Merge pull request #15 from dotcore64/chore/use-tsd

Replace tsc with tsd for type testing

.eslintrc.json

@@ -7,7 +7,8 @@
   },
   "rules": {
     "unicorn/prevent-abbreviations": 0,
-    "eslint-comments/no-unused-disable": "error"
+    "eslint-comments/no-unused-disable": "error",
+    "import/no-extraneous-dependencies": ["error", { "devDependencies": ["index.test-d.ts", "test/*.js"] }]
   },
   "overrides": [
     {
@@ -33,5 +34,15 @@
         "@typescript-eslint/no-redeclare": ["error"]
       }
     }
-  ]
+  ],
+  "settings": {
+    "import/parsers": {
+      "@typescript-eslint/parser": [".ts"]
+    },
+    "import/resolver": {
+      "typescript": {
+        "alwaysTryTypes": true
+      }
+    }
+  }
 }

test/types.ts → index.test-d.ts

@@ -1,39 +1,40 @@
-// eslint-disable-next-line import/no-unresolved,n/no-extraneous-import
+// eslint-disable-next-line n/no-extraneous-import
 import fromCallback from 'p-from-callback';
+import { expectAssignable, expectType } from 'tsd';
 
-fromCallback((cb) => cb(undefined, 'foo')) as Promise<'foo'>;
-fromCallback((cb) => cb(undefined, 'foo')) as Promise<string>;
+expectType<Promise<'foo'>>(fromCallback((cb) => cb(undefined, 'foo')));
+expectAssignable<Promise<string>>(fromCallback((cb) => cb(undefined, 'foo')));
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo')) as Promise<number>;
-fromCallback<'foo'>((cb) => cb(undefined, 'foo')) as Promise<'foo'>;
+expectType<Promise<'foo'>>(fromCallback<'foo'>((cb) => cb(undefined, 'foo')));
 
-fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<string>;
-fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<'foo'>;
+expectAssignable<Promise<string>>(fromCallback((cb) => cb(undefined, 'foo', 'bar')));
+expectType<Promise<'foo'>>(fromCallback((cb) => cb(undefined, 'foo', 'bar')));
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<'bar'>;
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<number>;
-fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<string>;
-fromCallback((cb) => cb(undefined, 'foo'), true) as Promise<string[]>;
+expectAssignable<string>(await fromCallback((cb) => cb(undefined, 'foo', 'bar')));
+expectAssignable<string[]>(await fromCallback((cb) => cb(undefined, 'foo'), true));
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo'), true) as Promise<string>;
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo', 'bar')) as Promise<string[]>;
-fromCallback((cb) => cb(undefined, 'foo', 'bar'), true) as Promise<string[]>;
+expectAssignable<string[]>(await fromCallback((cb) => cb(undefined, 'foo', 'bar'), true));
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo', 'bar'), true) as Promise<number[]>;
 
-fromCallback((cb) => cb()) as Promise<undefined>;
+expectType<undefined>(await fromCallback((cb) => cb()));
 // eslint-disable-next-line unicorn/no-useless-undefined
-fromCallback((cb) => cb(undefined, undefined)) as Promise<undefined>;
-fromCallback((cb) => cb(new Error('message'))) as Promise<undefined>;
+expectType<undefined>(await fromCallback((cb) => cb(undefined, undefined)));
+expectType<undefined>(await fromCallback((cb) => cb(new Error('message'))));
 // @ts-expect-error
 fromCallback((cb) => cb(new Error('message'), 'foo')) as Promise<undefined>;
 // @ts-expect-error
 fromCallback((cb) => cb(new Error('message'))) as Promise<number>;
 
-fromCallback((cb) => cb(), true) as Promise<[]>;
-fromCallback((cb) => cb('foo'), true) as Promise<[]>;
+expectType<[]>(await fromCallback((cb) => cb(), true));
+expectType<[]>(await fromCallback((cb) => cb('foo'), true));
 // @ts-expect-error
 fromCallback((cb) => cb(), true) as Promise<undefined>;
 // @ts-expect-error
@@ -45,9 +46,9 @@ fromCallback((cb) => cb('error', 'foo'), true) as Promise<undefined>;
 fromCallback((cb) => cb === 'foo');
 
 let foo: boolean;
-fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo) as Promise<string>;
-fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo) as Promise<string[]>;
-fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo) as Promise<string | string[]>;
+expectAssignable<string>(await fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo));
+expectAssignable<string[]>(await fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo));
+expectAssignable<string | string[]>(await fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo));
 // @ts-expect-error
 fromCallback((cb) => cb(undefined, 'foo', 'bar'), foo) as Promise<number>;
 // @ts-expect-error