Tests are running much slower in 7.0.0-alpha.1 with --no-cache

My setup: babel-preset-env: 1.7.0, jest: 23.6.0, jest-preset-angular: 7.0.0-alpha.1, jest-sonar-reporter: 2.0.0,

I am using babel-jest to process *.js files.

I am trying to upgrade from 6.0.0 -> 7.0.0-alpha.1. I am running jest with: npm run jest -- --no-cache and observing that the time required to finish tests goes up from ~120s to around 950s. When i enable the cache, then the first run is slow, but consecutive run is much faster (same as in version 6.0.0) - around 30s.

Anyone else experiencing same behavior? What could be the cause for this, where should i look?

[ahnpnl]

FYI, this might be one of the causes of performance

[Ludevik]

@wtho @thymikee thanks. I have tested with alpha.2 and it is a bit faster. I’m currently at ~500s with --no-cache and 300s on the first run after --clearCache. I’ve put log into create visitor function and it is called multiple times for some .ts files, it depends on the situation. Jest spawns 7 threads on my machine to run the tests and each of that thread transforms .ts and .js files on its own, so some of the files are transformed multiple times, up to 7 times. I understand now why each of my file in library is transformed 7 times when i change the mapping from dist to src. It is because when i tell jest to use dist folder it doesn’t need to transform my library as it is already compiled to .js. When i ran my tests with src then i got 7 hits in createVisitor for my library’s index.ts files which in turn transforms 7 times every exported library file.

I will write a question to ts-jest directly as jest-preset-angular just uses that and it seems that the astTransformer is quite fast.