<?php

namespace Unit;

use Codeception\Attribute\DataProvider;
use Codeception\Example;
use PHPUnit\Framework\Assert as Assert;

enum ExampleEnum
{
    case FOO;
    case BAR;
}

class ExampleCest
{
    protected function EnumProvider(): array
    {
        return [
            ['expected' => ExampleEnum::FOO, 'result' => ExampleEnum::BAR],
            ['expected' => ExampleEnum::BAR, 'result' => ExampleEnum::BAR],
        ];
    }

    #[DataProvider('EnumProvider')]
    public function testEnum(Example $example)
    {
        Assert::assertSame($example['expected'], $example['result']);
    }
}

There was 1 error:
1) ExampleCest: Test enum | "Unit\\ExampleEnum","Unit\\ExampleEnum"
 Test  tests/unit/ExampleCest.php:testEnum
                                                                  
  [JsonException] Non-backed enums have no default serialization