[PM-2328] Fix jest deprecations (#5483)

libs/shared/jest.config.ts.js

@@ -0,0 +1,29 @@
+/* eslint-env node */
+
+/** @type {import('jest').Config} */
+module.exports = {
+  testMatch: ["**/+(*.)+(spec).+(ts)"],
+
+  // Workaround for a memory leak that crashes tests in CI:
+  // https://github.com/facebook/jest/issues/9430#issuecomment-1149882002
+  // Also anecdotally improves performance when run locally
+  maxWorkers: 3,
+
+  transform: {
+    "^.+\\.tsx?$": [
+      "ts-jest",
+      {
+        // Jest does not use tsconfig.spec.json by default
+        tsconfig: "<rootDir>/tsconfig.spec.json",
+        // Further workaround for memory leak, recommended here:
+        // https://github.com/kulshekhar/ts-jest/issues/1967#issuecomment-697494014
+        // Makes tests run faster and reduces size/rate of leak, but loses typechecking on test code
+        // See https://bitwarden.atlassian.net/browse/EC-497 for more info
+        isolatedModules: true,
+        astTransformers: {
+          before: ["<rootDir>/../../libs/shared/es2020-transformer.ts"],
+        },
+      },
+    ],
+  },
+};