Add Facade Pattern source generator with contract-first and host-first modes#92
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JerrettDavis merged 12 commits intomainfrom Jan 24, 2026
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Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
- Contract-first tests (interface, partial class, async, cancellation tokens, dependencies) - Host-first tests (static class, exposed methods, DI, type name generation) - Diagnostic tests (PKFCD001-PKFCD006) - Integration tests (billing & shipping scenarios, deterministic ordering) - Edge cases (empty facade, FacadeIgnore, optional names, complex types, ref params, multiple namespaces) - All 24 tests passing Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
- Create ShippingFacadeExample.cs demonstrating Host-First pattern with [FacadeExpose] - Include complete subsystem services (RateCalculator, DeliveryEstimator, etc.) - Add comprehensive README.md documenting the pattern and known limitations - Document PKFCD004 issue with Contract-First approach - Example builds successfully and demonstrates: * Multiple subsystem coordination * Dependency injection via constructor * Simplified facade API * Production-ready shipping calculations Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
…t modes Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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[WIP] Add source generator for Facade pattern implementation
Add Facade Pattern source generator with contract-first and host-first modes
Jan 23, 2026
JerrettDavis
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Jan 23, 2026
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Dependency Review✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.Scanned FilesNone |
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Test Results199 tests 199 ✅ 1m 3s ⏱️ Results for commit f6f290b. ♻️ This comment has been updated with latest results. |
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🔍 PR Validation ResultsVersion: `` ✅ Validation Steps
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Pull request overview
This pull request implements a source generator for the GoF Facade pattern, providing two modes of operation: contract-first (mapping methods to interface/class members) and host-first (generating facades from static methods with [FacadeExpose] attribute). The implementation includes 869 lines of generator code, comprehensive attribute definitions, documentation, and examples.
Changes:
- Added
FacadeGenerator.cswith IIncrementalGenerator implementation supporting both contract-first and host-first modes - Added five attribute classes in
PatternKit.Generators.Abstractions/Facadenamespace for marking facade types and methods - Added comprehensive test suite with 24 unit tests in
FacadeGeneratorTests.csand 10 integration tests inFacadeSpecsTests.cs - Added two real-world examples (
BillingFacadeExample.csandShippingFacadeExample.cs) demonstrating multi-subsystem coordination - Added documentation in
docs/generators/facade.mdand example README - Added six diagnostic IDs (PKFCD001-006) to analyzer releases
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Copilot reviewed 13 out of 13 changed files in this pull request and generated 18 comments.
Show a summary per file
| File | Description |
|---|---|
| src/PatternKit.Generators/FacadeGenerator.cs | Core generator implementing both contract-first and host-first facade generation with dependency injection |
| src/PatternKit.Generators.Abstractions/Facade/*.cs | Five attribute classes for marking types and methods for facade generation |
| src/PatternKit.Generators/AnalyzerReleases.Unshipped.md | Added six diagnostic IDs for facade pattern validation |
| test/PatternKit.Generators.Tests/FacadeGeneratorTests.cs | 24 unit tests covering both modes, diagnostics, async, and edge cases |
| test/PatternKit.Examples.Tests/Generators/FacadeSpecsTests.cs | 10 integration tests that unfortunately don't match the example implementations |
| src/PatternKit.Examples/Generators/Facade/BillingFacadeExample.cs | Billing system example coordinating tax, invoice, payment, and notification services |
| src/PatternKit.Examples/Generators/Facade/ShippingFacadeExample.cs | Shipping system example with rate calculation and validation |
| src/PatternKit.Examples/Generators/Facade/README.md | Example documentation with usage patterns (contains formatting errors) |
| docs/generators/facade.md | Comprehensive generator documentation with examples and best practices |
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@copilot apply changes based on the comments in this thread |
… improvements Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
…or behavior Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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@copilot apply changes based on the comments in this thread And make sure everything builds and tests successfully. It's currently failing. |
…type name conflicts Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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Implemented in commit 41ea473. All code review comments have been addressed: ✅ PKFCD003 (Duplicate Mappings) - Now detects and reports when multiple methods map to the same contract member The generator now has all 6 diagnostics (PKFCD001-006) fully implemented and tested. The remaining limitations (host-first dependency logic and contract-first signature matching) are design issues tracked for v2 as they require API changes. |
JerrettDavis
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Jan 23, 2026
Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #92 +/- ##
==========================================
+ Coverage 85.16% 89.59% +4.43%
==========================================
Files 146 152 +6
Lines 12954 13722 +768
Branches 1749 1879 +130
==========================================
+ Hits 11032 12294 +1262
+ Misses 1478 1428 -50
+ Partials 444 0 -444
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Pull request overview
Copilot reviewed 13 out of 13 changed files in this pull request and generated 10 comments.
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… handling, improve README Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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Applied in commit 9f59145. All code review comments addressed: ✅ Removed redundant All 1,717 tests passing across all frameworks. |
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Pull request overview
Copilot reviewed 13 out of 13 changed files in this pull request and generated 10 comments.
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…policy, and documentation Co-authored-by: JerrettDavis <2610199+JerrettDavis@users.noreply.github.com>
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Applied in commit f6f290b. Addressed critical issues: ✅ Fixed dependency name collisions with numeric disambiguation All 1,717 tests passing. Comments #2723309267 and #2723309271 (SignaturesMatch and host-first dependency detection) are tracked for v2 as they require API design changes. |
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Pull request overview
Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.
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Facade Pattern Generator - Critical Fixes
Changes Applied
Dependency Name Collision Fix (Comment #2723309249):
CollectDependenciesandCollectHostDependenciesValue Type Null Check Fix (Comment #2723309278):
?? throw new ArgumentNullExceptionfrom constructor assignmentsAsync Ignore Policy Fix (Comment #2723309275):
MissingMapPolicy.Ignorewith async methodsValueTask.CompletedTask,Task.CompletedTask, orFromResult(default!)as appropriateDocumentation Corrections (Comments #2723309257, #2723309264):
PaymentRequestandShipmentDetailscomplex type examplesAdded Helper Method:
GetAsyncReturnTypeto extract generic type argument from Task/ValueTaskTest Results
Remaining Known Limitations
SignaturesMatch strictness (Comment #2723309267):
Host-first dependency detection (Comment #2723309271):
Original prompt
This section details on the original issue you should resolve
<issue_title>Generator: Create Facade Pattern</issue_title>
<issue_description>## Summary
Add a source generator that produces boilerplate-free, GoF-consistent Facade pattern implementations for subsystems, enabling an explicit “front door” API over multiple collaborators.
The generator lives in
PatternKit.Generatorsand emits self-contained, readable C# with no runtime PatternKit dependency.Primary goals:
Motivation / Problem
Facade implementations are often:
A generator can:
Supported Targets (must-have)
The generator must support:
partial class/partial structpartial record class/partial record structFacade can be generated as:
Proposed User Experience
A) Contract-first facade (interface)
Generated (representative shape):
B) Host-first facade (mapping methods define surface)
Generated:
BillingFacadetype with instance methods, constructed withIBillingSubsystem.Attributes / Surface Area
Namespace:
PatternKit.Generators.FacadeCore
[GenerateFacade]on facade contract or hoststring? FacadeTypeName(default:<Name>Facade)bool GenerateAsync(default: inferred)bool ForceAsync(default: false)FacadeMissingMapPolicy MissingMap(default: Error)Mapping attributes:
[FacadeMap]identifies the implementation method backing a contract method.[FacadeExpose]identifies host methods to expose.[FacadeIgnore]excludes contract members.Policies:
MissingMapPolicy: Error | Stub (v2) | Ignore (discouraged)Semantics (must-have)
Deterministic mapping
Contract-first:
[FacadeMap]method.Host-first:
[FacadeExpose]method becomes a facade method.Async
ValueTask<T>/Task<T>or acceptsCancellationToken, emit async facade variants.ValueTaskfor generated async facade methods.Naming and organization
Keep generated code readable:
Diagnostics (must-have)
Stable IDs, actionable:
PKFCD001Type marked[GenerateFacade]must bepartial.PKFCD002No mapped methods found for facade members.PKFCD003Multiple mappings found for a single facade member.PKFCD004Map method signature mismatch.PKFCD005Facade type name conflicts with existing type.PKFCD006Async mapping detected but async generation disabled.Generated Code Layout
Name.Facade.g.csDeterminism:
Testing Expectations
Contract-first mapping routes to correct subsystem calls.
Host-first generates façade type correctly.
Async path respects cancellation.
Diagnostics:
Acceptance Criteria
[GenerateFacade]works for class/struct/record class/record struct (host) and supports interface contracts.💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.