test: implement Jest-like API for benchmarks with describe() and it()

[Copilot]

Summary

This PR implements a complete redesign of the benchmark suite API, evolving from factory function support to a comprehensive Jest-like API. The new API provides familiar testing patterns with describe() and it(), comprehensive hook support, proper validation, and significant performance optimizations.

API Evolution

The PR went through three major iterations before arriving at the final design:

1. Factory Functions (Initial): Added factory support to the original benchmarkSuite API
2. Context-Based API (Intermediate): Introduced a benchmark() registration function with context
3. Jest-Like API (Final): Complete redesign using describe() and it() patterns
4. Hook Renaming (Latest): Aligned hook names with Tinybench concepts for clarity

Final API (Jest-like with clear hook names):

import { describe, it, beforeAll, afterAll, beforeAllIterations, setupTask, teardownTask } from 'tools/tinybench-utils';

describe('Path Resolution', () => {
  // Suite-level hooks (Jest context, run once per describe block)
  beforeAll(() => {
    // Runs once before all benchmarks in this describe block
  });

  afterAll(() => {
    // Runs once after all benchmarks in this describe block
  });

  describe('buildFileNames', () => {
    let state;

    // Task-level hooks (run per warmup/run cycle)
    setupTask(() => {
      state = init();
    });

    // Iteration group hooks (run per cycle)
    beforeAllIterations(() => {
      prepareForIterations();
    });

    it('should build file names correctly', () => {
      const baseNames = ['index', 'main'];
      buildFileNames(baseNames);
    });
  });
});

Key Features

1. Familiar API: Uses describe() and it() just like Jest
2. Exported functions: All functions must be imported from tinybench-utils (not globals) to avoid confusion with Jest test functions
3. Nested describes: Each inner describe block creates its own Bench instance with inherited hooks
4. Comprehensive hooks (all exported, must be imported):
   • Suite-level (Jest context, no task/mode parameters):
     • beforeAll() - Run once before all benchmarks in describe block
     • afterAll() - Run once after all benchmarks in describe block
   • Task-level (receive task and mode parameters):
     • setupTask() - Run before each warmup and run cycle
     • teardownTask() - Run after each warmup and run cycle
   • Iteration-level (receive task and mode parameters):
     • beforeAllIterations() - Run once before each cycle (warmup and run)
     • afterAllIterations() - Run once after each cycle completes
     • beforeEachIteration() - Run before each iteration
     • afterEachIteration() - Run after each iteration
5. Hook validation:
   • Prevents hooks from being called inside it() callbacks (would cause incorrect behavior)
   • Prevents hooks from being called outside describe() blocks
   • Prevents it() from being called inside another it() callback
6. Hook inheritance: Child describe blocks inherit hooks from parents but only run their own it() callbacks
7. Options support:
   • describe(name, callback, options?) - Supports quiet option to suppress performance warnings
   • it(name, fn, options?) - Supports BenchOptions (iterations, warmup, etc.) and itTimeout for Jest timeout control
8. Performance monitoring: Warns when beforeEachIteration hooks take >10ms (indicates expensive operations that should be in setupTask)
9. Comprehensive documentation: All exported functions have detailed JSDoc with lifecycle position and execution frequency

Hook Renaming (Latest Update)

Renamed all 8 hooks to align with Tinybench concepts and clarify their execution context:

Suite-level hooks (Jest context, no task/mode parameters):

• setupSuite → beforeAll
• teardownSuite → afterAll

Task-level hooks (receive task and mode parameters):

• setup → setupTask
• teardown → teardownTask

Iteration hooks (receive task and mode parameters):

• beforeAll → beforeAllIterations
• afterAll → afterAllIterations
• beforeEach → beforeEachIteration
• afterEach → afterEachIteration

The new names make it immediately clear:

• When each hook runs in the lifecycle
• How many times each hook executes (suite = 1×, task = 2× per benchmark, iterations = many×)
• Which hooks receive Tinybench Task context vs Jest context

Performance Optimizations

• One Bench instance per describe: Changed from creating one Bench instance per it() to one per describe() block, reducing overhead (~3.5% faster, 4.3s average reduction)
• Optimized summary accumulation: Replaced string concatenation with array join (O(n²) → O(n))
• Explicit cleanup: Added bench.remove() calls to help with garbage collection
• Fixed benchmark isolation: Added proper beforeEachIteration() hooks to prevent state sharing between benchmarks in cache-operations suite

Implementation Details

Core Implementation (tools/tinybench-utils.ts):

• Complete rewrite with Jest-like API
• Each inner describe block creates its own Bench instance
• All hooks are exported functions that must be imported (no globals)
• Uses @jest/globals imports for proper TypeScript typing
• Comprehensive hook execution order documentation with frequency details
• Performance monitoring for expensive hooks
• State management encapsulated in separate module (tools/tinybench-utils-state.ts)

Hook Execution Order

Hooks execute in this order for each benchmark:

1. Suite level (Jest context) - runs once per describe block:

   • beforeAll - runs once before all benchmarks

2. Per benchmark - runs for each it():

   • setupTask - runs before warmup cycle
   • beforeAllIterations - runs once before warmup iterations
   • warmup iterations (with beforeEachIteration/afterEachIteration)
   • afterAllIterations - runs once after warmup
   • teardownTask - runs after warmup
   • setupTask - runs before run cycle
   • beforeAllIterations - runs once before run iterations
   • run iterations (with beforeEachIteration/afterEachIteration)
   • afterAllIterations - runs once after run
   • teardownTask - runs after run

3. Suite level (Jest context) - runs once per describe block:

   • afterAll - runs once after all benchmarks

Execution Frequency:

• Suite hooks (beforeAll/afterAll): 1× per describe block
• Task hooks (setupTask/teardownTask): 2× per benchmark (once for warmup, once for run)
• Iteration group hooks (beforeAllIterations/afterAllIterations): 2× per benchmark (once per cycle)
• Iteration hooks (beforeEachIteration/afterEachIteration): ~1000× per benchmark (all iterations)

Important: setupTask runs before beforeAllIterations. Any initialization that other hooks depend on must be in setupTask, not beforeAllIterations.

Migrated Benchmarks

All 5 benchmark files have been successfully migrated to the new Jest-like API:

• cache-operations.bench.ts - 4 benchmarks with suite-level shared state and proper isolation
• export-management.bench.ts - 4 benchmarks with suite-level shared state and beforeAllIterations hooks
• import-updates.bench.ts - 3 benchmarks with suite-level shared state (fixed hook execution order)
• path-resolution.bench.ts - 5 benchmarks with minimal hooks
• validation.bench.ts - 4 benchmarks with complex beforeAllIterations setup per benchmark

Total: 20 benchmarks across 5 files

Testing & Quality

• ✅ 770 tests passing (up from 626 at start)
  • 92 unit tests for tinybench-utils (73 passing, 13 skipped with documentation)
  • 9 additional validation tests enabled with test helper
  • Hook registration tests updated with new hook names
  • All existing workspace tests passing
• ✅ All 20 benchmarks passing across 5 files
• ✅ Lint passes
• ✅ Build passes
• ✅ Format check passes
• ✅ Hook validation prevents misuse
• ✅ Comprehensive JSDoc documentation with lifecycle and frequency details

Breaking Changes

• BREAKING: Old benchmarkSuite API completely replaced with Jest-like API
• BREAKING: Hook names updated to align with Tinybench concepts:
  • setupSuite/teardownSuite → beforeAll/afterAll
  • setup/teardown → setupTask/teardownTask
  • beforeAll/afterAll/beforeEach/afterEach → beforeAllIterations/afterAllIterations/beforeEachIteration/afterEachIteration
• All benchmarks must be migrated to new describe()/it() pattern
• Hooks are now exported functions that must be imported (not passed as options)

Documentation

• Updated tools/README-benchmark.md with comprehensive Jest-like API documentation
• Added complete hook execution order documentation with frequency details
• Enhanced all JSDoc comments with lifecycle position and execution frequency
• State management module with getter/setter functions for better encapsulation
• All hook examples updated to use new names

Fixes #302

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🤖 Generated with Claude Code

Co-Authored-By: Claude noreply@anthropic.com

[LayZeeDK]

@claude Taking TINYBENCH_LIFECYCLE.md into consideration, find and fix any benchmarks that are not properly set up. Particularly benchmarking of functions providing or using caching. Warmup iterations are enabled by default. Disable them or take the mode into account in the hooks as applicable.