Jest Integration test failures produce a cryptic error stack trace

[mshustov]

I'm working on removing the legacy elasticsearch client and likely some test integration tests failures have been caused by my changes, but the error stack trace doesn't help me to debug the problem:

11:40:03   FAIL  packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts
11:40:03    ● Test suite failed to run
11:40:03  
11:40:03      /dev/shm/workspace/parallel/3/kibana/packages/kbn-optimizer/src/integration_tests/basic_optimization.test.ts: Error: No substitution given for "$0". If this is not meant to be a
11:40:03                  placeholder you may want to consider passing one of the following options to @babel/template:
11:40:03                  - { placeholderPattern: false, placeholderWhitelist: new Set(['$0'])}
11:40:03                  - { placeholderPattern: /^$0$/ }
11:40:03  
11:40:03                    placeholder you may want to consider passing one of the following options to @babel/template:
11:40:03                    - { placeholderPattern: false, placeholderWhitelist: new Set(['$0'])}
11:40:03                    - { placeholderPattern: /^$0$/ }
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined
11:40:03            at undefined

see #107619 for details.

It looks like a problem with the building pipeline. I didn't manage to find other failures on CI with the problem. See the last integration test failure on CI a few days ago https://kibana-ci.elastic.co/job/elastic+kibana+7.x/16019/execution/node/426/log/

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[mshustov]

I can reproduce failures on #107619 branch for src/core/server/http/integration_tests/core_services.test.ts file only. It fails with .sourceMap is an alias for .sourceMaps, cannot use both.
The error disappear if I remove import { MockElasticsearchClient } from './core_service.test.mocks'; statement from src/core/server/http/integration_tests/core_services.test.ts