Feature: quickfiler-collection-controller-coverage #454

• Work Mode: full-feature

Problem / Why

QuickFiler/Controllers/QfcCollectionController.cs is the single largest production file in the
repository at 2,349 lines. It carries a real [ExcludeFromCodeCoverage] attribute, so it is absent
from every Cobertura report the repository produces: it is unmeasured, not covered. Its
interface, QuickFiler/Interfaces/IQfcCollectionController.cs (118 lines), completes the pair.

Three repository policies are violated or unenforced against this file today:

1. .claude/rules/general-code-change.md sets a 500-line ceiling for production files. At 2,349
   lines the file breaches it by a factor of nearly five.
2. .claude/rules/general-unit-test.md § Coverage Exclusion Policy states that no production file
   may be excluded from coverage measurement, and that the correct response to untestable lines is
   refactoring, not exclusion.
3. Issue Feature: quickfiler-80-per-file-coverage #136 AC1 requires every compiled QuickFiler file to reach >= 80% line coverage or sit on a
   ratified exemption ledger with a file-specific rationale.

The epic manifest (docs/features/epics/quickfiler-per-file-coverage/epic.md) makes this file its
own child precisely because closing the gap requires three substantial pieces of work in strict
sequence: a partial split into at least five files to satisfy the 500-line rule, seam extraction so
the logic is reachable without live COM or WinForms, and only then the coverage itself.

Proposed Behavior

No observable behavior change to QuickFiler flows. The work is a testability refactor plus test
authorship:

1. Split QfcCollectionController.cs into coherent partial-class files along logical responsibility
   seams (not mechanical 500-line chops), each under 500 lines.
2. Extract seams - interface seam first, injectable delegate second, adapter third - so the
   controller's logic is reachable from MSTest without constructing live forms, showing popups,
   touching the UI thread, or instantiating Outlook COM objects.
3. Remove [ExcludeFromCodeCoverage] and author MSTest/Moq/FluentAssertions tests bringing each
   resulting partial to >= 80% line and >= 75% branch coverage, with newly created files reaching

   = 90% line coverage per the CLAUDE.md new-module rule.

Acceptance Criteria

• QfcCollectionController and every partial it is split into reaches >= 80% line and >= 75%
  branch coverage, verified with F1's per-file harness and recorded under
  <FEATURE>/evidence/qa-gates/.
• [ExcludeFromCodeCoverage] is removed from QfcCollectionController.cs and the code is
  genuinely covered. A blanket re-exemption of the whole file is not acceptable; an irreducible
  remainder is acceptable only where F1's ledger ratifies it with a file-specific rationale.
• No production file in scope exceeds 500 lines.
• Every file newly created by this work reaches >= 90% line coverage.
• Tests use MSTest, Moq, and FluentAssertions; are deterministic and isolated; create no
  temporary files; contact no external services; construct no live forms; raise no popups.
• The full C# toolchain (csharpier, analyzers, nullable, MSTest with coverage) is green in the
  final form, and repository-wide coverage is retained or improved.
• No behavior change to observable QuickFiler flows.

Constraints & Risks

• QuickFiler.csproj edits are guaranteed. The project is a legacy non-SDK project with no
  globbing; every new partial needs an explicit <Compile Include=...> entry. Per epic.md
  "Cross-Child Constraints" section 1: only this child's own entries, minimal adjacent hunks, and
  CRLF must be preserved. An additive fan-in conflict with siblings is anticipated, not a defect.
• Upstream dependency on F1 (quickfiler-coverage-ledger, wave 0) for the per-file coverage
  harness and the ledger at docs/features/epics/quickfiler-per-file-coverage/coverage-ledger.md.
  A ledger row must be appended for every new file per epic.md "Mid-Wave File Creation".
• Sibling boundaries. This controller is consumed by QfcHomeController (F7, Feature: quickfiler-qfc-home-controller-coverage #433) and consumes
  IQfcDatamodel (F5) and IQfcQueue (F2, Feature: quickfiler-queue-admission-coverage #431). No sibling files may be edited. Seams should stay
  internal to the class where possible so F7's conclusion that it needs no contract additions
  remains true.
• No InternalsVisibleTo grant from UtilitiesCS to QuickFiler.Test. A local seam must be
  built rather than editing UtilitiesCS/Properties/AssemblyInfo.cs.
• Known defect out of scope. Issue Bug: kbdactions-enumerable-ctor-bypasses-duplicate-guard #444 records that QfcCollectionController.cs:1265-1272
  registers two KaKey entries sharing SourceId="Collection" and Keys.Down, so
  Find(Keys.Down) throws. Under the epic's no-behavior-change NFR this is characterized, not
  fixed, and referenced by number.
• Starting coverage is unknown and likely near zero. The exemption removes the file from
  instrumentation entirely, so no historical number exists. Two test files
  (QfcCollectionControllerTests.cs, QfcCollectionControllerDarkModeTests.cs) already exist; what
  they actually reach given the exemption must be established during research.

Test Conditions

• Per-partial unit coverage for every responsibility group produced by the split.
• Seam-level tests exercising injected delegates and adapters without live COM or forms.
• Characterization of the Bug: kbdactions-enumerable-ctor-bypasses-duplicate-guard #444 duplicate-KaKey registration without changing behavior.
• STA last-resort tests, if unavoidable, isolated in dedicated *.StaTests.cs files.
• Branch-coverage-sensitive scenarios (the 75% branch gate is independent of the 80% line gate).

Source

From: docs/features/potential/2026-08-07-quickfiler-collection-controller-coverage.md