vitest.config.ts

// CHANGE: Migrate from Jest to Vitest with mathematical equivalence
// WHY: Faster execution, native ESM, Effect integration via @effect/vitest
// QUOTE(ТЗ): "Проект использует Effect + функциональную парадигму"
// REF: Migration from jest.config.mjs
// PURITY: SHELL (configuration only)
// INVARIANT: ∀ test: behavior_jest ≡ behavior_vitest
// EFFECT: Effect<TestReport, never, TestEnvironment>
// COMPLEXITY: O(n) test execution where n = |test_files|

import { defineConfig } from "vitest/config";
import tsconfigPaths from "vite-tsconfig-paths";

export default defineConfig({
	plugins: [tsconfigPaths()], // Resolves @/* paths from tsconfig
	test: {
		// CHANGE: Native ESM support without experimental flags
		// WHY: Vitest designed for ESM, no need for --experimental-vm-modules
		// INVARIANT: Deterministic test execution without side effects
		globals: false, // IMPORTANT: Use explicit imports for type safety
		environment: "node",

		// CHANGE: Match Jest's test file patterns
		// INVARIANT: Same test discovery as Jest
		include: ["test/**/*.{test,spec}.ts"],
		exclude: ["node_modules", "dist", "dist-test"],

		// CHANGE: Coverage with 100% threshold for CORE (same as Jest)
		// WHY: CORE must maintain mathematical guarantees via complete coverage
		// INVARIANT: coverage_vitest ≥ coverage_jest ∧ ∀ f ∈ CORE: coverage(f) = 100%
		coverage: {
			provider: "v8", // Faster than babel (istanbul), native V8 coverage
			reporter: ["text", "json", "html"],
			include: ["src/**/*.ts"],
			exclude: [
				"src/**/*.test.ts",
				"src/**/*.spec.ts",
				"src/**/__tests__/**",
				"scripts/**/*.ts",
			],
			// CHANGE: Maintain exact same thresholds as Jest
			// WHY: Enforce 100% coverage for CORE, 10% minimum for SHELL
			// INVARIANT: ∀ f ∈ src/core/**/*.ts: all_metrics(f) = 100%
			// NOTE: Vitest v8 provider collects coverage for all matched files by default
			thresholds: {
				"src/core/**/*.ts": {
					branches: 100,
					functions: 100,
					lines: 100,
					statements: 100,
				},
				global: {
					branches: 10,
					functions: 10,
					lines: 10,
					statements: 10,
				},
			},
		},

		// CHANGE: Faster test execution via thread pooling
		// WHY: Vitest uses worker threads by default (faster than Jest's processes)
		// COMPLEXITY: O(n/k) where n = tests, k = worker_count
		// NOTE: Vitest runs tests in parallel by default, no additional config needed

		// CHANGE: Clear mocks between tests (Jest equivalence)
		// WHY: Prevent test contamination, ensure test independence
		// INVARIANT: ∀ test_i, test_j: independent(test_i, test_j) ⇒ no_shared_state
		clearMocks: true,
		mockReset: true,
		restoreMocks: true,

		// CHANGE: Disable globals to enforce explicit imports
		// WHY: Type safety, explicit dependencies, functional purity
		// NOTE: Tests must import { describe, it, expect } from "vitest"
	},
	resolve: {
		alias: {
			"@": "/src",
		},
	},
});