test: convert tests to use vitest.

Author: Codex-

.eslintrc.json

@@ -7,7 +7,7 @@
   "ignorePatterns": [
     "lib/__fixtures__/**/*.ts",
     "esbuild.config.mjs",
-    "jest.config.ts",
+    "vite.config.ts",
     "coverage",
     "dist",
     "smoke-tests"

jest.config.ts

@@ -1,5 +1,6 @@
-import path from "path";
+import path from "node:path";
 import { cosmiconfig, cosmiconfigSync } from "cosmiconfig";
+import { describe, expect, it } from "vitest";
 import { TypeScriptLoader } from ".";
 
 describe("TypeScriptLoader", () => {
@@ -36,7 +37,7 @@ describe("TypeScriptLoader", () => {
 
       try {
         await cfg.load(path.resolve(fixturesPath, "invalid.fixture.ts"));
-        fail("Should fail to load invalid TS");
+        throw new Error("Should fail to load invalid TS");
       } catch (error: any) {
         expect(error?.name).toStrictEqual("TypeScriptCompileError");
       }

lib/index.spec.ts

@@ -1,13 +1,40 @@
-import fs from "fs";
-import path from "path";
+import fs from "node:fs";
+import path from "node:path";
 import { Loader } from "cosmiconfig";
+import {
+  afterAll,
+  afterEach,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  SpyInstance,
+  vi,
+} from "vitest";
+
+vi.mock("ts-node", async () => {
+  const tsnode = await vi.importActual<typeof import("ts-node")>("ts-node");
+
+  let writableTsNode: any = {};
+  Object.keys(tsnode).forEach((key) =>
+    Object.defineProperty(writableTsNode, key, {
+      value: (tsnode as any)[key],
+      writable: true,
+    })
+  );
+
+  return writableTsNode;
+});
+
 import * as tsnode from "ts-node";
+
 import { TypeScriptLoader } from "./loader";
 import { TypeScriptCompileError } from "./typescript-compile-error";
 
 describe("TypeScriptLoader", () => {
   const fixturesPath = path.resolve(__dirname, "__fixtures__");
-  const tsNodeSpy = jest.spyOn(tsnode, "register");
+  const tsNodeSpy = vi.spyOn(tsnode, "register");
 
   let loader: Loader;
 
@@ -19,6 +46,10 @@ describe("TypeScriptLoader", () => {
     loader = TypeScriptLoader();
   });
 
+  afterAll(() => {
+    vi.restoreAllMocks();
+  });
+
   it("should parse a valid TS file", () => {
     const filePath = path.resolve(fixturesPath, "valid.fixture.ts");
     loader(filePath, readFixtureContent(filePath));
@@ -40,7 +71,7 @@ describe("TypeScriptLoader", () => {
     try {
       const filePath = path.resolve(fixturesPath, "invalid.fixture.ts");
       loader(filePath, readFixtureContent(filePath));
-      fail(
+      throw new Error(
         "Error should be thrown upon failing to transpile an invalid TS file."
       );
     } catch (error: unknown) {
@@ -51,10 +82,10 @@ describe("TypeScriptLoader", () => {
   describe("ts-node", () => {
     const unknownError = "Test Error";
 
-    let stub: jest.SpyInstance<tsnode.Service, [service: tsnode.Service]>;
+    let stub: SpyInstance<[service: tsnode.Service], tsnode.Service>;
 
     beforeEach(() => {
-      stub = jest.spyOn(tsnode, "register").mockImplementation(
+      stub = vi.spyOn(tsnode, "register").mockImplementation(
         () =>
           ({
             compile: (): string => {
@@ -73,7 +104,7 @@ describe("TypeScriptLoader", () => {
     it("rethrows an error if it is not an instance of Error", () => {
       try {
         loader("filePath", "readFixtureContent(filePath)");
-        fail(
+        throw new Error(
           "Error should be thrown upon failing to transpile an invalid TS file."
         );
       } catch (error: unknown) {

lib/loader.spec.ts

@@ -1,3 +1,4 @@
+import { describe, expect, it } from "vitest";
 import { TypeScriptCompileError } from "./typescript-compile-error";
 
 describe("TypeScriptCompileError", () => {