[Ops] Add debug logging to certain jest error cases

packages/kbn-test/jest-preset.js

@@ -130,4 +130,7 @@ module.exports = {
   globals: {
     structuredClone: {},
   },
+
+  testResultsProcessor:
+    '<rootDir>/packages/kbn-test/src/jest/result_processors/logging_result_processor.js',
 };

packages/kbn-test/src/jest/result_processors/logging_result_processor.js

@@ -0,0 +1,36 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+const FAILURE_MESSAGE_TRIGGERS = ['but is not defined anymore'];
+const log = (...args) => {
+  const loggable = args.map((arg) =>
+    typeof arg === 'string' ? arg : JSON.stringify(arg, null, 2)
+  );
+  process.stdout.write(`${loggable.join(' ')}\n`, 'utf8');
+};
+/**
+ * This processor looks for specific errors, and logs the result context of test suites where they occur.
+ * @param results
+ * @returns {*}
+ */
+module.exports = (results) => {
+  const resultsThatMatchTriggers = results.testResults.filter(
+    (e) =>
+      e.failureMessage &&
+      FAILURE_MESSAGE_TRIGGERS.some((trigger) => e.failureMessage.includes(trigger))
+  );
+
+  if (resultsThatMatchTriggers.length !== 0) {
+    log('The following test suites failed, with notable errors:');
+    resultsThatMatchTriggers.forEach((e) => {
+      log(` -> ${e.testFilePath}`, 'Details: ', e, '\n');
+    });
+  }
+
+  return results;
+};