test(ios): unit tests for the three extracted iOS view models

[datlechin]

Summary

Closes the original audit backlog by adding Swift Testing coverage for the three view models extracted in PR #1164, #1165, #1166. Each VM now has tests against an in-memory DatabaseDriver and SecureStore mock, which lock in the refactor surface so future regressions surface in CI rather than at runtime.

Coverage

DataBrowserViewModelTests (8 tests):

• load without session sets loadError
• load with session populates columns, legacyRows, columnDetails, hasPrimaryKeys
• applySearch / clearSearch toggle hasActiveSearch and activeSearchText
• goToPreviousPage clamps at 0 (no underflow)
• primaryKeyValues(for:) extracts only PK columns from a row
• deleteRow returns true on success and runs DELETE SQL through the driver
• deleteRow returns false and sets operationError on driver failure
• changePageSize resets currentPage and totalRows

ConnectionFormViewModelTests (7 tests):

• init() reads default safe mode from AppPreferences
• init(editing:) hydrates name, type, host, port, username, database, SSL, safe mode from a stored connection
• Setting type updates port to the type's default (didSet)
• canSave requires database for SQLite, host for server types
• loadStoredCredentials(secureStore:) populates password and SSH password from the seeded mock store
• clearSelectedFile() resets URL and database
• createNewDatabase() builds a .db URL in Documents and primes the connection name

RowDetailViewModelTests (8 tests):

• canEdit requires session, table, primary key, and not safe-mode-blocked
• startEditing populates editedValues from the current row
• cancelEditing clears edited values
• toggleNull flips between empty string and nil
• saveChanges with no changes early-returns true and exits edit mode without firing UPDATE
• saveChanges with changes runs UPDATE with primary keys and modified columns
• saveChanges returns false and sets operationError when no primary key value is present
• loadFullValue populates the per-cell override and clears loadingCell

Mocks

• MockDatabaseDriver is @unchecked Sendable (state mutated only from @MainActor test scope), implements all DatabaseDriver protocol requirements, and exposes scriptedExecuteResults: [Result<QueryResult, Error>] for sequenced responses
• MockSecureStore is an in-memory [String: String] backing the SecureStore protocol, with seed(_:_:) for test setup and failNextStore for forcing keychain write failures

Signature change

ConnectionFormViewModel.loadStoredCredentials(secureStore:), .testConnection(appState:secureStore:), and .save(appState:secureStore:) now accept any SecureStore instead of the concrete KeychainSecureStore. KeychainSecureStore: SecureStore, so all existing call sites (ConnectionFormView) continue to work unchanged.

Required one-time Xcode setup

The test target is not in TableProMobile.xcodeproj yet. Before the tests can run:

1. Open TableProMobile.xcodeproj in Xcode
2. File → New → Target → iOS → Unit Testing Bundle
3. Product Name: TableProMobileTests, Target to Test: TableProMobile, Testing System: Swift Testing
4. Delete the stub TableProMobileTests.swift Xcode generated; the existing files in TableProMobileTests/ will be picked up via synchronized groups

Instructions are also in TableProMobile/TableProMobileTests/README.md.

Test plan

• After Xcode test target setup, ⌘U runs all 23 tests green
• Tests pass with no real network or keychain access (everything goes through the mocks)
• Run a single suite via xcodebuild ... -only-testing:TableProMobileTests/DataBrowserViewModelTests to confirm filterable