Update test framework: fix run_tests.py to support all test files, add auto-import-check for test files

node_modules/import-in-the-middle/test/fixtures/import-after.mjs

@@ -0,0 +1,16 @@
+import { strictEqual } from 'assert'
+import { sep } from 'path'
+import * as os from 'node:os'
+import { Hook } from '../../index.js'
+
+const hooked = []
+
+Hook((_, name) => {
+  hooked.push(name)
+})
+
+strictEqual(hooked.length, 2)
+strictEqual(hooked[0], 'path')
+strictEqual(hooked[1], 'os')
+strictEqual(sep, '@')
+strictEqual(os.arch(), 'new_crazy_arch')