ci: Fix a couple of memory leaks in test setups

This fixes 2 memory leaks in our test setup:

1. Jest passes every file through transform and caches the results
on disk and in memory. That included every generated client as well, so
they were kept in memory from the time they were first loaded until
process finishes, even though they are needed only for 1 test suite.
Fixed by using `transformIgnorePatterns` options in jest config.

2. `debug` library keeps a list of last 100 logs that would be used for
panic error messages later. If error object gets into this list, it will
keep whole jest sandbox alive until process finishes. Fixed by clearing
logs on `$disconnect`

Fix #16594

packages/client/src/runtime/getPrismaClient.ts

@@ -1,5 +1,5 @@
 import { Context, context } from '@opentelemetry/api'
-import Debug from '@prisma/debug'
+import Debug, { clearLogs } from '@prisma/debug'
 import {
   BatchTransactionOptions,
   BinaryEngine,
@@ -591,6 +591,11 @@ export function getPrismaClient(config: GetPrismaClientConfig) {
         e.clientVersion = this._clientVersion
         throw e
       } finally {
+        // Debug module keeps a list of last 100 logs regardless of environment variables.
+        // This can cause a memory leak. It's especially bad in jest environment where keeping an
+        // error in this list will prevent jest sandbox from being GCed. Clearing logs on disconnect
+        // helps to avoid that
+        clearLogs()
         if (!this._dataProxy) {
           this._dmmf = undefined
         }

packages/client/tests/functional/jest.config.js

@@ -1,10 +1,21 @@
 'use strict'
 const os = require('os')
+const path = require('path')
+
+const runtimeDir = path.dirname(require.resolve('../../runtime'))
+const packagesDir = path.resolve('..', '..', '..')
 
 module.exports = () => {
   const configCommon = {
     testMatch: ['**/*.ts', '!(**/*.d.ts)', '!(**/_utils/**)', '!(**/_*.ts)', '!(**/.generated/**)'],
-    transformIgnorePatterns: [],
+    // By default, jest passes every file it loads thorough a transform and caches result both on disk and in memory
+    // That includes all generated clients as well. So, unless we ignore them, they'd be kept in memory until test process
+    // is finished, even though they are needed for 1 test only
+    transformIgnorePatterns: [
+      '[\\/]node_modules[\\/]',
+      escapeRegex(runtimeDir),
+      `${escapeRegex(packagesDir)}[\\/][^\\/]+[\\/]dist[\\/]`,
+    ],
     reporters: [
       'default',
       [
@@ -47,3 +58,12 @@ module.exports = () => {
     },
   }
 }
+
+/**
+ * https://stackoverflow.com/a/6969486
+ * @param {string} str
+ * @returns {string}
+ */
+function escapeRegex(str) {
+  return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
+}

packages/debug/src/index.ts

@@ -81,5 +81,9 @@ export function getLogs(numChars = 7500): string {
   return output.slice(-numChars)
 }
 
+export function clearLogs() {
+  debugArgsHistory.length = 0
+}
+
 export { Debug }
 export default Debug