---
phase: 09-storage-visualization
plan: 04
subsystem: storage-visualization
tags: [tests, unit-tests, charts, viewmodel, xunit]
dependency_graph:
  requires: [09-03]
  provides: [chart-unit-tests]
  affects: [SharepointToolbox.Tests]
tech_stack:
  added: []
  patterns: [reflection-based-property-setting, moq-service-mocking]
key_files:
  created:
    - SharepointToolbox.Tests/ViewModels/StorageViewModelChartTests.cs
  modified:
    - SharepointToolbox.Tests/SharepointToolbox.Tests.csproj
decisions:
  - "Used reflection to set FileTypeMetrics (private setter) instead of mocking full RunOperationAsync flow -- avoids sealed ClientContext dependency"
  - "Added LiveChartsCore.SkiaSharpView.WPF 2.0.0-rc5.4 to test project to match main project version"
  - "Asserted against DisplayLabel-uppercased 'OTHER' not raw 'Other' to match FileTypeMetric.DisplayLabel behavior"
metrics:
  duration: 146s
  completed: "2026-04-07"
---

# Phase 09 Plan 04: StorageViewModel Chart Unit Tests Summary

7 xUnit tests verifying chart series computation from FileTypeMetrics, donut/bar toggle via InnerRadius, top-10+Other aggregation, tenant switch cleanup, and empty data edge case -- all without SharePoint connection.

## What Was Done

### Task 1: Create StorageViewModel chart unit tests (TDD)

Created `StorageViewModelChartTests.cs` with 7 tests:

1. **After_setting_metrics_HasChartData_is_true_and_PieChartSeries_has_entries** -- Sets 5 metrics, asserts HasChartData=true and PieChartSeries count=5
2. **After_setting_metrics_BarChartSeries_has_one_ColumnSeries_with_matching_values** -- Verifies single ColumnSeries with value count matching metric count
3. **Toggle_IsDonutChart_changes_PieChartSeries_InnerRadius** -- Asserts InnerRadius=50 when donut, 0 when toggled off
4. **More_than_10_metrics_produces_11_series_entries_with_Other** -- 15 metrics produce 10+1 "OTHER" entries in pie, bar, and x-axis labels
5. **Ten_or_fewer_metrics_produces_no_Other_entry** -- 10 metrics produce exactly 10 entries, no "OTHER"
6. **OnTenantSwitched_clears_FileTypeMetrics_and_HasChartData_is_false** -- TenantSwitchedMessage clears all chart state
7. **Empty_metrics_yields_HasChartData_false_and_empty_series** -- Empty input produces empty series and false HasChartData

**Approach:** Uses reflection to set `FileTypeMetrics` property (private setter triggers `UpdateChartSeries` internally), bypassing the need to mock sealed `ClientContext` for `RunOperationAsync`.

**NuGet:** Added `LiveChartsCore.SkiaSharpView.WPF 2.0.0-rc5.4` to test project (matching main project version) for `PieSeries<T>`, `ColumnSeries<T>` type assertions.

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] "Other" series name uses DisplayLabel not raw extension**
- **Found during:** TDD RED phase
- **Issue:** Test asserted `Name == "Other"` but FileTypeMetric("Other", ...).DisplayLabel returns "OTHER" (ToUpperInvariant)
- **Fix:** Changed assertions to expect "OTHER"
- **Files modified:** StorageViewModelChartTests.cs
- **Commit:** 712b949

## Verification

- All 7 chart tests pass
- Full suite: 210 passed, 22 skipped, 0 failed -- no regressions

## Commits

| Hash | Message |
|------|---------|
| 712b949 | test(09-04): add StorageViewModel chart unit tests |

## Self-Check: PASSED