test(toolkit): Add region provider remote test (#6425)

## Problem
In the release yesterday we found an issue where fetching remote region
data was failing

## Solution
Add a new test since its critical to the flow


---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: jpinkney-aws

packages/core/src/shared/regions/regionProvider.ts

@@ -162,25 +162,30 @@ export class RegionProvider {
         remote: () => Endpoints | Promise<Endpoints>
     }): RegionProvider {
         const instance = new this()
+        void instance.init(endpointsProvider)
+        return instance
+    }
 
-        async function load() {
-            getLogger().info('endpoints: retrieving AWS endpoints data')
-            instance.loadFromEndpoints(await endpointsProvider.local())
-
-            try {
-                instance.loadFromEndpoints(await endpointsProvider.remote())
-            } catch (err) {
-                getLogger().warn(
-                    `endpoints: failed to load from remote source, region data may appear outdated: %s`,
-                    err
-                )
-            }
+    async init(endpointsProvider: {
+        local: () => Endpoints | Promise<Endpoints>
+        remote: () => Endpoints | Promise<Endpoints>
+    }) {
+        getLogger().info('endpoints: retrieving AWS endpoints data')
+
+        try {
+            this.loadFromEndpoints(await endpointsProvider.local())
+        } catch (err) {
+            getLogger().warn(`endpoints: failed to load from local source: %s`, err)
         }
 
-        load().catch((err) => {
-            getLogger().error('Failure while loading Endpoints Manifest: %s', err)
+        try {
+            this.loadFromEndpoints(await endpointsProvider.remote())
+        } catch (err) {
+            getLogger().warn(`endpoints: failed to load from remote source, region data may appear outdated: %s`, err)
+        }
 
-            return vscode.window.showErrorMessage(
+        if (this.getRegions().length === 0) {
+            void vscode.window.showErrorMessage(
                 `${localize(
                     'AWS.error.endpoint.load.failure',
                     'The {0} Toolkit was unable to load endpoints data.',
@@ -190,9 +195,7 @@ export class RegionProvider {
                     'Toolkit functionality may be impacted until VS Code is restarted.'
                 )}`
             )
-        })
-
-        return instance
+        }
     }
 }
 

packages/core/src/testInteg/regionProvider.test.ts

@@ -0,0 +1,37 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import assert from 'assert'
+import { makeEndpointsProvider } from '../extension'
+import { RegionProvider } from '../shared/regions/regionProvider'
+import globals from '../shared/extensionGlobals'
+import path from 'path'
+import { TestFolder } from '../test/testUtil'
+
+describe('Region Provider', async function () {
+    let tempFolder: TestFolder
+
+    before(async () => {
+        tempFolder = await TestFolder.create()
+    })
+
+    it('resolves from remote', async function () {
+        /**
+         * Make sure the local file doesn't resolve to any endpoints.
+         * That way we can make sure remote contents are fetched
+         */
+        await tempFolder.write('foo.json', '{}')
+        globals.manifestPaths.endpoints = path.join(tempFolder.path, 'foo.json')
+
+        await assert.doesNotReject(async () => {
+            const endpointProvider = makeEndpointsProvider()
+            const regionProvider = new RegionProvider()
+            await regionProvider.init(endpointProvider)
+
+            // regions loaded from the remote
+            assert.ok(regionProvider.getRegions().length > 0)
+        })
+    })
+})