Jest tests fail when TypeScrip tsconfig baseUrl set to '.' and the project is nested in a src directory. moduleNameMapper error.

[pbeshai]

Describe the bug

When a project is nested somewhere in a directory named src, and the baseUrl in tsconfig.json is set to ".", all tests will fail with the following error:

 FAIL  src/App.test.tsx
  ● Test suite failed to run

    Configuration error:

    Could not locate module /Users/pbeshai/Workspace/bug-report/src/nested-src-bug-ts/node_modules/babel-preset-react-app/node_modules/@babel/runtime/helpers/interopRequireDefault mapped as:
    /Users/pbeshai/Workspace/bug-report/src/nested-src-bug-ts/src/nested-src-bug-ts/node_modules/babel-preset-react-app/node_modules/@babel/runtime/helpers/interopRequireDefault.

    Please check your configuration for these entries:
    {
      "moduleNameMapper": {
        "/src\/(.*)$/": "/Users/pbeshai/Workspace/bug-report/src/nested-src-bug-ts/src/$1"
      },
      "resolver": null
    }

After some investigation, I believe this is because the moduleNameMapper is not prefixed with ^ and so it matches the src earlier in the path.

Steps to reproduce

(Write your steps here:)

1. npx create-react-app my-app --typescript
2. Add baseUrl: "." to tsconfig.json
3. yarn test

Reproducible demo

https://github.com/pbeshai/cra-nested-src-bug-ts

Proposed Solution

In #7755 baseUrl was allowed to be set to .. If we modify ... I now see this is already fixed in #7818 and #7822.

I'll post and close this just in case someone else is stumbling on this problem and couldn't find any results.