bulk-file-renamer

Windows desktop app for batch-renaming files. Pipeline of composable rules with a live preview, conflict detection, and undo. WPF + MVVM front-end on top of a pure rule-engine library that's covered by xUnit.

Application window screenshot lands here once captured.

Features

• Add files via dialog (Add files...), an entire folder (Add folder...), or drag-and-drop straight onto the preview grid.
• Six composable rules, applied in a fixed, easy-to-reason order:
  1. Search and replace (case sensitive by default)
  2. Remove characters from a deny-list
  3. Change case (lower / UPPER / Title)
  4. Prefix
  5. Suffix
  6. Sequential numbering (configurable start / step / padding / position / separator)
• Live preview — every edit recomputes new names instantly through CommunityToolkit.Mvvm's generated OnXxxChanged hooks.
• Conflict detection — rows whose target paths collide are highlighted in red; the Apply button stays disabled until conflicts are resolved.
• Undo the last batch. Renames are replayed in opposite order so chained moves restore cleanly.

Architecture

Three projects in one solution, all targeting net8.0:

src/BulkFileRenamer.Core      Pure logic — rules, pipeline, planner,
                              ConflictDetector, RenameExecutor.
                              No WPF, no Windows-specific types.
src/BulkFileRenamer.App       WPF UI. Single MainWindow + MainViewModel,
                              uses CommunityToolkit.Mvvm.
tests/BulkFileRenamer.Tests   xUnit suite over Core (28 tests).

Splitting Core out is the load-bearing design choice: the rules and planner can be tested in isolation without spinning up a window, and the ViewModel composes them as a stack of IRenameRule instances. The UI is thin glue.

Building

Requires .NET 8 SDK and Windows (WPF target framework is net8.0-windows).

dotnet restore
dotnet build --configuration Release
dotnet test  --configuration Release --no-build

Run the app:

dotnet run --project src/BulkFileRenamer.App

Tests

dotnet test runs 28 xUnit cases covering:

• Each rule — empty-input noop, case sensitivity, padding / step / position variants, mode table for case change, character-set semantics
• Pipeline — order, identity, full path composition
• Planner — order, noop detection
• Conflict detector — unique destinations, pairwise / 3-way collisions, case-insensitive path comparison
• Executor — mover invocation, noop skipping, Undo order
• Integration — real filesystem round-trip in a temp directory

CI runs the same on windows-latest for every push and pull request — see .github/workflows/ci.yml.

Out of scope

By design: no regex rules (text find/replace only), no cloud features, no undo history beyond the last operation, no support for other operating systems (WPF is Windows-only). The Core library itself is OS-agnostic and could power a console or cross-platform UI separately.

License

MIT.