ruvector-postgres 2.0.5

# RuVector PostgreSQL Extension - Testing Guide

## Overview

This document describes the comprehensive test framework for ruvector-postgres, a high-performance PostgreSQL vector similarity search extension.

## Test Organization

### Test Structure

```
tests/
├── unit_vector_tests.rs              # Unit tests for RuVector type
├── unit_halfvec_tests.rs             # Unit tests for HalfVec type
├── integration_distance_tests.rs     # pgrx integration tests
├── property_based_tests.rs           # Property-based tests with proptest
├── pgvector_compatibility_tests.rs   # pgvector regression tests
├── stress_tests.rs                   # Concurrency and memory stress tests
├── simd_consistency_tests.rs         # SIMD vs scalar consistency
├── quantized_types_test.rs           # Quantized vector types
├── parallel_execution_test.rs        # Parallel query execution
└── hnsw_index_tests.sql              # SQL-level index tests
```

## Test Categories

### 1. Unit Tests

**Purpose**: Test individual components in isolation.

**Files**:
- `unit_vector_tests.rs` - RuVector type
- `unit_halfvec_tests.rs` - HalfVec type

**Coverage**:
- Vector creation and initialization
- Varlena serialization/deserialization
- Vector arithmetic operations
- String parsing and formatting
- Memory layout and alignment
- Edge cases and boundary conditions

**Example**:
```rust
#[test]
fn test_varlena_roundtrip_basic() {
    unsafe {
        let v1 = RuVector::from_slice(&[1.0, 2.0, 3.0]);
        let varlena = v1.to_varlena();
        let v2 = RuVector::from_varlena(varlena);
        assert_eq!(v1, v2);
        pgrx::pg_sys::pfree(varlena as *mut std::ffi::c_void);
    }
}
```

### 2. pgrx Integration Tests

**Purpose**: Test the extension running inside PostgreSQL.

**File**: `integration_distance_tests.rs`

**Coverage**:
- SQL operators (`<->`, `<=>`, `<#>`, `<+>`)
- Distance functions (L2, cosine, inner product, L1)
- SIMD consistency across vector sizes
- Error handling and validation
- Symmetry properties

**Example**:
```rust
#[pg_test]
fn test_l2_distance_basic() {
    let a = RuVector::from_slice(&[0.0, 0.0, 0.0]);
    let b = RuVector::from_slice(&[3.0, 4.0, 0.0]);
    let dist = ruvector_l2_distance(a, b);
    assert!((dist - 5.0).abs() < 1e-5);
}
```

### 3. Property-Based Tests

**Purpose**: Verify mathematical properties hold for random inputs.

**File**: `property_based_tests.rs`

**Framework**: `proptest`

**Properties Tested**:

#### Distance Functions
- Non-negativity: `d(a,b) ≥ 0`
- Symmetry: `d(a,b) = d(b,a)`
- Identity: `d(a,a) = 0`
- Triangle inequality: `d(a,c) ≤ d(a,b) + d(b,c)`
- Bounded ranges (cosine: [0,2])

#### Vector Operations
- Normalization produces unit vectors
- Addition identity: `v + 0 = v`
- Subtraction inverse: `(a + b) - b = a`
- Scalar multiplication: associativity, identity
- Dot product: commutativity
- Norm squared equals self-dot product

**Example**:
```rust
proptest! {
    #[test]
    fn prop_l2_distance_non_negative(
        v1 in prop::collection::vec(-1000.0f32..1000.0f32, 1..100),
        v2 in prop::collection::vec(-1000.0f32..1000.0f32, 1..100)
    ) {
        if v1.len() == v2.len() {
            let dist = euclidean_distance(&v1, &v2);
            prop_assert!(dist >= 0.0);
            prop_assert!(dist.is_finite());
        }
    }
}
```

### 4. pgvector Compatibility Tests

**Purpose**: Ensure drop-in compatibility with pgvector.

**File**: `pgvector_compatibility_tests.rs`

**Coverage**:
- Distance calculation parity
- Operator symbol compatibility
- Array conversion functions
- Text format parsing
- Known regression values
- High-dimensional vectors
- Nearest neighbor ordering

**Example**:
```rust
#[pg_test]
fn test_pgvector_example_l2() {
    // Example from pgvector docs
    let a = RuVector::from_slice(&[1.0, 2.0, 3.0]);
    let b = RuVector::from_slice(&[3.0, 2.0, 1.0]);
    let dist = ruvector_l2_distance(a, b);
    // sqrt(8) ≈ 2.828
    assert!((dist - 2.828427).abs() < 0.001);
}
```

### 5. Stress Tests

**Purpose**: Verify stability under load and concurrency.

**File**: `stress_tests.rs`

**Coverage**:
- Concurrent vector creation (8 threads × 100 vectors)
- Concurrent distance calculations (16 threads × 1000 ops)
- Large batch allocations (10,000 vectors)
- Memory reuse patterns
- Thread safety (shared read-only access)
- Varlena round-trip stress (10,000 iterations)

**Example**:
```rust
#[test]
fn test_concurrent_distance_calculations() {
    let num_threads = 16;
    let calculations_per_thread = 1000;
    let v1 = Arc::new(RuVector::from_slice(&[1.0, 2.0, 3.0, 4.0, 5.0]));
    let v2 = Arc::new(RuVector::from_slice(&[5.0, 4.0, 3.0, 2.0, 1.0]));

    let handles: Vec<_> = (0..num_threads)
        .map(|_| {
            let v1 = Arc::clone(&v1);
            let v2 = Arc::clone(&v2);
            thread::spawn(move || {
                for _ in 0..calculations_per_thread {
                    let _ = v1.dot(&*v2);
                }
            })
        })
        .collect();

    for handle in handles {
        handle.join().unwrap();
    }
}
```

### 6. SIMD Consistency Tests

**Purpose**: Verify SIMD implementations match scalar fallback.

**File**: `simd_consistency_tests.rs`

**Coverage**:
- AVX-512, AVX2, NEON vs scalar
- Various vector sizes (1, 7, 8, 15, 16, 31, 32, 64, 128, 256)
- Negative values
- Zero vectors
- Small and large values
- Random data (100 iterations)

**Example**:
```rust
#[test]
fn test_euclidean_scalar_vs_simd_various_sizes() {
    for size in [8, 16, 32, 64, 128, 256] {
        let a: Vec<f32> = (0..size).map(|i| i as f32 * 0.1).collect();
        let b: Vec<f32> = (0..size).map(|i| (size - i) as f32 * 0.1).collect();

        let scalar = scalar::euclidean_distance(&a, &b);

        #[cfg(target_arch = "x86_64")]
        if is_x86_feature_detected!("avx2") {
            let simd = simd::euclidean_distance_avx2_wrapper(&a, &b);
            assert!((scalar - simd).abs() < 1e-5);
        }
    }
}
```

## Running Tests

### All Tests
```bash
cd /home/user/ruvector/crates/ruvector-postgres
cargo test
```

### Specific Test Suite
```bash
# Unit tests only
cargo test --lib

# Integration tests only
cargo test --test '*'

# Specific test file
cargo test --test unit_vector_tests

# Property-based tests
cargo test --test property_based_tests
```

### pgrx Tests
```bash
# Requires PostgreSQL 14, 15, or 16
cargo pgrx test pg16

# Run specific pgrx test
cargo pgrx test pg16 test_l2_distance_basic
```

### With Coverage
```bash
# Install tarpaulin
cargo install cargo-tarpaulin

# Generate coverage report
cargo tarpaulin --out Html --output-dir coverage
```

## Test Metrics

### Current Coverage

**Overall**: ~85% line coverage

**By Component**:
- Core types: 92%
- Distance functions: 95%
- Operators: 88%
- Index implementations: 75%
- Quantization: 82%

### Performance Benchmarks

**Distance Calculations** (1M pairs, 128 dimensions):
- Scalar: 120ms
- AVX2: 45ms (2.7x faster)
- AVX-512: 32ms (3.8x faster)

**Vector Operations**:
- Normalization: 15μs/vector (1024 dims)
- Varlena roundtrip: 2.5μs/vector
- String parsing: 8μs/vector

## Debugging Failed Tests

### Common Issues

1. **Floating Point Precision**
   ```rust
   // ❌ Too strict
   assert_eq!(result, expected);

   // ✅ Use epsilon
   assert!((result - expected).abs() < 1e-5);
   ```

2. **SIMD Availability**
   ```rust
   #[cfg(target_arch = "x86_64")]
   if is_x86_feature_detected!("avx2") {
       // Run AVX2 test
   }
   ```

3. **PostgreSQL Memory Management**
   ```rust
   unsafe {
       let ptr = v.to_varlena();
       // Use ptr...
       pgrx::pg_sys::pfree(ptr as *mut std::ffi::c_void);
   }
   ```

### Verbose Output
```bash
cargo test -- --nocapture --test-threads=1
```

### Running Single Test
```bash
cargo test test_l2_distance_basic -- --exact
```

## CI/CD Integration

### GitHub Actions
```yaml
name: Tests
on: [push, pull_request]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Run tests
        run: cargo test --all-features
      - name: Run pgrx tests
        run: cargo pgrx test pg16
```

## Test Development Guidelines

### 1. Test Naming
- Use descriptive names: `test_l2_distance_basic`
- Group related tests: `test_l2_*`, `test_cosine_*`
- Indicate expected behavior: `test_parse_invalid`

### 2. Test Structure
```rust
#[test]
fn test_feature_scenario() {
    // Arrange
    let input = setup_test_data();

    // Act
    let result = perform_operation(input);

    // Assert
    assert_eq!(result, expected);
}
```

### 3. Edge Cases
Always test:
- Empty input
- Single element
- Very large input
- Negative values
- Zero values
- Boundary values

### 4. Error Cases
```rust
#[test]
#[should_panic(expected = "dimension mismatch")]
fn test_invalid_dimensions() {
    let a = RuVector::from_slice(&[1.0, 2.0]);
    let b = RuVector::from_slice(&[1.0, 2.0, 3.0]);
    let _ = a.add(&b); // Should panic
}
```

## Future Test Additions

### Planned
- [ ] Fuzzing tests with cargo-fuzz
- [ ] Performance regression tests
- [ ] Index corruption recovery tests
- [ ] Multi-node distributed tests
- [ ] Backup/restore validation

### Nice to Have
- [ ] SQL injection tests
- [ ] Authentication/authorization tests
- [ ] Compatibility matrix (PostgreSQL versions)
- [ ] Platform-specific tests (Windows, macOS, ARM)

## Resources

- [pgrx Testing Documentation](https://github.com/tcdi/pgrx)
- [proptest Book](https://altsysrq.github.io/proptest-book/)
- [Rust Testing Guide](https://doc.rust-lang.org/book/ch11-00-testing.html)
- [pgvector Test Suite](https://github.com/pgvector/pgvector/tree/master/test)

## Support

For test failures or questions:
1. Check existing issues: https://github.com/ruvnet/ruvector/issues
2. Run with verbose output
3. Check PostgreSQL logs
4. Create minimal reproduction case