Fix #5336: General system alert visible to users in real time without…

[guillermo-escire]

References

• Fixes System-Wide Alert: Not visible to users in real time without page reload #5336

Description

Fixes an issue where system-wide alerts were not updated in real time for users already browsing the site. The alert banner now refreshes on navigation and properly handles deactivation without requiring a manual page reload.

Instructions for Reviewers

This PR ensures that system-wide alerts are dynamically updated during normal navigation without requiring a full page reload.

Changes

List of changes in this PR:

• Re-fetch system-wide alerts on every NavigationEnd router event
• Added startWith(null) to trigger initial fetch on component load
• Disabled cache usage in searchBy to ensure fresh data is retrieved
• Updated logic to handle empty responses (no active alerts) by emitting null
• Ensured banner is hidden when no active alert exists
• Added Router mock in unit tests to support new reactive flow

How to test

1. Open DSpace in two browser sessions (or one normal + one incognito)

2. In Browser 1:

   • Navigate to any page (e.g. homepage)

3. In Browser 2 (admin user):

   • Go to System-Wide Alert settings
   • Enable a new alert and save

4. In Browser 1:

   • Navigate to another page (without refreshing)
   • ✅ The alert should now appear

5. Still in Browser 2:

   • Disable the alert and save

6. In Browser 1:

   • Navigate again
   • ✅ The alert should disappear

Checklist

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