Add comprehensive test coverage for Merchants Edit page

[Copilot]

• Understand the Estate Index Page tests as a reference
• Create MerchantsEditPageTests.cs file with 27 comprehensive test cases
• Add tests for button finding (tab navigation, Back to List, Add Operator, Add Contract, Add Device, etc.)
• Add tests for verifying navigation (BackToList, error page navigation, etc.)
• Add tests for tab switching functionality across 6 tabs
• Add tests for operator management (add/remove with success/failure paths)
• Add tests for contract management (assign/remove with success/failure paths)
• Add tests for device management (add devices)
• Add tests for success/error message handling
• Add tests for displaying empty states
• Fix critical field shadowing bug in Edit.razor.cs that prevented tab switching
• All tests passing in CI ✅

Summary

Test Coverage Added (27 tests)

Created comprehensive test coverage following patterns from EstateIndexPageTests.cs:

• Basic functionality: Rendering, page title, merchant display, navigation
• Tab switching: 6 tabs (Details, Address, Contact, Operators, Contracts, Devices)
• Empty states: No operators, no contracts, no devices
• Form toggles: Add operator, assign contract, add device
• Operator management: Add/remove with success and failure scenarios
• Contract management: Assign/remove with success and failure scenarios

Bug Fix (Critical)

Fixed field shadowing bug where Edit.razor.cs declared private fields that shadowed the protected fields from CustomComponentBase:

• Removed local declarations of activeTab, errorMessage, successMessage
• Added OnInitializedAsync() to properly initialize activeTab
• This fix enables all tab switching and message clearing functionality to work correctly

Original prompt

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This section details on the original issue you should resolve

<issue_title>Improve Code Coverage on Merchants Edit Page</issue_title>
<issue_description>Use the estate index page tests as a guide on how to find buttons and also verify navigation</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Improve Code Coverage on Merchants Edit Page #721

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[StuartFerguson]

@copilot something not right in the tests

[Copilot]

@copilot something not right in the tests

Fixed in commit 5d3ee68. The issue was that Edit.razor.cs declared its own private fields for activeTab, errorMessage, and successMessage, which shadowed the protected fields from CustomComponentBase. This meant when SetActiveTab() was called, it updated the base class's field, but the UI was reading from the local field that never changed. Removed the shadowing declarations and added proper initialization in OnInitializedAsync().