ts-jest fails to run a tsx test file because of "Import" from a module's js file
The problem is that Jest is not transforming that file. And in plain JS, import is not valid. You need to configure Jest so it will transform that file.
First, change the transform to also process files with extensions js or jsx (in addition to ts files:)
"jest": { "transform": { "^.+\\.(ts|js)x?$": "ts-jest" },Next you need to whitelist the directory, so Jest does transform it. This skips transforming all files in node_modules except the quill-mention dir.
"transformIgnorePatterns": [ "<rootDir>/node_modules/(?!(quill-mention)/)" ]This should get past the problems with quill-mention. And it should now fail with ReferenceError: MutationObserver is not defined, which is a different issue, having to do with Jest's JSDom environment it uses. You can read about how to fix that here:
Testing MutationObserver with Jest
You may also want to consider moving to babel-jest + @babel/preset-typescript instead of using ts-jest.