refactor to spy on debounced funcitionality

We can now spy on the underlying getToken method to verify
it is being debounced as expected.

Also reduce the debounce interval to 50ms to reduce the delay but still
catch a barrage of calls

Signed-off-by: nkomonen-amazon <[email protected]>

Author: nkomonen-amazon

packages/core/src/auth/sso/ssoAccessTokenProvider.ts

@@ -108,8 +108,9 @@ export abstract class SsoAccessTokenProvider {
     public async getToken(): Promise<SsoToken | undefined> {
         return this.getTokenDebounced()
     }
-    private getTokenDebounced = debounce(this._getToken.bind(this), 100)
-    private async _getToken(): Promise<SsoToken | undefined> {
+    private getTokenDebounced = debounce(() => this._getToken(), 50)
+    /** Exposed for testing purposes only */
+    public async _getToken(): Promise<SsoToken | undefined> {
         const data = await this.cache.token.load(this.tokenCacheKey)
         SsoAccessTokenProvider.logIfChanged(
             indent(

packages/core/src/test/credentials/sso/ssoAccessTokenProvider.test.ts

@@ -156,13 +156,15 @@ describe('SsoAccessTokenProvider', function () {
             assert.strictEqual(cachedToken, undefined)
         })
 
-        it('concurrent calls resolve successfully', async function () {
-            // This test verifies debounced getToken() does not break things.
-            // But this test is not perfect since we are unable to spy _getToken() for some reason.
+        it('concurrent calls are debounced', async function () {
             const validToken = createToken(hourInMs)
             await cache.token.save(startUrl, { region, startUrl, token: validToken })
+            const actualGetToken = sinon.spy(sut, '_getToken')
 
             const result = await Promise.all([sut.getToken(), sut.getToken(), sut.getToken()])
+
+            // Subsequent other calls were debounced so this was only called once
+            assert.strictEqual(actualGetToken.callCount, 1)
             for (const r of result) {
                 assert.deepStrictEqual(r, validToken)
             }