Guard against precision issues on time fractions

Author: lcobucci

test/functional/HmacTokenTest.php

@@ -3,6 +3,7 @@
 
 namespace Lcobucci\JWT\FunctionalTests;
 
+use DateTimeImmutable;
 use Lcobucci\JWT\Configuration;
 use Lcobucci\JWT\Signer\Hmac\Sha256;
 use Lcobucci\JWT\Signer\Hmac\Sha512;
@@ -131,4 +132,36 @@ public function everythingShouldWorkWhenUsingATokenGeneratedByOtherLibs(): void
         self::assertTrue($this->config->validator()->validate($token, $constraint));
         self::assertEquals('world', $token->claims()->get('hello'));
     }
+
+    /**
+     * @test
+     * @dataProvider datesWithPotentialRoundingIssues
+     */
+    public function timeFractionsPrecisionsAreRespected(DateTimeImmutable $issuedAt): void
+    {
+        $token = $this->config->builder()
+            ->issuedAt($issuedAt)
+            ->getToken($this->config->signer(), $this->config->signingKey());
+
+        $parsedToken = $this->config->parser()->parse($token->toString());
+
+        self::assertInstanceOf(Token\Plain::class, $parsedToken);
+        self::assertSame($issuedAt->format('U.u'), $parsedToken->claims()->get('iat')->format('U.u'));
+    }
+
+    /** @return iterable<DateTimeImmutable[]> */
+    public function datesWithPotentialRoundingIssues(): iterable
+    {
+        $create = static function (string $timeFraction): DateTimeImmutable {
+            $date = DateTimeImmutable::createFromFormat('U.u', $timeFraction);
+            assert($date instanceof DateTimeImmutable);
+
+            return $date;
+        };
+
+        yield [$create('1613938511.017448')];
+        yield [$create('1613938511.023691')];
+        yield [$create('1613938511.018045')];
+        yield [$create('1616074725.008455')];
+    }
 }