`t.throws()` with regex not working as expected

[stevenvachon]

This fails:

t.throws(() => { throw new TypeError("Invalid URL: http://") }, /^Invalid URL/)

... yet:

/^Invalid URL/.test("Invalid URL: http://")
//-> true

error can be an error constructor, error message, regex matched against the error message, or validation function.

[sindresorhus]

Underneath we're using the Node.js core assert.throws method and it seems it uses error.toString() instead of error.message for the regex testing.

Yet another reason we should do our own implementation of throws().

assert.throws(() => {
  throw new Error('foobar');
}, /^foo/);
/*
Error: foobar
    at assert.throws (repl:1:29)
    at _tryBlock (assert.js:489:5)
    at _throws (assert.js:510:12)
    at Function.throws (assert.js:540:3)
    at repl:1:8
    at ContextifyScript.Script.runInThisContext (vm.js:44:33)
    at REPLServer.defaultEval (repl.js:239:29)
    at bound (domain.js:301:14)
    at REPLServer.runBound [as eval] (domain.js:314:12)
    at REPLServer.onLine (repl.js:433:10)
*/

assert.throws(() => {
  throw new Error('foobar');
}, /^Error: foo/);
//=> undefined