff --git a/packages/core-components/src/layout/Sidebar/utils.ts b/packages/core-components/src/layout/Sidebar/utils.ts
index 1afebe796d..7c85110aca 100644
--- a/packages/core-components/src/layout/Sidebar/utils.ts
+++ b/packages/core-components/src/layout/Sidebar/utils.ts
@@ -33,3 +33,5 @@ export function isLocationMatch(currentLocation: Location, toLocation: Path) {
 
   return matching;
 }
+
+export const isExternalLink = (link: string) => /^http/.test(link);