Fixes callback typing in credentials refresh (#3172)

* Fix for no error object in typings if refresh succeeds for credentials

Fixes [#3140](#3140)

* Adds changelog for fix for #3140

Co-authored-by: Anmol Dalmia <anmold@amazon.com>

.changes/next-release/bugfix-Typings-2e38bbb7.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "Typings",
+  "description": "When implementing `Credentials` interface's `refresh()` method, the callback needs a defined `AWSError` as arg but it may not exist in case of successful refresh. Hence, modifed the method typing to include the fact that the callback can be called with no error on success as described in the docs."
+}

lib/credentials/cognito_identity_credentials.d.ts

@@ -16,7 +16,7 @@ export class CognitoIdentityCredentials extends Credentials {
     /**
      * Refreshes credentials using AWS.CognitoIdentity.getCredentialsForIdentity(), or AWS.STS.assumeRoleWithWebIdentity().
      */
-    refresh(callback: (err: AWSError) => void): void;
+    refresh(callback: (err?: AWSError) => void): void;
     /**
      * Clears the cached Cognito ID associated with the currently configured identity pool ID.
      */
@@ -40,4 +40,4 @@ declare namespace CognitoIdentityCredentials {
     export type CognitoIdentityCredentialsInputs = CognitoIdentity.GetIdInput|CognitoIdentity.GetCredentialsForIdentityInput|CognitoIdentity.GetOpenIdTokenInput|STS.AssumeRoleWithWebIdentityRequest;
     export type CognitoIdentityOptions = CognitoIdentityCredentialsInputs & {LoginId?: string};
     export type ClientConfiguration = ConfigurationOptions;
-}
+}

lib/credentials/temporary_credentials.d.ts

@@ -17,7 +17,7 @@ export class TemporaryCredentials extends Credentials {
     /**
      * Refreshes credentials using AWS.STS.assumeRole() or AWS.STS.getSessionToken(), depending on whether an IAM role ARN was passed to the credentials constructor().
      */
-    refresh(callback: (err: AWSError) => void): void;
+    refresh(callback: (err?: AWSError) => void): void;
 
     /**
      * The master (non-temporary) credentials used to get and refresh temporary credentials from AWS STS.
@@ -28,4 +28,4 @@ export class TemporaryCredentials extends Credentials {
 // Needed to expose interfaces on the class
 declare namespace TemporaryCredentials {
     export type TemporaryCredentialsOptions = STS.Types.AssumeRoleRequest|STS.Types.GetSessionTokenRequest;
-}
+}

lib/credentials/token_file_web_identity_credentials.d.ts

@@ -10,5 +10,5 @@ export class TokenFileWebIdentityCredentials extends Credentials {
     /**
      * Refreshes credentials using AWS.STS.assumeRoleWithWebIdentity().
      */
-    refresh(callback: (err: AWSError) => void): void;
-}
+    refresh(callback: (err?: AWSError) => void): void;
+}

lib/credentials/web_identity_credentials.d.ts

@@ -17,7 +17,7 @@ export class WebIdentityCredentials extends Credentials {
     /**
      * Refreshes credentials using AWS.STS.assumeRoleWithWebIdentity().
      */
-    refresh(callback: (err: AWSError) => void): void;
+    refresh(callback: (err?: AWSError) => void): void;
 
     data: STS.Types.AssumeRoleWithWebIdentityResponse;
     params: STS.Types.AssumeRoleWithWebIdentityRequest
@@ -27,4 +27,4 @@ export class WebIdentityCredentials extends Credentials {
 declare namespace WebIdentityCredentials {
     export type ClientConfiguration = ConfigurationOptions;
     export type WebIdentityCredentialsOptions = STS.AssumeRoleWithWebIdentityRequest;
-}
+}

package.json

@@ -146,4 +146,4 @@
     "helper-test": "mocha scripts/lib/test-helper.spec.js",
     "csm-functional-test": "mocha test/publisher/functional_test"
   }
-}
+}

ts/credentials.ts

@@ -15,7 +15,7 @@ creds.getPromise().then(
 );
 
 if (creds.needsRefresh()) {
-    creds.refresh(err => {
+    creds.refresh((err = undefined) => {
 
     });