Magento should create a log entry if an observer does not implement ObserverInterface

[bnymn]

Summary (*)

In developer mode, if an observer does not implement ObserverInterface, Magento throws an exception. This is the expected behavior.

What I don't understand is that it does not do anything for other deploy modes (default and production). It silently discards the observer without even putting an entry to logs.

Examples (*)

This is the method where problem occurs. There is only one condition for developer mode, but other deploy modes are ignored.

    /**
     * @param \Magento\Framework\Event\ObserverInterface $object
     * @param Observer $observer
     * @return $this
     * @throws \LogicException
     */
    protected function _callObserverMethod($object, $observer)
    {
        if ($object instanceof \Magento\Framework\Event\ObserverInterface) {
            $object->execute($observer);
        } elseif ($this->_appState->getMode() == \Magento\Framework\App\State::MODE_DEVELOPER) {
            throw new \LogicException(
                sprintf(
                    'Observer "%s" must implement interface "%s"',
                    get_class($object),
                    \Magento\Framework\Event\ObserverInterface::class
                )
            );
        }
        return $this;
    }

Proposed solution

We can put an else condition. Then, we can log the same exception message in warning level.

[magento-engcom-team]

Hi @bnymn. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

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Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

@magento-engcom-team give me 2.3-develop instance - upcoming 2.3.x release

For more details, please, review the Magento Contributor Assistant documentation.

@bnymn do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

[magento-engcom-team]

Hi @engcom-backlog-nazar. Thank you for working on this issue.
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[magento-engcom-team]

✅ Confirmed by @engcom-backlog-nazar
Thank you for verifying the issue. Based on the provided information internal tickets MAGETWO-98704 were created

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[magento-engcom-team]

Hi @Nazar65. Thank you for working on this issue.
Looks like this issue is already verified and confirmed. But if you want to validate it one more time, please, go though the following instruction:

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[magento-engcom-team]

Hi @bnymn. Thank you for your report.
The issue has been fixed in #21767 by @Nazar65 in 2.3-develop branch
Related commit(s):

• c3e4f07b3d377dce75c3968d2d9ced1c3d31538f
• 2e0a846b0b0d3bdcac0786ed7e91eaf96c0d501e
• 0d75cd04d973fc64c8a47ea14f20fa5a861061d5
• a6ef1186bf5003b6e9868eb96ab36d079407b3a9

The fix will be available with the upcoming 2.3.2 release.

[magento-engcom-team]

Hi @bnymn. Thank you for your report.
The issue has been fixed in #22232 by @Nazar65 in 2.2-develop branch
Related commit(s):

• 4223d2b6e0b2f119d6e34c618a0dc78fbbecdcd1

The fix will be available with the upcoming 2.2.9 release.