Cypress causing type errors in jest assertions

Question

I ran into this problem yesterday. It seems that what you are saying is correct, cypress and jest both declares types for expect. In this case the cypress declaration seem to be the one that is picked up. Here’s an issue from the cypress repo regarding this:

https://github.com/cypress-io/cypress/issues/1603

The solution mentioned in there worked for me. You need to exclude the jest spec files from in tsconfig.json and then declare a tsconfig.spec.json where they are explicitly included again.

tsconfig.json:

{
  ...,
  "exclude": [
    "**/*.spec.ts"
  ]
}

tsconfig.spec.json:

{
  "extends": "./tsconfig.json",
  "include": [
    "**/*.spec.ts"
  ],
  ...
}

With this in place, both my (angular 8) app compiles fine and I can run the jest tests without issue. Here’s another example mentioned in the issue with a similar fix being implemented:

https://github.com/neiltownsley/react-typescript-cypress/pull/1/files#diff-e5e546dd2eb0351f813d63d1b39dbc48R29

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