Restore pre 5.1.1 behavior and fix types

[frederikprijck]

Changes

Release v5.1.1 changed the code in such a way that calling decodeToken('') would call the tokenGetter, while previously it would return null.

Same for isTokenExpired(''), which used to return false, while in 5.1.1 it invokes the tokenGetter. And getTokenExpirationDate, which used to return null, is also calling the tokenGetter in 5.1.1.

The PR reverts that behavior to restore it to the behavior it had pre-5.1.1.

On top of that, this PR is also fixing the types to ensure the following types are correct:

interface Foo { }

var svc = new JwtHelperService();

var token1: null | Foo | Promise<Foo | null> = svc.decodeToken<Foo>();
var token2: null | Foo = svc.decodeToken<Foo>('gdfgdf');
var token2: null | Foo = svc.decodeToken<Foo>('');
var token3: Promise<Foo | null> = svc.decodeToken<Foo>(Promise.resolve(''));

var exp1: Boolean | Promise<Boolean> = svc.isTokenExpired();
var exp2: Boolean = svc.isTokenExpired('');
var exp3: Promise<Boolean> = svc.isTokenExpired(Promise.resolve(''));
var exp4: Boolean = svc.isTokenExpired(null, 10);
var exp4: Boolean | Promise<Boolean> = svc.isTokenExpired(undefined, 10);

var expD1: null | Date | Promise<null | Date> = svc.getTokenExpirationDate();
var expD2: null | Date = svc.getTokenExpirationDate('');
var expD3: Promise<null | Date> = svc.getTokenExpirationDate(Promise.resolve(''));

Added tests to ensure the above using tsd.

I have also added additional tests to cover for the behavior that got broken in 5.1.1.

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All code quality tools/guidelines in the CONTRIBUTING documentation have been run/followed
• All relevant assets have been compiled as directed in the CONTRIBUTING documentation, if applicable

[codecov]

Codecov Report

Base: 85.71% // Head: 85.71% // No change to project coverage 👍

Coverage data is based on head (bff7678) compared to base (29045be).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #759   +/-   ##
=======================================
  Coverage   85.71%   85.71%           
=======================================
  Files           2        2           
  Lines           7        7           
=======================================
  Hits            6        6           
  Misses          1        1           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.