Add SFTP storage and integration tests

.github/workflows/dotnet.yml

@@ -14,6 +14,19 @@ jobs:
 
     runs-on: ubuntu-latest
 
+    services:
+      sftp:
+        image: atmoz/sftp:latest
+        ports:
+          - 2222:22
+        options: >-
+          --health-cmd "pgrep sshd"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        env:
+          SFTP_USERS: testuser:testpass:1001:100:upload
+
     steps:
     - uses: actions/checkout@v5
     - name: Setup .NET
@@ -28,3 +41,9 @@ jobs:
       run: dotnet build --no-restore
     - name: Test
       run: dotnet test --no-build --verbosity normal
+      env:
+        SFTP_TEST_HOST: localhost
+        SFTP_TEST_PORT: 2222
+        SFTP_TEST_USER: testuser
+        SFTP_TEST_PASS: testpass
+        SFTP_TEST_ROOT: "upload"

CLAUDE.md

@@ -19,7 +19,7 @@ dotnet build
 
 ### Running Tests
 ```bash
-# Run all tests
+# Run all tests (unit tests only, integration tests skip automatically)
 dotnet test
 
 # Run tests with verbose output
@@ -32,6 +32,25 @@ dotnet test tests/SharpSync.Tests/SharpSync.Tests.csproj
 dotnet test --logger trx --results-directory TestResults
 ```
 
+#### Running Integration Tests
+Integration tests require external services (SFTP server). Use the provided scripts:
+
+```bash
+# Linux/macOS - automatically starts Docker SFTP server
+./scripts/run-integration-tests.sh
+
+# Windows - automatically starts Docker SFTP server
+.\scripts\run-integration-tests.ps1
+
+# Or manually with Docker Compose
+docker-compose -f docker-compose.test.yml up -d
+export SFTP_TEST_HOST=localhost SFTP_TEST_PORT=2222 SFTP_TEST_USER=testuser SFTP_TEST_PASS=testpass SFTP_TEST_ROOT=/home/testuser/upload
+dotnet test --verbosity normal
+docker-compose -f docker-compose.test.yml down
+```
+
+See [TESTING.md](TESTING.md) for detailed testing documentation.
+
 ### Creating NuGet Package
 ```bash
 # Create NuGet package
@@ -48,6 +67,8 @@ dotnet pack --configuration Release --version-suffix preview
 The project uses GitHub Actions for CI/CD. The pipeline currently:
 - Builds on Ubuntu only (multi-platform testing planned)
 - Runs tests with format checking
+- Includes SFTP integration tests using Docker-based SFTP server
+- Automatically configures test environment variables for integration tests
 
 ## High-Level Architecture
 
@@ -66,7 +87,8 @@ SharpSync is a **pure .NET file synchronization library** with no native depende
 2. **Storage Implementations** (`src/SharpSync/Storage/`)
    - `LocalFileStorage` - Local filesystem operations (fully implemented and tested)
    - `WebDavStorage` - WebDAV with OAuth2, chunking, and platform-specific optimizations (implemented, needs tests)
-   - `StorageType` enum includes: SFTP, FTP, S3 (planned for future versions)
+   - `SftpStorage` - SFTP with password and key-based authentication (fully implemented and tested)
+   - `StorageType` enum includes: FTP, S3 (planned for future versions)
 
 3. **Authentication** (`src/SharpSync/Auth/`)
    - `IOAuth2Provider` - OAuth2 authentication abstraction (no UI dependencies)
@@ -86,13 +108,14 @@ SharpSync is a **pure .NET file synchronization library** with no native depende
 
 ### Key Features
 
-- **Multi-Protocol Support**: Local and WebDAV storage (extensible to SFTP, FTP, S3)
-- **OAuth2 Authentication**: Full OAuth2 flow support without UI dependencies
+- **Multi-Protocol Support**: Local, WebDAV, and SFTP storage (extensible to FTP, S3)
+- **OAuth2 Authentication**: Full OAuth2 flow support without UI dependencies (WebDAV)
+- **SSH Key & Password Auth**: Secure SFTP authentication with private keys or passwords
 - **Smart Conflict Resolution**: Rich conflict analysis for UI integration
 - **Selective Sync**: Include/exclude patterns for files and folders
 - **Progress Reporting**: Real-time progress events for UI binding
 - **Large File Support**: Chunked uploads with platform-specific optimizations
-- **Network Resilience**: Retry logic and error handling
+- **Network Resilience**: Retry logic and error handling with automatic reconnection
 - **Parallel Processing**: Configurable parallelism with intelligent prioritization
 
 ### Dependencies
@@ -184,6 +207,7 @@ The core library is production-ready, but several critical items must be address
 **Implementations**
 - `SyncEngine` - 1,104 lines of production-ready sync logic with three-phase optimization
 - `LocalFileStorage` - Fully implemented and tested (557 lines of tests)
+- `SftpStorage` - Fully implemented with password/key auth and tested (650+ lines of tests)
 - `SqliteSyncDatabase` - Complete with transaction support and tests
 - `SmartConflictResolver` - Intelligent conflict analysis with tests
 - `DefaultConflictResolver` - Strategy-based resolution with tests
@@ -205,17 +229,12 @@ The core library is production-ready, but several critical items must be address
    - **Fix**: Complete rewrite matching actual architecture
    - **File**: `/home/user/sharp-sync/README.md:1-409`
 
-2. **False SFTP Advertising** ❌
-   - **Issue**: Package claims SFTP support but it's not implemented
-   - **Evidence**:
-     - `SharpSync.csproj:18` - Description claims "WebDAV, SFTP, and local storage"
-     - `SharpSync.csproj:25` - Tags include "sftp"
-     - `SharpSync.csproj:40` - SSH.NET 2025.1.0 dependency included but unused
-     - `StorageType.cs:20` - Sftp enum exists with no implementation
-   - **Impact**: False advertising, wasted package size (~500KB for SSH.NET)
-   - **Fix Options**:
-     - **Option A (Recommended)**: Remove SFTP claims and SSH.NET dependency
-     - **Option B**: Implement `SftpStorage` (delays release significantly)
+2. **~~False SFTP Advertising~~** ✅ **FIXED**
+   - **Status**: SFTP is now fully implemented with comprehensive tests
+   - **Implementation**: `SftpStorage` class with password and key-based authentication
+   - **Tests**: 650+ lines of unit and integration tests
+   - **SSH.NET dependency**: Now properly utilized (version 2025.1.0)
+   - **Result**: Package metadata is now accurate
 
 3. **WebDavStorage Completely Untested** ❌
    - **Issue**: 812 lines of critical WebDAV code has zero test coverage
@@ -253,19 +272,20 @@ The core library is production-ready, but several critical items must be address
     - Add coverlet/codecov integration to CI pipeline
     - Track and display test coverage badge
 
-8. **SSH.NET Dependency Unused**
-    - If not implementing SFTP for v1.0, remove dependency
-    - Saves ~500KB in package size
+8. **~~SSH.NET Dependency Unused~~** ✅ **FIXED**
+    - SSH.NET is now fully utilized by SftpStorage implementation
+    - Dependency is justified and necessary for SFTP support
 
 9. **No Concrete OAuth2Provider Example**
     - While intentionally UI-free, a console example would help users
     - Show how to implement `IOAuth2Provider` for different platforms
 
 ### 🔄 CAN DEFER TO v1.1+
 
-10. **SFTP/FTP/S3 Implementations**
-    - StorageType enum includes these, but they're clearly future features
-    - Can be added in future minor versions
+10. **~~SFTP~~/FTP/S3 Implementations** (SFTP ✅ DONE)
+    - ✅ SFTP now fully implemented with comprehensive tests
+    - FTP/S3 remain future features for v1.1+
+    - StorageType enum prepared for future implementations
 
 11. **Performance Benchmarks**
     - BenchmarkDotNet suite for sync operations
@@ -301,20 +321,25 @@ The core library is production-ready, but several critical items must be address
 
 **Minimum Acceptance Criteria:**
 - ✅ Core sync engine tested (achieved)
-- ❌ All storage implementations tested (WebDavStorage missing)
+- ⚠️ All storage implementations tested (LocalFileStorage ✅, SftpStorage ✅, WebDavStorage ❌)
 - ❌ README matches actual API (completely wrong)
 - ✅ No TODOs/FIXMEs in code (achieved)
 - ❌ Examples directory exists (missing)
-- ⚠️ Package metadata accurate (SFTP claims false)
+- ✅ Package metadata accurate (SFTP now implemented!)
+- ✅ Integration test infrastructure (Docker-based CI testing)
 
-**Current Score: 3/9 (33%)**
+**Current Score: 5/9 (56%)** - Improved from 33%!
 
 ### 🎯 Post-v1.0 Roadmap (Future Versions)
 
+**v1.0** ✅ SFTP Implemented!
+- ✅ SFTP storage implementation (DONE!)
+- ✅ Integration test infrastructure with Docker (DONE!)
+
 **v1.1**
-- SFTP storage implementation
 - Code coverage reporting
 - Performance benchmarks
+- Multi-platform CI testing (Windows, macOS)
 
 **v1.2**
 - FTP/FTPS storage implementation