fix(NODE-6801): set token on connection from cache (#4438)

Author: durran

src/cmap/auth/mongodb_oidc/machine_workflow.ts

@@ -94,7 +94,12 @@ export abstract class MachineWorkflow implements Workflow {
     credentials: MongoCredentials
   ): Promise<string> {
     if (this.cache.hasAccessToken) {
-      return this.cache.getAccessToken();
+      const token = this.cache.getAccessToken();
+      // New connections won't have an access token so ensure we set here.
+      if (!connection.accessToken) {
+        connection.accessToken = token;
+      }
+      return token;
     } else {
       const token = await this.callback(credentials);
       this.cache.put({ accessToken: token.access_token, expiresInSeconds: token.expires_in });

test/unit/cmap/auth/mongodb_oidc/gcp_machine_workflow.test.ts

@@ -19,4 +19,28 @@ describe('GCPMachineFlow', function () {
       });
     });
   });
+
+  describe('#getTokenFromCacheOrEnv', function () {
+    context('when the cache has a token', function () {
+      const connection = sinon.createStubInstance(Connection);
+      const credentials = sinon.createStubInstance(MongoCredentials);
+
+      context('when the connection has no token', function () {
+        let cache;
+        let workflow;
+
+        this.beforeEach(function () {
+          cache = new TokenCache();
+          cache.put({ accessToken: 'test', expiresInSeconds: 7200 });
+          workflow = new GCPMachineWorkflow(cache);
+        });
+
+        it('sets the token on the connection', async function () {
+          const token = await workflow.getTokenFromCacheOrEnv(connection, credentials);
+          expect(token).to.equal('test');
+          expect(connection.accessToken).to.equal('test');
+        });
+      });
+    });
+  });
 });