eslint-plugin-kiwicom-incubator is no longer maintained, use eslint-plugin-adeira instead

Rules used at Kiwi.com in the Incubator tribe. You most probably do not need to use this package directly - use @kiwicom/eslint-config instead. This package exists basically only to workaround some Eslint limitations.

You'll first need to install ESLint. Next, install this plugin:

yarn add --dev eslint-plugin-kiwicom-incubator

Add kiwicom-incubator to the plugins section of your .eslintrc configuration file:

{
  "plugins": ["eslint-plugin-kiwicom-incubator"]
}

Then configure the rules you want to use under the rules section:

{
  "rules": {
    "kiwicom-incubator/only-nullable-fields": "error",
    "kiwicom-incubator/no-invalid-flow-annotations": "error"
  }
}

Prefers React.Node over React$Node types.

This rule disallows @noflow and @flow weak annotations. Valid annotations are @flow, @flow strict and @flow strict-local

This rule aims to remove all dangerous uses of GraphQLNonNull on GraphQL type fields. Why? It's a best practice to use nullable fields and not to rely on a returned value. This way every frontend implementation must handle the situation when API returns null because everything will break eventually. Non-nullable fields would in case of failure destroy the whole type and could bubble-up destroying the whole GraphQL response.

Examples of incorrect code for this rule:

const field = {
  arrival: {
    type: new GraphQLNonNull(GraphQLRouteStop),
    resolve: ({ arrival }: LegType): ArrivalType => arrival,
  },
};

Examples of correct code for this rule:

const field = {
  arrival: {
    type: GraphQLRouteStop,
    resolve: ({ arrival }: LegType): ArrivalType => arrival,
  },
};

Non-nullable fields are still allowed in these cases:

• inside of GraphQLInputObjectType (you want to restrict input values)
• in query or types arguments (args property)
• direct child of GraphQLList