feat(tests): add integration tests for publish functionality and enhance error handling

integrationtests/README.md

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+# Integration Tests
+
+This directory contains integration tests for the MCP Registry API using the fake service implementation.
+
+## Overview
+
+The integration tests are designed to test the complete flow of the publish endpoint using real service implementations (fake service) rather than mocks. This provides confidence that the entire request/response cycle works correctly.
+
+## Test Structure
+
+### `publish_integration_test.go`
+
+Contains comprehensive integration tests for the publish endpoint:
+
+- **TestPublishIntegration**: Tests various scenarios for publishing servers
+  - Successful publish with GitHub authentication
+  - Successful publish without authentication (for non-GitHub servers)
+  - Error cases: missing name, missing version, missing auth header, invalid JSON, unsupported HTTP methods
+  - Duplicate package handling: fails when same name+version, succeeds with different versions
+
+- **TestPublishIntegrationWithComplexPackages**: Tests publishing servers with complex package configurations
+  - Multiple runtime arguments (named and positional)
+  - Package arguments
+  - Environment variables (including secrets)
+  - Multiple remotes with different transport types
+  - Headers for HTTP remotes
+
+- **TestPublishIntegrationEndToEnd**: Tests the complete end-to-end flow
+  - Publishes a server and verifies it can be retrieved
+  - Checks that the server appears in the registry list
+  - Verifies count consistency
+
+## Mock Services
+
+### MockAuthService
+
+A simple mock implementation of the `auth.Service` interface that:
+- Accepts any non-empty token for GitHub authentication
+- Always allows authentication for `AuthMethodNone`
+- Provides realistic responses for auth flow methods
+
+## Running the Tests
+
+From the project root directory:
+
+```bash
+# Run all integration tests
+go test ./integrationtests/...
+
+# Run with verbose output
+go test -v ./integrationtests/...
+
+# Run a specific test
+go test -v ./integrationtests/ -run TestPublishIntegration
+
+# Run tests with race detection
+go test -race ./integrationtests/...
+
+# Use the convenient test runner script
+./integrationtests/run_tests.sh
+```
+
+## Test Data
+
+The tests use the fake service which comes pre-populated with sample data:
+- 3 sample MCP servers with different configurations
+- Uses in-memory database for isolation between tests
+- Each test creates unique server instances with UUIDs
+
+## Benefits of Integration Tests
+
+1. **Real Flow Testing**: Tests the actual HTTP request/response cycle
+2. **Service Integration**: Validates that handlers work correctly with service implementations
+3. **Data Persistence**: Verifies that published data can be retrieved
+4. **Error Handling**: Tests complete error scenarios end-to-end
+5. **Complex Scenarios**: Tests realistic server configurations with packages and remotes
+
+## Dependencies
+
+These tests use:
+- `testify/assert` and `testify/require` for assertions
+- `httptest` for HTTP testing utilities
+- The fake service implementation for realistic data operations
+- Standard Go testing package
+
+## Test Coverage
+
+The integration tests cover:
+- ✅ Successful publish scenarios
+- ✅ Authentication validation
+- ✅ Input validation
+- ✅ Duplicate package handling
+- ✅ Complex package configurations
+- ✅ Multiple remotes
+- ✅ Error handling
+- ✅ End-to-end data flow
+- ✅ HTTP method validation
+- ✅ JSON parsing errors