Experiment: SQLx-based testing approach for EQL

[tobyhede]

Overview

This is an experimental branch exploring SQLx (Rust) as an alternative testing approach for EQL, with comprehensive analysis comparing different testing frameworks.

⚠️ Note: This branch contains an alternative approach to PR #135 (pgTAP testing). It's meant for evaluation and discussion, not immediate merging.

What's Included

1. SQLx/Rust Testing Infrastructure

• rust-tests/ directory with Cargo project
• Example test: add_column_test.rs demonstrating Rust+SQLx testing patterns
• Test runner script: rust-tests/run-tests.sh
• Async test support with connection pooling

2. Comprehensive Documentation

TESTING_FRAMEWORK_COMPARISON.md (597 lines)

Detailed analysis of testing approaches:

• pgTAP: PostgreSQL-native testing (SQL-based)
• SQLx/Rust: Type-safe testing with Rust
• Component System: Previous attempt at Rust-based tooling
• Side-by-side comparisons with examples
• Pros/cons for each approach
• Recommendations based on project needs

SQLX_TESTING_APPROACH.md (155 lines)

• Problem statement: Why the Rust component system was too complex
• Proposed solution: Use SQLx for tests, keep bash for builds
• Architecture comparison
• Clear separation of concerns

3. Example Test

rust-tests/tests/add_column_test.rs:

• Demonstrates SQLx testing patterns
• Tests eql_v2.add_column() function
• Shows assertion patterns, setup/teardown
• Async/await patterns

Key Insights from Documentation

SQLx/Rust Approach

Pros:

• Type-safe database access
• Modern async/await patterns
• Good IDE support
• Connection pooling

Cons:

• Slow compile times (30s+ for test changes)
• Overkill for testing SQL functions
• Type system doesn't help much (SQL is dynamic)
• Smaller PostgreSQL testing ecosystem

pgTAP Approach

Pros:

• SQL-native, no impedance mismatch
• Tests run IN the database
• Designed specifically for PostgreSQL extensions
• Fast feedback loop (no compilation)
• Industry standard (used by PostgreSQL core)

Cons:

• Less familiar to Rust developers
• SQL-based testing may be unfamiliar

Comparison to PR #135

PR #135 implements pgTAP testing with:

• 91 pgTAP tests (structure + functionality)
• Docker integration
• Test runner scripts

This PR proposes SQLx/Rust with:

• Rust test infrastructure
• 1 example test showing patterns
• Comprehensive framework comparison documentation

Files Changed

Added:

• SQLX_TESTING_APPROACH.md - Rationale and architecture
• TESTING_FRAMEWORK_COMPARISON.md - Comprehensive framework analysis
• rust-tests/ - Complete Rust testing infrastructure
  • Cargo.toml, README.md, run-tests.sh
  • Example test: add_column_test.rs

Removed (from pgTAP PR):

• tasks/test-pgtap.sh
• tests/Dockerfile.pgtap
• tests/install_pgtap.sql
• tests/pgtap/ directory

Purpose of This PR

This is an experimental/evaluation branch meant to:

1. Document the SQLx testing approach
2. Provide comprehensive framework comparison
3. Enable informed decision-making
4. Show working SQLx test examples

Recommendation

The documentation in this PR suggests pgTAP may be the better choice for EQL because:

• It's SQL-native (matches the domain)
• Faster feedback loop
• Industry standard for PostgreSQL extensions
• No compilation overhead

However, SQLx could be valuable if:

• Team is primarily Rust-focused
• Need integration with other Rust tooling
• Want type-safe query building

Next Steps

Review the documentation and example code, then decide:

1. Adopt pgTAP approach (PR Add pgTAP testing infrastructure #135)
2. Adopt SQLx approach (this PR)
3. Hybrid: Use both for different test types
4. Continue with current bash-based testing

Related

• PR Add pgTAP testing infrastructure #135: pgTAP testing infrastructure (alternative approach)
• Previous attempt: Rust component system (too complex)