Testing Skill

Write TypeScript runtime and type tests for this project.

Imports

import * as test from "bun:test"
import * as type from "expect-type"

Test Structure

Use test.it for individual tests and test.describe for grouping:

test.describe("MyModule", () => {
  test.it("should do something", () => {
    // test body
  })
})

Never use test.test - always use test.it.

Assertion Formatting

Put each method call on a new line with 2-space indentation:

test
  .expect(value)
  .toBe(expected)

test
  .expect(result)
  .toEqual({ foo: "bar" })

test
  .expect(() => riskyOperation())
  .toThrow("error message")

No blank lines between consecutive assertions:

test
  .expect(a)
  .toBe(1)
test
  .expect(b)
  .toBe(2)
test
  .expect(c)
  .toBe(3)

Type Assertions with expect-type

Use expect-type for compile-time type checking. Inline types directly - no type aliases:

// Check a value matches a type
type
  .expectTypeOf(someValue)
  .toMatchTypeOf<ExpectedType>()

// Check two types are exactly equal
type
  .expectTypeOf<ActualType>()
  .toEqualTypeOf<ExpectedType>()

// Check a type extends another
type
  .expectTypeOf<SubType>()
  .toExtend<SuperType>()

Naming Conventions

Avoid variable names that shadow imports. Use descriptive suffixes:

// Bad - shadows `test` import
const test = Commander.make({ name: "test" })

// Good
const testCmd = Commander.make({ name: "test" })

File Location

Co-locate tests with source files: Module.test.ts alongside Module.ts