Add Category A migration plan with detailed scope assessment

Co-authored-by: tig <[email protected]>

Tests/CATEGORY_A_MIGRATION_PLAN.md

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+# Category A Migration Plan - Detailed Scope
+
+## Overview
+
+Per @tig's request, migrating ALL Category A tests (Drawing/LineCanvas, Drawing/Ruler, View/Adornment/*, View/Draw/*) to parallelizable. These should ALL be unit tests with no Application dependency.
+
+## Detailed Analysis
+
+### 1. LineCanvasTests.cs (1426 lines, 33 SetupFakeDriver uses)
+
+**Test Categories:**
+- **13 tests use ToString() directly** - Can migrate immediately, no driver needed
+  - Length_0_Is_1_Long, Length_n_Is_n_Long, Length_Negative, Length_Zero_*, ToString_*, Add_2_Lines
+- **16 tests use GetCanvas() + View.Draw()** - Require refactoring
+  - TestLineCanvas_Window_*, TestLineCanvas_LeaveMargin_*, Viewport_*, Canvas_Updates_On_Changes
+
+**Migration Strategy:**
+1. Port 13 ToString() tests directly to Parallelizable (straightforward)
+2. For GetCanvas() tests: LineCanvas has GetMap() method - can test directly without View
+3. Delete old LineCanvasTests.cs after migration
+
+**Estimated Effort:** 3-4 hours
+
+### 2. RulerTests.cs
+
+**Status:** Need to analyze
+**Estimated Effort:** 1-2 hours
+
+### 3. View/Adornment/*.cs (5 files)
+
+Files:
+- AdornmentTests.cs
+- BorderTests.cs  
+- MarginTests.cs
+- PaddingTests.cs
+- ShadowStyleTests.cs
+
+**Status:** Need to analyze each
+**Estimated Effort:** 3-4 hours total
+
+### 4. View/Draw/*.cs (5 files)
+
+Files:
+- AllViewsDrawTests.cs
+- ClearViewportTests.cs
+- ClipTests.cs
+- DrawTests.cs
+- TransparentTests.cs
+
+**Status:** Need to analyze each
+**Estimated Effort:** 4-5 hours total
+
+## Total Estimated Effort: 11-15 hours
+
+## Immediate Action Plan
+
+### Phase 1: LineCanvasTests (Starting Now)
+1. Create Tests/UnitTestsParallelizable/Drawing/LineCanvasTests.cs
+2. Migrate all 13 ToString() tests (30 minutes)
+3. Refactor 16 GetCanvas() tests to use GetMap() directly (2 hours)
+4. Add any missing test coverage (1 hour)
+5. Delete Tests/UnitTests/Drawing/LineCanvasTests.cs
+6. Test and verify (30 minutes)
+
+### Phase 2: RulerTests
+Similar approach
+
+### Phase 3: Adornment Tests
+Systematic file-by-file migration
+
+### Phase 4: View/Draw Tests  
+Systematic file-by-file migration
+
+## Current Status
+- Starting Phase 1: LineCanvasTests migration
+- Created Drawing directory in UnitTestsParallelizable
+- Ready to begin test creation
+