assert: wrap validation function errors

This makes sure that validation function used by `assert.throws` and
`assert.rejects` always throw validatin errors instead of rethrowing
the received error.

That should improve the debugging experience for developers since
they have a better context where the error is coming from and they
also get to know what triggered it.

PR-URL: https://github.com/nodejs/node/pull/28263
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/lib/assert.js b/lib/assert.js
index 1beb33265d..3d54dcd63f 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -653,7 +653,21 @@ function expectedException(actual, expected, message, fn) {
   // Check validation functions return value.
   const res = expected.call({}, actual);
   if (res !== true) {
-    throw actual;
+    if (!message) {
+      generatedMessage = true;
+      const name = expected.name ? `"${expected.name}" ` : '';
+      message = `The ${name}validation function is expected to return "true".` +
+        ` Received ${inspect(res)}`;
+    }
+    const err = new AssertionError({
+      actual,
+      expected,
+      message,
+      operator: fn.name,
+      stackStartFn: fn
+    });
+    err.generatedMessage = generatedMessage;
+    throw err;
   }
 }