vitest >=5.0.0 renamed `experimental_parseSpecifications` to `parseSpecifications`. Silent: code written for older versions still runs, without an error.

const fs = require("fs");
const path = require("path");
const cp = require("child_process");
const dir = "/w/parsespecs";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
fs.writeFileSync(path.join(dir, "math.test.mjs"), [
  "import { describe, test } from 'vitest'",
  "describe('math', () => {",
  "  test('adds', () => {})",
  "})",
].join("\n") + "\n");
fs.writeFileSync(path.join(dir, "run.mjs"), [
  "import { createVitest } from '/w/node_modules/vitest/dist/node.js'",
  "const dir = '/w/parsespecs'",
  "const vitest = await createVitest('test', { root: dir, config: false, watch: false })",
  "const names = async (method) => {",
  "  const spec = vitest.getRootProject().createSpecification(dir + '/math.test.mjs')",
  "  const modules = await vitest[method]([spec])",
  "  return [...modules[0].children.allTests()].map(t => t.fullName)",
  "}",
  "const result = { oldName: null, newType: typeof vitest.parseSpecifications, newName: null }",
  "try { result.oldName = await names('experimental_parseSpecifications') } catch (e) { result.oldError = String(e) }",
  "if (result.newType === 'function') {",
  "  try { result.newName = await names('parseSpecifications') } catch (e) { result.newError = String(e) }",
  "}",
  "await vitest.close()",
  "console.log('RESULT ' + JSON.stringify(result))",
  "process.exit(0)",
].join("\n") + "\n");
const r = cp.spawnSync(process.execPath, [path.join(dir, "run.mjs")], {
  cwd: dir,
  encoding: "utf8",
  env: { ...process.env, NO_COLOR: "1", CI: "1" },
  timeout: 60000,
});
const out = (r.stdout || "") + (r.stderr || "") + (r.error ? String(r.error) : "");
console.log(out);
const line = out.split("\n").find(l => l.startsWith("RESULT "));
if (!line) {
  console.error("ERROR: script printed no result (exit " + r.status + ")");
  process.exit(2);
}
const res = JSON.parse(line.slice(7));
const expected = JSON.stringify(["math > adds"]);
if (JSON.stringify(res.oldName) !== expected) {
  console.error("ERROR: experimental_parseSpecifications did not collect math > adds: " + JSON.stringify(res));
  process.exit(2);
}
if (res.newType === "undefined") {
  console.error("FAIL: vitest.parseSpecifications is undefined; only experimental_parseSpecifications exists");
  process.exit(1);
}
if (JSON.stringify(res.newName) === expected) {
  console.log("PASS: parseSpecifications and experimental_parseSpecifications both collect math > adds");
  process.exit(0);
}
console.error("ERROR: unexpected result " + JSON.stringify(res));
process.exit(2);

const fs = require("fs");
const path = require("path");
const cp = require("child_process");
const dir = "/w/parsespecs";
fs.rmSync(dir, { recursive: true, force: true });
fs.mkdirSync(dir, { recursive: true });
fs.writeFileSync(path.join(dir, "math.test.mjs"), [
  "import { describe, test } from 'vitest'",
  "describe('math', () => {",
  "  test('adds', () => {})",
  "})",
].join("\n") + "\n");
fs.writeFileSync(path.join(dir, "run.mjs"), [
  "import { createVitest } from '/w/node_modules/vitest/dist/node.js'",
  "const dir = '/w/parsespecs'",
  "const vitest = await createVitest('test', { root: dir, config: false, watch: false })",
  "const names = async (method) => {",
  "  const spec = vitest.getRootProject().createSpecification(dir + '/math.test.mjs')",
  "  const modules = await vitest[method]([spec])",
  "  return [...modules[0].children.allTests()].map(t => t.fullName)",
  "}",
  "const result = { oldName: null, newType: typeof vitest.parseSpecifications, newName: null }",
  "try { result.oldName = await names('experimental_parseSpecifications') } catch (e) { result.oldError = String(e) }",
  "if (result.newType === 'function') {",
  "  try { result.newName = await names('parseSpecifications') } catch (e) { result.newError = String(e) }",
  "}",
  "await vitest.close()",
  "console.log('RESULT ' + JSON.stringify(result))",
  "process.exit(0)",
].join("\n") + "\n");
const r = cp.spawnSync(process.execPath, [path.join(dir, "run.mjs")], {
  cwd: dir,
  encoding: "utf8",
  env: { ...process.env, NO_COLOR: "1", CI: "1" },
  timeout: 60000,
});
const out = (r.stdout || "") + (r.stderr || "") + (r.error ? String(r.error) : "");
console.log(out);
const line = out.split("\n").find(l => l.startsWith("RESULT "));
if (!line) {
  console.error("ERROR: script printed no result (exit " + r.status + ")");
  process.exit(2);
}
const res = JSON.parse(line.slice(7));
const expected = JSON.stringify(["math > adds"]);
if (JSON.stringify(res.oldName) !== expected) {
  console.error("ERROR: experimental_parseSpecifications did not collect math > adds: " + JSON.stringify(res));
  process.exit(2);
}
if (res.newType === "undefined") {
  console.error("FAIL: vitest.parseSpecifications is undefined; only experimental_parseSpecifications exists");
  process.exit(1);
}
if (JSON.stringify(res.newName) === expected) {
  console.log("PASS: parseSpecifications and experimental_parseSpecifications both collect math > adds");
  process.exit(0);
}
console.error("ERROR: unexpected result " + JSON.stringify(res));
process.exit(2);