hackathon/docs/testing/test-strategy.md

# Test Strategy - Log Data Collector

## Overview

This document defines the comprehensive testing strategy for the Log Data Collector system, ensuring full validation of functional, non-functional, architectural, and normative requirements.

## Test Framework Stack

### Core Testing Tools
- **JUnit 5** (Jupiter) - Unit and integration testing framework (Req-NFR-9)
- **Mockito 5.x** - Mocking framework for dependencies (Req-NFR-9)
- **Maven Surefire** - Unit test execution (Req-NFR-10)
- **Maven Failsafe** - Integration test execution (Req-NFR-10)

### Mock Servers
- **WireMock** - Mock HTTP server for endpoint simulation (Req-NFR-7)
- **gRPC Testing** - In-process gRPC server for transmission testing (Req-NFR-8)

### Additional Tools
- **AssertJ** - Fluent assertions for better readability
- **Awaitility** - Asynchronous test support
- **JMH** - Java Microbenchmark Harness for performance testing

## Test Pyramid Structure

```
                 /\
                /E2E\          5% - End-to-End (Full system)
               /------\
              /Integr. \       20% - Integration (Component interaction)
             /----------\
            /   Unit     \     75% - Unit (Individual components)
           /--------------\
```

## Test Categories

### 1. Unit Tests (75% of test suite)

**Scope**: Individual components in isolation with mocked dependencies

**Coverage Target**: 90% line coverage, 85% branch coverage

**Test Classes**:
- `ConfigurationLoaderTest` - Configuration parsing and validation
- `DataSerializerTest` - JSON/Protocol Buffer serialization
- `CircularBufferTest` - Buffer operations and thread safety
- `RetryMechanismTest` - Retry logic and backoff strategies
- `HealthCheckEndpointTest` - Health check HTTP/gRPC responses
- `HttpCollectorTest` - HTTP endpoint collection logic
- `GrpcTransmitterTest` - gRPC transmission logic
- `StartupSequenceTest` - Application startup orchestration

**Characteristics**:
- Fast execution (< 100ms per test)
- No external dependencies
- Deterministic results
- Isolated failures

### 2. Integration Tests (20% of test suite)

**Scope**: Component interactions with real infrastructure (mocked external systems)

**Coverage Target**: Key integration paths and data flows

**Test Classes**:
- `HttpCollectionIntegrationTest` - HTTP collection with WireMock server
- `GrpcTransmissionIntegrationTest` - gRPC transmission with test server
- `EndToEndDataFlowTest` - Complete IF1 → IF2 data pipeline
- `ConfigurationFileIntegrationTest` - Real YAML file loading
- `CircularBufferIntegrationTest` - Multi-threaded buffer operations

**Characteristics**:
- Moderate execution time (< 5s per test)
- Real component interaction
- Mock external systems only
- Controlled test environment

### 3. End-to-End Tests (5% of test suite)

**Scope**: Full system validation with all components running

**Coverage Target**: Critical user scenarios and requirement validation

**Test Scenarios**:
- `E2EStartupAndCollectionTest` - Complete startup and first collection
- `E2EFailureRecoveryTest` - System resilience under failures
- `E2EPerformanceTest` - Load testing with 1000 endpoints
- `E2EConfigurationReloadTest` - Runtime configuration updates

**Characteristics**:
- Longer execution (< 30s per test)
- Real system deployment
- End-user perspective
- High-level validation

### 4. Performance Tests

**Scope**: Non-functional requirement validation

**Test Classes**:
- `PerformanceConcurrentEndpointsTest` - 1000 concurrent endpoints (Req-NFR-1)
- `PerformanceMemoryUsageTest` - Memory consumption < 4096MB (Req-NFR-2)
- `PerformanceVirtualThreadTest` - Virtual thread efficiency (Req-Arch-6)
- `PerformanceStartupTimeTest` - Startup time measurements

**Execution**: Separate Maven profile (`performance`) for CI/CD integration

### 5. Reliability Tests

**Scope**: Failure scenarios and recovery mechanisms

**Test Classes**:
- `ReliabilityStartupSequenceTest` - Startup component ordering (Req-FR-1 to Req-FR-8)
- `ReliabilityGrpcRetryTest` - gRPC connection failures (Req-FR-6, Req-FR-29)
- `ReliabilityHttpFailureTest` - HTTP endpoint failures (Req-FR-20)
- `ReliabilityBufferOverflowTest` - Buffer overflow handling (Req-FR-26)
- `ReliabilityPartialFailureTest` - Subset endpoint failures

**Execution**: Part of regular test suite with failure injection

### 6. Compliance Tests

**Scope**: Normative requirement validation

**Test Classes**:
- `ComplianceErrorDetectionTest` - Error detection mechanisms (Req-Norm-3)
- `ComplianceIso9001Test` - ISO-9001 quality measures (Req-Norm-1)
- `ComplianceEn50716Test` - EN 50716 software measures (Req-Norm-2)
- `ComplianceAuditLoggingTest` - Audit trail verification

**Execution**: Automated compliance report generation

## Test Data Management

### Test Configuration Files
- `src/test/resources/test-config.yaml` - Valid test configuration
- `src/test/resources/test-config-invalid.yaml` - Invalid format testing
- `src/test/resources/test-config-minimal.yaml` - Minimal valid config
- `src/test/resources/test-config-maximal.yaml` - Maximum complexity config

### Test Data Generators
- `TestDataFactory` - Create test log entries
- `TestConfigurationBuilder` - Fluent configuration creation
- `TestEndpointBuilder` - HTTP/gRPC endpoint creation

### Mock Server Definitions
- `HttpMockServerSetup` - WireMock server configuration
- `GrpcMockServerSetup` - gRPC test server configuration

## Test Execution Strategy

### Local Development
```bash
# Run all unit tests
mvn test

# Run integration tests
mvn verify -P integration-tests

# Run performance tests
mvn verify -P performance-tests

# Run all tests with coverage
mvn verify -P all-tests jacoco:report
```

### CI/CD Pipeline
1. **Commit Stage**: Unit tests (fast feedback)
2. **Integration Stage**: Integration tests + unit tests
3. **Performance Stage**: Performance tests (nightly)
4. **Compliance Stage**: Compliance validation + audit report

### Test Execution Order
1. Unit tests (parallel execution)
2. Integration tests (sequential by category)
3. E2E tests (sequential)
4. Performance tests (isolated environment)

## Assertion Strategy

### Unit Tests
```java
// Use AssertJ for fluent assertions
assertThat(config.getEndpoints())
    .isNotEmpty()
    .hasSize(3)
    .allMatch(e -> e.getUrl() != null);

// Verify mock interactions
verify(grpcClient, times(1)).sendLogData(any());
verifyNoMoreInteractions(grpcClient);
```

### Integration Tests
```java
// Await asynchronous results
await().atMost(5, SECONDS)
    .untilAsserted(() ->
        assertThat(buffer.size()).isGreaterThan(0));

// Verify WireMock interactions
wireMock.verify(exactly(1),
    getRequestedFor(urlEqualTo("/health")));
```

### Performance Tests
```java
// JMH benchmark assertions
assertThat(result.getScore())
    .isLessThan(1000); // ops/ms threshold

// Memory assertions
assertThat(memoryUsed)
    .isLessThan(4096 * 1024 * 1024L); // 4096 MB
```

## Coverage Requirements

### Minimum Coverage Thresholds
- **Line Coverage**: 85% overall, 90% for critical components
- **Branch Coverage**: 80% overall, 85% for decision logic
- **Method Coverage**: 90% overall

### Excluded from Coverage
- Generated code (Protocol Buffers, builders)
- Main entry points (`public static void main`)
- Exception constructors
- Trivial getters/setters

### Coverage Tools
- **JaCoCo** - Code coverage measurement
- **SonarQube** - Coverage analysis and technical debt tracking

## Test Naming Convention

### Unit Tests
```
should{ExpectedBehavior}_when{Condition}_given{State}

Examples:
- shouldReturnConfiguration_whenFileExists_givenValidYaml()
- shouldThrowException_whenFileNotFound_givenInvalidPath()
```

### Integration Tests
```
should{IntegrateComponents}_when{Scenario}_given{Setup}

Examples:
- shouldCollectData_whenHttpEndpointResponds_givenMockServer()
- shouldRetryTransmission_whenGrpcFails_givenRetryPolicy()
```

### Performance Tests
```
should{MeetRequirement}_when{LoadCondition}_given{SystemState}

Examples:
- shouldHandleConcurrentEndpoints_whenLoading1000Endpoints_givenVirtualThreads()
- shouldStayWithinMemoryLimit_whenBufferFull_givenMaxCapacity()
```

## Mock Strategy

### What to Mock
- External HTTP endpoints (WireMock)
- gRPC server connections (in-process test server)
- File system operations (optional, prefer test files)
- Time-dependent operations (Clock abstraction)

### What NOT to Mock
- Domain objects (value objects, entities)
- In-memory data structures (test real implementation)
- Simple utilities (no behavior to mock)
- Configuration objects (use test builders)

### Mockito Patterns
```java
// Stub return values
when(configLoader.load(anyString()))
    .thenReturn(testConfiguration);

// Verify interactions
verify(transmitter).send(argThat(data ->
    data.getTimestamp().isAfter(testStart)));

// Spy on real objects
ConfigurationLoader spy = spy(realConfigLoader);
doReturn(testConfig).when(spy).loadFromFile(any());
```

## Test Environment Setup

### Test Resources
```
src/test/
├── java/
│   └── com/logcollector/
│       ├── unit/           # Unit tests
│       ├── integration/    # Integration tests
│       ├── e2e/           # End-to-end tests
│       ├── performance/   # Performance tests
│       └── util/          # Test utilities
└── resources/
    ├── test-config.yaml
    ├── logback-test.xml   # Test logging config
    └── mockito-extensions/
```

### Test Fixtures
- `@BeforeEach` - Test-specific setup
- `@BeforeAll` - Class-level setup (expensive resources)
- `@AfterEach` - Test cleanup
- `@AfterAll` - Class-level cleanup

### Test Isolation
- Each test creates its own data
- No shared mutable state between tests
- Independent test execution order
- Parallel test execution where possible

## Continuous Testing

### Pre-Commit Hooks
- Run unit tests locally
- Verify code style (Checkstyle)
- Static analysis (SpotBugs)

### CI/CD Integration
- Automated test execution on every commit
- Coverage trend tracking
- Performance regression detection
- Test failure notifications

### Test Reporting
- JUnit XML reports for CI tools
- HTML coverage reports (JaCoCo)
- Test execution time tracking
- Flaky test detection

## Requirement Traceability

Every test class includes Javadoc with requirement mapping:

```java
/**
 * Tests for ConfigurationLoader component.
 *
 * @validates Req-FR-11 - Configuration file detection
 * @validates Req-FR-12 - Configuration parsing
 * @validates Req-FR-13 - Configuration validation
 * @validates Req-Norm-3 - Error detection
 */
@DisplayName("Configuration Loader Tests")
class ConfigurationLoaderTest {
    // Test methods...
}
```

See `test-requirement-mapping.md` for complete test-to-requirement matrix.

## Test Maintenance

### Test Review Criteria
- ✓ Clear test naming
- ✓ Single assertion focus
- ✓ Requirement traceability
- ✓ Fast execution (< 100ms for unit)
- ✓ Deterministic results
- ✓ Meaningful failure messages

### Test Refactoring
- Extract common setup to test utilities
- Use test builders for complex objects
- Parameterize similar test scenarios
- Remove duplicate assertions

### Test Debt Management
- Track flaky tests
- Identify slow tests
- Monitor coverage trends
- Refactor brittle tests

## Success Metrics

### Test Quality Metrics
- **Test Coverage**: > 85% line coverage
- **Test Execution Time**: < 5 minutes for full suite
- **Test Stability**: < 1% flaky test rate
- **Bug Escape Rate**: < 5% defects found in production

### Test Effectiveness Metrics
- **Defect Detection Rate**: Tests catch 95%+ of bugs before production
- **Requirement Coverage**: 100% of requirements validated by tests
- **Regression Prevention**: Zero regression bugs in covered areas

## References

- JUnit 5 User Guide: https://junit.org/junit5/docs/current/user-guide/
- Mockito Documentation: https://javadoc.io/doc/org.mockito/mockito-core
- WireMock Documentation: https://wiremock.org/docs/
- gRPC Testing Guide: https://grpc.io/docs/languages/java/basics/#testing
- JaCoCo Documentation: https://www.jacoco.org/jacoco/trunk/doc/

---

**Version**: 1.0
**Last Updated**: 2025-11-19
**Author**: Test Strategist Agent
**Approval**: Pending Architecture Review