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docs/old-network-planning/PHASE_0.md

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+# Phase 0: Environment Setup
+
+## Overview
+
+This phase focuses on establishing the development and testing infrastructure necessary for implementing the network library. A robust testing environment is critical for a complex system like this, as it will allow for proper verification of functionality, edge case handling, and performance characteristics.
+
+## Detailed Requirements
+
+### 1. Jest Configuration Setup
+
+#### Base Configuration
+
+Create a Jest configuration that:
+
+- Uses the appropriate preset for the project
+- Transforms TypeScript files correctly
+- Sets up coverage reporting to track test coverage
+- Specifies files to include/exclude from coverage
+- Enforces 100% coverage thresholds for all metrics
+- Configures any additional plugins or test environments needed
+
+#### Jest Setup File
+
+Create a setup file that:
+
+- Imports necessary testing libraries
+- Sets up custom matchers for network-specific assertions
+- Configures global timeout settings appropriate for network tests
+- Sets up any mocks that should be present for all tests
+
+### 2. TypeScript Configuration
+
+Ensure TypeScript configuration supports both the library implementation and testing:
+
+- Library configuration should enable declaration file generation
+- Test configuration should support Jest and CommonJS modules
+- Both configurations should share base settings for consistency
+- Ensure proper exclusion patterns to prevent cross-contamination
+
+### 3. Testing Utilities
+
+#### Network Mocks
+
+Create mock implementations of key interfaces:
+
+- **MockNetworkNode**: A simplified version of NetworkNode for testing
+  - Should expose basic properties/methods needed for testing
+  - Should simulate basic node behavior
+  - Should provide helpers for simulating events/state changes
+  - Should expose protected methods/properties for testing
+
+- **TestEventEmitter**: An implementation of IEventEmitter for testing
+  - Should track emitted events
+  - Should allow inspection of event history
+  - Should support standard event subscription/unsubscription
+  - Should provide helper methods for test assertions
+
+#### Network Testing Harness
+
+Create a comprehensive testing harness that:
+
+- Provides methods to create test networks easily
+- Supports creation of various network topologies
+- Offers utilities for connection/disconnection simulation
+- Includes helpers for message passing verification
+- Provides reset functionality for test isolation
+
+#### Time-Based Testing Helpers
+
+Create utilities for time-dependent tests:
+
+- Methods for controlled delays in async tests
+- Utilities for Jest timer manipulation
+- Tools for waiting on conditions with timeouts
+- Helpers for testing time-sensitive operations
+
+#### Assertion Helpers
+
+Create specialized assertion utilities:
+
+- Node relationship assertions
+- Message validation assertions
+- Event emission assertions
+- Network state assertions
+
+## Testing Strategy Requirements
+
+### Test Isolation
+
+Tests must be properly isolated to prevent side effects:
+
+- Each test should start with a fresh environment
+- Mocks and spies should be cleared between tests
+- Shared state should be reset before each test
+- External dependencies should be properly mocked
+
+### Asynchronous Testing
+
+Since many network operations are asynchronous, the test framework should support:
+
+- Async/await pattern for test cases
+- Proper handling of promises in assertions
+- Utilities for controlled timing and synchronization
+- Methods for waiting for asynchronous operations to complete
+
+### Time-Dependent Testing
+
+For testing time-sensitive behavior:
+
+- Support Jest's fake timer utilities
+- Provide helpers for manipulating simulated time
+- Include utilities for testing delays and timeouts
+- Support both real and simulated time depending on test needs
+
+## Directory Structure
+
+Establish a directory structure that supports the development approach:
+
+```text
+libs/network/
+├── jest.config.ts
+├── jest.setup.ts
+├── tsconfig.json
+├── tsconfig.lib.json
+├── tsconfig.spec.json
+├── src/
+│   ├── testing/
+│   │   ├── mocks/
+│   │   │   ├── network-node.mock.ts
+│   │   │   ├── transport.mock.ts
+│   │   │   └── ... other mocks
+│   │   ├── network-test-harness.ts
+│   │   ├── time-helpers.ts
+│   │   ├── assertions.ts
+│   │   └── index.ts
+│   └── ... other directories
+```
+
+## Interface Requirements
+
+The testing utilities should adhere to these interfaces:
+
+### Test Harness Interface
+
+The test harness should provide:
+
+- Methods to create individual nodes with specified capabilities
+- Methods to create multiple nodes at once
+- Methods to establish connections between nodes
+- Methods to simulate disconnections
+- Methods to retrieve nodes by ID
+- Methods to get all nodes in the test network
+- Methods to reset the test environment
+
+### Mock Node Interface
+
+Mock nodes should implement:
+
+- Core properties of real nodes (id, level, etc.)
+- Methods to simulate network events
+- Methods to expose normally protected functionality
+- Simplified versions of core node behavior
+
+### Test Event Emitter Interface
+
+The test event emitter should implement:
+
+- Standard event subscription/unsubscription
+- Event emission
+- Methods to query event history
+- Methods to clear event history
+- Methods to check for specific events
+
+## Edge Cases and Considerations
+
+### 1. Test Isolation
+
+Tests must be completely isolated to prevent interference:
+
+- Ensure stateful components are reset between tests
+- Verify that events from one test don't affect others
+- Make sure asynchronous operations complete properly
+- Ensure timers are properly cleaned up
+
+### 2. Asynchronous Testing
+
+Async tests require special handling:
+
+- Define strategies for testing async message delivery
+- Create patterns for verifying eventual consistency
+- Establish timeout guidelines for different test types
+- Document patterns for avoiding race conditions in tests
+
+### 3. Mock Limitations
+
+Be clear about mock limitations:
+
+- Document differences between mocks and real implementations
+- Establish which behaviors are simulated vs. delegated
+- Define which edge cases might not be properly tested with mocks
+- Create guidelines for when to use mocks vs. real components
+
+### 4. Time-Sensitive Testing
+
+Establish approaches for time-sensitive tests:
+
+- Define when to use real timers vs. fake timers
+- Create patterns for testing timeout behavior
+- Document approaches for testing retry logic
+- Establish strategies for testing debounce/throttle behavior
+
+## Deliverables
+
+1. Complete Jest configuration files
+2. TypeScript configuration files for library and tests
+3. Core testing utilities:
+   - Network test harness
+   - Mock implementations
+   - Testing helpers
+   - Assertion utilities
+4. Documentation on testing approaches and patterns
+
+## Success Criteria
+
+Phase 0 is complete when:
+
+- All testing infrastructure is in place
+- Test utilities are themselves thoroughly tested
+- Example tests demonstrate proper isolation and robustness
+- TypeScript compilation works without errors
+- Jest coverage reporting is properly configured
+- Documentation clearly explains the testing approach
+
+This phase sets up the foundation for all subsequent development phases, ensuring that we can effectively test the complex network components we will build.