Migrate Rust installation to bash with comprehensive testing

[ooloth]

💪 What

• Files Created:
  • lib/rust-utils.bash - Rust utility functions (3 functions, 4 tests)
  • bin/install/rust.bash - Bash replacement for rust.zsh
  • test/install/test-rust-utils.bats - 4 utility function tests
  • test/install/test-rust-installation.bats - 3 integration tests
• Test Coverage: 7 comprehensive tests covering all functionality
• Quality: 7/7 tests passing, zero shellcheck warnings

🤔 Why

• Bash Migration: Continues migration from custom zsh to industry-standard bash + shellcheck + bats
• Professional Tooling: Enables shellcheck linting and bats testing for Rust installation
• Shared Utilities: Extracts reusable Rust logic for future use in update scripts
• Better Error Handling: Uses bash strict mode and structured error handling

👀 Usage

Run Rust installation:

./bin/install/rust.bash

Features:

• Detects existing Rust installation (skips if present)
• Sets custom CARGO_HOME and RUSTUP_HOME paths
• Downloads and runs rustup installer
• Uses proper security flags for curl download

👩‍🔬 How to validate

Run utility tests:

bats test/install/test-rust-utils.bats

Run integration tests:

bats test/install/test-rust-installation.bats

Expected output (7 tests total):

# Utility tests
1..4
ok 1 rust_installed returns false when rustup not found
ok 2 rust_installed returns true when rustup is found
ok 3 setup_rust_environment sets CARGO_HOME and RUSTUP_HOME
ok 4 install_rust_toolchain uses curl to download rustup installer

# Integration tests
1..3
ok 1 rust.bash exists and is executable
ok 2 rust.bash skips installation when rust is already installed
ok 3 rust.bash installs rust when not present

Verify shellcheck compliance:

shellcheck lib/rust-utils.bash bin/install/rust.bash

Test manually:

# Test with existing rust (if you have it)
./bin/install/rust.bash  # Should skip

# Test in clean environment
export PATH="/usr/bin:/bin"  # Remove rust from PATH
./bin/install/rust.bash     # Should install

Architecture

Three-Tier Pattern:

1. Core Utilities (lib/rust-utils.bash): Pure logic, shellcheck compliant, fully tested
2. Installation Script (bin/install/rust.bash): Orchestrates utilities, professional tooling
3. Future Interactive Tools: Will use shared utilities for rich user experience

Functions Provided:

• rust_installed() - Detects rustup command availability
• setup_rust_environment() - Sets CARGO_HOME and RUSTUP_HOME
• install_rust_toolchain() - Downloads and runs rustup installer

🔗 Related links

• Bash Migration Epic - Overall strategy
• Original rust.zsh - Implementation comparison
• Setup.bash Integration - Will integrate this script
• Rust Installation Guide - Official rustup documentation

Implementation Details

TDD Approach:

• 7 test cases following strict TDD: red → green → refactor → commit
• Comprehensive mocking for isolated testing
• Both unit tests (utilities) and integration tests (full script)
• Behavioral testing focus - tests what code does, not how

Key Features:

• Detection Logic: Uses command -v rustup for reliable detection
• Custom Paths: Sets .config/cargo and .config/rustup instead of defaults
• Security: Uses proper TLS and protocol restrictions for curl
• Error Handling: Strict mode + graceful failure handling
• Modularity: Shared utilities enable code reuse

Migration Benefits:

• Better Development Tools: shellcheck + bats instead of custom zsh framework
• Industry Standards: Follows bash best practices and conventions
• Easier Maintenance: Standard testing and linting tools
• Code Sharing: Utilities can be reused in update scripts