# BUPKIS

> A TypeScript assertion library using natural language function calls instead of chainable methods. Write `expect(value, 'to be a string')` instead of `expect(value).toBeString()`.

- Natural language phrases: `expect(user, 'to satisfy', { name: expect.it('to be a string') })`
- Automatic negation: `expect(42, 'not to be a string')`
- Concatenation: `expect(n, 'to be a number', 'and', 'to be greater than', 0)`
- Embeddable assertions: `expect.it()` for nested validation
- Custom assertions: `createAssertion(['to be even'], (n) => n % 2 === 0)`
- Uses Zod v4 for validation and type inference

## Docs
- [Basic Usage](https://bupkis.zip/documents/Basic_Usage/)
- [Creating Custom Assertions](https://bupkis.zip/documents/Creating_Custom_Assertions/)
- [Testing Custom Assertions](https://bupkis.zip/documents/Testing_Custom_Assertions/)

## Assertions
- [All Assertions](https://bupkis.zip/documents/All_Assertions/)
- [Collections Assertions](https://bupkis.zip/documents/Collections_Assertions/)
- [Date & Time Assertions](https://bupkis.zip/documents/Date___Time_Assertions/)
- [Equality & Comparison Assertions](https://bupkis.zip/documents/Equality___Comparison_Assertions/)
- [Error Assertions](https://bupkis.zip/documents/Error_Assertions/)
- [Function Assertions](https://bupkis.zip/documents/Function_Assertions/)
- [Iterable Assertions](https://bupkis.zip/documents/Iterable_Assertions/)
- [Numeric Assertions](https://bupkis.zip/documents/Numeric_Assertions/)
- [Object Assertions](https://bupkis.zip/documents/Object_Assertions/)
- [Other Assertions](https://bupkis.zip/documents/Other_Assertions/)
- [Primitive Assertions](https://bupkis.zip/documents/Primitive_Assertions/)
- [Promise Assertions](https://bupkis.zip/documents/Promise_Assertions/)
- [Snapshot Assertions](https://bupkis.zip/documents/Snapshot_Assertions/)
- [String & Pattern Assertions](https://bupkis.zip/documents/String___Pattern_Assertions/)

## Reference
- [About Assertions](https://bupkis.zip/documents/About_Assertions/)
- [Caveats & Errata](https://bupkis.zip/documents/Caveats___Errata/)
- [Glossary of Terms](https://bupkis.zip/documents/Glossary_of_Terms/)

## Release Notes
- [@bupkis/events](https://bupkis.zip/documents/_bupkis_events/)
- [@bupkis/from-chai](https://bupkis.zip/documents/_bupkis_from-chai/)
- [@bupkis/from-jest](https://bupkis.zip/documents/_bupkis_from-jest/)
- [@bupkis/http](https://bupkis.zip/documents/_bupkis_http/)
- [@bupkis/msw](https://bupkis.zip/documents/_bupkis_msw/)
- [@bupkis/property-testing](https://bupkis.zip/documents/_bupkis_property-testing/)
- [@bupkis/rxjs](https://bupkis.zip/documents/_bupkis_rxjs/)
- [@bupkis/sinon](https://bupkis.zip/documents/_bupkis_sinon/)
- [bupkis](https://bupkis.zip/documents/bupkis/)

## Plugins
- [@bupkis/events](https://bupkis.zip/documents/_bupkis_events-1/)
- [@bupkis/http](https://bupkis.zip/documents/_bupkis_http-1/)
- [@bupkis/msw](https://bupkis.zip/documents/_bupkis_msw-1/)
- [@bupkis/rxjs](https://bupkis.zip/documents/_bupkis_rxjs-1/)
- [@bupkis/sinon](https://bupkis.zip/documents/_bupkis_sinon-1/)

## Migration Tools
- [@bupkis/from-assert](https://bupkis.zip/documents/_bupkis_from-assert/)
- [@bupkis/from-chai](https://bupkis.zip/documents/_bupkis_from-chai-1/)
- [@bupkis/from-jest](https://bupkis.zip/documents/_bupkis_from-jest-1/)

## Testing Utilities
- [@bupkis/property-testing](https://bupkis.zip/documents/_bupkis_property-testing-1/)

## API
- [API Reference](https://bupkis.zip/modules/bupkis/): Full TypeScript API documentation
- [expect()](https://bupkis.zip/functions/bupkis.expect/): Main assertion function
- [expectAsync()](https://bupkis.zip/functions/bupkis.expectAsync/): Async assertion function
- [createAssertion()](https://bupkis.zip/functions/bupkis.createAssertion/): Create custom assertions
- [use()](https://bupkis.zip/functions/bupkis.use/): Register custom assertions

## Quick Reference

```javascript
// Type assertions
expect(value, 'to be a string');
expect(value, 'to be a number');
expect(value, 'to be an array');

// Equality
expect(actual, 'to equal', expected);
expect(obj, 'to deep equal', expected);
expect(obj, 'to satisfy', { name: 'Alice' });

// Negation
expect(42, 'not to be a string');

// Concatenation
expect(n, 'to be a number', 'and', 'to be greater than', 0);

// Embeddable assertions
expect(user, 'to satisfy', {
  name: expect.it('to be a string'),
  age: expect.it('to be greater than', 18)
});
```