Testing TypeScript compilation (should succeed or should fail)

1. put tsconfig.json into test directory.

   "noEmit" is recommended.

   {
       "compilerOptions": {
           "target": "es5",
           "module": "commonjs",
           "noEmit": true,
           "strictNullChecks": true
       },
       "filesGlob": [
           "*.ts"
       ],
       "exclude": [
           "node_modules"
       ]
   }

2. put files to be tested into test directory.

   // should-succeed.ts
   
   interface Foo { foo: string; }
   
   export function test(foo: Foo) {
       console.log(foo.foo);
   }

   When compilation errors should be occurred, write error code inline after 4 slashes(////).

   // should-fail-1.ts
   
   interface Foo { foo: string; }
   
   export function test(foo: Foo) {
       console.log(foo.bar);       //// TS2339
   }

   You can write part of error message after error code. (with colon)

   // should-fail-2.ts
   
   interface Foo { foo: string; }
   
   export function test(foo: Foo) {
       console.log(foo.bar);       //// TS2339: Property 'bar' does not exist on
   }

   Or regular expression.

   // should-fail-3.ts (but this code is not wrong acturally ...)
   
   interface Foo { foo: string; }
   
   export function test(foo: Foo) {
       console.log(foo.foo);       //// TS2339: /property .* does not exist/i
   }

3. run tsc-test command

   $ tsc-test -p test/tsconfig.json
   

   And you will get output like below:

   OK: test/should-fail-1.ts
   OK: test/should-fail-2.ts
   NG: test/should-fail-3.ts
   OK: test/should-succeed.ts
   
   test/should-fail-3.ts:6
     expected: TS2339: /property .* does not exist/i
     bat was:  <no error>
   

// runner.ts

import test from "ava";
import { Tester, formatFailureMessage } from "tsc-test";

const tester = Tester.fromConfig("<path to tsconfig.json>");
tester.sources.forEach(fileName => {
    test(fileName, t => {
        const failures = tester.test(fileName);
        if (failures.length > 0) {
            t.fail(formatFailureMessage(...failures));
        }
    })
});

MIT