Incorrect stack trace remaps

[kitsonk]

It took me a while to narrow it down, but I had been noticing that stack traces a lot of the time were not remapping properly and I was able to narrow down a reproduction.

It requires at least two modules, where one of the modules has type annotations that are getting erased. So given:

a.ts

export interface Foo {
  a: string;
  b: string;
}

export function foo(): number {
  return (undefined as any).indexOf();
}

a_test.ts

import { test, assert } from "https://deno.land/x/std/testing/mod.ts";
import { foo } from "./a.ts";

test(function test() {
  assert.equal(foo(), 0);
});

I get the following failure and stack trace:

$ deno a_test.ts
Compiling /Users/kkelly/github/deno_std/a_test.ts
running 1 tests
test test ... FAILED
TypeError: Cannot read property 'indexOf' of undefined
    at foo (/Users/kkelly/github/deno_std/a.ts:2:22)
    at test (/Users/kkelly/github/deno_std/a_test.ts:4:18)
    at runTests (/Users/kkelly/.deno/deps/https/deno.land/x/std/testing/mod.ts:154:19)
    at fire (gen/bundle/main.js:7628:7)

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out

/Users/kkelly/.deno/deps/https/deno.land/x/std/testing/mod.ts:181:18
            throw new Error(`There were ${failed} test failures.`);

Error: There were 1 test failures.
    at setTimeout (file:///Users/kkelly/.deno/deps/https/deno.land/x/std/testing/mod.ts:245:13)
    at fire (deno/js/timers.ts:131:3)

In particular it is saying the error occurred at a.ts:2:22 which should be a.ts:7.29.

If a.ts doesn't have types, that are erased, then the mapping isn't wrong. If there is only a single module involved, even if that module exports something and contains erased types, then the mapping isn't wrong.

[ry]

Thanks good test case. I will look into it soon

[ry]

So with recent changes this is almost fixed, but not quite.

We have the ability to apply source maps and colors to exceptions using the "FormatError" op. The console.error() function apply this op if its passed an exception:

deno/js/console.ts

Lines 268 to 269 in a21a5ad

	const errorJSON = libdeno.errorToJSON(value);
	return formatError(errorJSON);

However in the testing library we print e.stack instead of e itself:
https://github.com/denoland/deno_std/blob/d895c60a51e7cdbf517fee226ffb0274904979f8/testing/mod.ts#L268

So I think the fix should be to apply this patch in deno_std

diff --git a/testing/mod.ts b/testing/mod.ts
index 06089a8..e8e00ca 100644
--- a/testing/mod.ts
+++ b/testing/mod.ts
@@ -265,7 +265,7 @@ export async function runTests() {
       result = red_failed();
       console.log("...", result);
       console.groupEnd();
-      console.error((e && e.stack) || e);
+      console.error(e);
       failed++;
       if (exitOnFail) {
         break;

When the following PR lands in core, we can close this issue: denoland/std#190

[ry]

This is fixed now.