Add create-solution-filters command for converting multiple solutions

[psmulovics]

Overview

Implements Issue #49 to add a new command that converts multiple .sln files in a multi-solution repository into a single consolidated solution with individual .slnf (solution filter) files for each original solution.

This enables teams to migrate from a multi-solution structure to a monorepo while maintaining separate filtering options for different solution contexts.

Command Syntax

please create-solution-filters --from <glob-pattern> --target <target-solution>

Behavior

The command performs the following steps:

1. Discovery: Finds all .sln files matching the glob pattern
2. Consolidation:
   • Creates or uses existing target solution
   • Extracts projects from each source solution
   • Adds them to the target under solution folders (named after source solutions)
3. Filter Generation: Creates .slnf JSON files for each original solution that filter the target solution to show only its original projects
4. Cleanup: Deletes source .sln files after successful conversion

Example

Before:

Solution1.sln (contains ProjectA, ProjectB)
Solution2.sln (contains ProjectC, ProjectD)

After running: please create-solution-filters --from "Solution*.sln" --target "Consolidated.sln"

Result:

Consolidated.sln (contains all projects organized by solution folder)
├── Solution1/
│   ├── ProjectA
│   └── ProjectB
├── Solution2/
│   ├── ProjectC
│   └── ProjectD

Solution1.slnf (filters to Solution1's projects)
Solution2.slnf (filters to Solution2's projects)

Solution1.sln (deleted)
Solution2.sln (deleted)

Implementation Details

• Architecture: Follows existing dotnet-please patterns (attribute-based command discovery, Mediator pattern)
• Glob Support: Reuses existing MSBuildHelper.GetProjectInfosFromGlob() for flexible pattern matching
• CLI Integration: Uses DotNetCliHelper.AddProjectToSolution() for reliable project addition via dotnet sln CLI
• Solution Filters: Generates valid JSON .slnf files with proper camelCase property names
• Dry-Run Support: Full integration with existing --dry-run flag
• Error Handling: Validates inputs (no matching solutions, invalid paths) and reports errors gracefully

Testing

Added comprehensive unit tests covering:

• Two-solution consolidation (dry-run and live modes)
• Reuse of existing target solution
• Multiple projects per solution
• Single solution handling
• All tests use [Theory, CombinatorialData] for dry-run variations

Result: ✅ All 8 tests pass

Files Changed

• DotNetPlease/Commands/CreateSolutionFilters.cs (255 lines): Command implementation
• DotNetPlease.Tests/Commands/CreateSolutionFiltersTests.cs (240 lines): Unit tests

Notes

• Command is fully integrated and discoverable via please --help
• No breaking changes to existing functionality
• Leverages only existing helpers and standard .NET libraries (System.Text.Json)

[Copilot]

Pull request overview

Adds a new please create-solution-filters command to help migrate multi-solution repositories into a single consolidated solution while generating per-solution .slnf filter files.

Changes:

• Introduces create-solution-filters command to discover source solutions, consolidate projects into a target solution, generate .slnf files, and delete original .sln files.
• Adds unit tests covering consolidation scenarios (2 solutions, existing target, multiple projects, single solution) with dry-run permutations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
DotNetPlease/Commands/CreateSolutionFilters.cs	Implements the new CLI command for consolidating solutions and producing solution filter files.
DotNetPlease.Tests/Commands/CreateSolutionFiltersTests.cs	Adds test coverage for the new command, including dry-run behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[ZKRobi]

All in all the copilot review seems to be pretty on point with this PR.