test: Fix Jest memory issues

jest.config.js

@@ -1,4 +1,38 @@
+const os = require('os');
+const v8 = require('v8');
+
+// Several parts inspired by https://github.com/renovatebot/renovate/blob/main/package.json
+
+const ci = !!process.env.CI;
+
+const cpus = os.cpus();
+const mem = os.totalmem();
+const stats = v8.getHeapStatistics();
+
+if (ci) {
+  process.stderr.write(`Host stats:
+  Cpus:      ${cpus.length}
+  Memory:    ${(mem / 1024 / 1024 / 1024).toFixed(2)} GB
+  HeapLimit: ${(stats.heap_size_limit / 1024 / 1024 / 1024).toFixed(2)} GB
+`);
+}
+
+// See also https://github.com/jestjs/jest/issues/11956
+function jestGithubRunnerSpecs() {
+  return {
+    maxWorkers: cpus.length,
+    workerIdleMemoryLimit: '1500MB',
+  };
+}
+
 module.exports = {
+  transform: {
+    '^.+\\.ts$': [ 'ts-jest', {
+        tsconfig: '<rootDir>/tsconfig.json',
+        diagnostics: false,
+        isolatedModules: true,
+    }],
+  },
   testRegex: '/test/(unit|integration)/.*\\.test\\.ts$',
   moduleFileExtensions: [
     'ts',
@@ -13,5 +47,7 @@ module.exports = {
   },
   // Slower machines had problems calling the WebSocket integration callbacks on time
   testTimeout: 60000,
-  preset: 'ts-jest',
+
+  reporters: ci ? ['default', 'github-actions'] : ['default'],
+  ...(ci && jestGithubRunnerSpecs()),
 };

package.json

@@ -68,7 +68,7 @@
     "test": "npm run test:ts && npm run jest",
     "test:deploy": "test/deploy/validate-configs.sh",
     "test:ts": "tsc -p test --noEmit",
-    "test:integration": "node --expose-gc --no-compilation-cache ./node_modules/jest/bin/jest.js -- test/integration",
+    "test:integration": "jest test/integration",
     "test:unit": "jest --config=./jest.coverage.config.js test/unit",
     "test:watch": "jest --coverageReporters none --watch test/unit",
     "validate": "componentsjs-compile-config urn:solid-server:default:Initializer -c config/default.json -f > /dev/null",