feat: scaffold tsd tests

jest.config.tsd.js

@@ -0,0 +1,8 @@
+module.exports = {
+  displayName: {
+    color: 'blue',
+    name: 'types'
+  },
+  runner: 'jest-runner-tsd',
+  testMatch: ['**/test/test-d/*.test-d.ts']
+}

package.json

@@ -13,7 +13,8 @@
         "build:watch": "tsc --watch --preserveWatchOutput",
         "cleaner": "ts-cleaner --dist lib --watch",
         "test": "jest",
-        "test:full": "npm run build && COMPILE_EXAMPLES=1 jest",
+        "test:full": "npm run build && COMPILE_EXAMPLES=1 jest && npm run test:types",
+        "test:types": "jest --config jest.config.tsd.js",
         "test:watch": "jest --watch",
         "test:coverage": "jest --config jest.coverage.js",
         "test:coverage:watch": "jest --watchAll --config jest.coverage.js",
@@ -33,6 +34,7 @@
     },
     "homepage": "https://github.com/nullishamy/args-ts#readme",
     "devDependencies": {
+        "@tsd/typescript": "^5.2.2",
         "@types/jest": "^29.0.3",
         "@types/node": "^18.7.18",
         "@typescript-eslint/eslint-plugin": "^5.37.0",
@@ -46,6 +48,7 @@
         "eslint-plugin-tsdoc": "^0.2.17",
         "husky": "^8.0.1",
         "jest": "^29.0.3",
+        "jest-runner-tsd": "^6.0.0",
         "lint-staged": "^13.0.3",
         "nodemon": "^2.0.20",
         "ts-cleaner": "^1.0.5",

src/builder/command.ts

@@ -1,8 +1,8 @@
 import { Args, DefaultArgTypes } from '../args'
 import { CommandError } from '../error'
 import { InternalCommand } from '../internal/parse/types'
-import { ExtractArgType } from '../internal/types'
 import { CommandOpts, StoredCommandOpts, defaultCommandOpts, defaultParserOpts } from '../opts'
+import { ArgType } from '../util'
 
 /**
  * Base class for all commands, including subcommands. Any user implemented command must extend from this class.
@@ -28,14 +28,14 @@ export abstract class Command {
   // Must use any for it to accept the subtyping this function actually performs
   // Black magic happens later on to extract the real subtype out of this `any`
   abstract args: <T extends {}> (parser: Args<T>) => Args<any>
-  abstract run: (args: ExtractArgType<ReturnType<this['args']>>) => Promise<unknown>
+  abstract run: (args: ArgType<ReturnType<this['args']>>) => Promise<unknown>
 
   /**
    * Creates a runner function for use with {@link Command#run}. This exists to provide type inference to the callback, which is not available without a function call.
    * @param runFn - the run function
    * @returns - the run implementation
    */
-  runner (runFn: (args: (ExtractArgType<ReturnType<this['args']>> & DefaultArgTypes)) => Promise<unknown>): (args: ExtractArgType<ReturnType<this['args']>>) => Promise<unknown> {
+  runner (runFn: (args: (ArgType<ReturnType<this['args']>> & DefaultArgTypes)) => Promise<unknown>): (args: ArgType<ReturnType<this['args']>>) => Promise<unknown> {
     return async (args) => await runFn(args)
   }
 

src/util/index.ts

@@ -3,3 +3,4 @@ export * from './help'
 export * from './completion'
 export * from './argv'
 export * from './logging'
+export * from './types'

src/util/types.ts

@@ -0,0 +1,3 @@
+import { Args } from '../args'
+
+export type ArgType<ArgObject, Default = never> = ArgObject extends Args<infer TArgs> ? TArgs : Default

test/test-d/index.test-d.ts

@@ -0,0 +1,15 @@
+import { Args, a } from '../../src'
+import { ArgType } from '../../src/util'
+import { parserOpts } from '../shared'
+import { expectAssignable } from 'tsd-lite'
+
+describe('Type testing', () => {
+  it('infers basic flags', () => {
+    const parser = new Args(parserOpts)
+      .arg(['--flag'], a.bool())
+
+    expectAssignable<ArgType<typeof parser>>({
+      flag: true
+    })
+  })
+})

tsconfig.json

@@ -21,7 +21,7 @@
     "sourceMap": true,                        /* Generates corresponding '.map' file. */
     // "outFile": "./",                       /* Concatenate and emit output to single file. */
     "outDir": "lib",                          /* Redirect output structure to the directory. */
-    "rootDir": "src",                         /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+    //"rootDir": "src",                         /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
     // "composite": true,                     /* Enable project compilation */
     // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
     "removeComments": true,                   /* Do not emit comments to output. */