Compiler Options

TSTyche searches for the nearest tsconfig.json that includes the test file. If none is found, it uses default compiler options.

TSConfig File

To load the compiler options for a test file, TSTyche searches for the nearest tsconfig.json which includes the file in question. If a particular test file is not included in any of the TSConfig files found in enclosing directories, default compiler options are set.

To specify the path to tsconfig.json explicitly, pass it with the --tsconfig command line option or use the tsconfig configuration option.

tsc --project ./typetests/tsconfig.json --showConfig

Language Service Plugins

To work smoothly with Svelte, Vue or similar projects, a code editor needs an additional extension to be installed. Usually, the extension provides a TypeScript language service plugin (opens in a new tab), which helps the editor to reason about typings of a project.

TSTyche makes sure the plugins are loaded, but they must be installed and explicitly listed in a TSConfig file. For example, if your type tests import from .svelte files, install the typescript-svelte-plugin package:

npm add -D typescript-svelte-plugin

And add it to the language service plugins (opens in a new tab) list in tsconfig.json:

{
  "compilerOptions": {
    "plugins": [{ "name": "typescript-svelte-plugin" }]
  }
}

Default Compiler Options

TSTyche sets the following default compiler options:

{
  "allowImportingTsExtensions": true, // not set for TypeScript 4.x
  "allowJs": true,
  "checkJs": true,
  "exactOptionalPropertyTypes": true,
  "jsx": "preserve",
  "module": "nodenext",
  "moduleResolution": "nodenext",
  "noUncheckedIndexedAccess": true,
  "noUncheckedSideEffectImports": true, // only for TypeScript >=5.6
  "resolveJsonModule": true,
  "strict": true,
  "target": "esnext",
  "verbatimModuleSyntax": true // not set for TypeScript 4.x
}