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chore(cause): added error cause #32

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chore(cause): added error cause #32

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64696bf
chore(cause): added error cause
Mar 5, 2025
6a0e596
chore(error): added error cause to file read
Mar 5, 2025
37d5cde
chore(test): added error cause and fixed tests
Mar 5, 2025
910b84b
fix(handler): added more information to error cause
Mar 6, 2025
a9f512f
fix(error): made error readable
Mar 6, 2025
30426b7
fix(error): made error readable
Mar 6, 2025
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10 changes: 7 additions & 3 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ function isModule(file) {
// and try to load it as javascript. That won't work for this case.
var ext = path.extname(file);
// in order for this to work after deprecation of module.extensions
var extensions = {'.js': true, '.json': true, '.node': true}
var extensions = {'.js': true, '.json': true, '.node': true};
return ext === '' || extensions.hasOwnProperty(ext);
}

Expand All @@ -47,15 +47,19 @@ exports.create = function create(parent) {

fs.readFile(file, 'utf8', function (err, data) {
if (err) {
callback(err);
callback(new Error(`Error occured while reading file: ${file}`, {
cause: err
}));
return;
}

try {
data = JSON.parse(data);
resolve(data, file, callback);
} catch (err) {
callback(err);
callback(new Error('Error occured while parsing JSON data', {
cause: err
}));
}
});
}
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8 changes: 6 additions & 2 deletions lib/resolver.js
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Expand Up @@ -162,7 +162,9 @@ exports.create = function create(parent) {
}

async.parallel(tasks, function (err, data) {
err ? callback(err) : callback(null, data);
err ? callback(new Error('Error occured while resolving protocols in case data is of type object/array', {
cause: err,
})) : callback(null, data);
});

} else if (thing.isString(data)) {
Expand All @@ -188,7 +190,9 @@ exports.create = function create(parent) {
try {
data = handler(input);
} catch (err) {
error = err;
error = new Error('Error occured while resolving protocols in case data is of type string', {
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@jonathansamines jonathansamines Mar 5, 2025 •
edited
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IIRC, ultimately only this "string" keys actually result in meaningful work that can cause external failures. On a typical configuration resolved through shorstop, you'll have something like:

{
  "complex": {
    "key": "protocol-a:first-value",
    "other": [
       { "child": "protocol-b:second-value" }
    ]
  }
}

In the example above, ultimately only leaf nodes (e.g strings) are actually processed through shorstop handlers, and therefore yield external work. Other intermediate nodes are either only traversed (e.g objects or arrays) or ignored (e.g other primitives).

So this is probably the most meaningful piece of code we can instrument with an additional error in the causal chain. As it contains key information that could help us identify the underlying issue:

  • What "protocol" we were processing when the failure happened?
  • What "value" we were processing when the failure happened?
  • What "handler" we were processing when the failure happened? (A note here, handlers are not typically named, but we can always try to guess by using the function name and fallback to something like "unknown" in case of anonymous functions)

For the sample configuration above, I would expect errors to contain all of that information:

Error occurred while resolving "protocol-a" protocol with value "first-value" at "handlerNameOrUnknown" handler.
 ...
 cause ...

Without this information, this intermediate error in the causal chain is not really useful, and will only be additional noise in our logs.

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@jonathansamines new information added.

cause: err,
});
}

done(error, data);
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7 changes: 5 additions & 2 deletions test/index.js
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Expand Up @@ -229,7 +229,8 @@ test('shortstop', function (t) {
expected = { foo: 'foo:foo', bar: false };
resolver.resolve(expected, function resolve(err, actual) {
t.ok(err);
t.equal(err.message, 'fail');
t.equal(err.message, 'Error occured while resolving protocols in case data is of type object/array');
t.equal(err.cause.message, 'fail');
t.notOk(actual);
t.end();
});
Expand All @@ -247,7 +248,9 @@ test('shortstop', function (t) {
expected = { foo: 'test:foo', bar: false };
resolver.resolve(expected, function resolve(err, actual) {
t.ok(err);
t.equal(err.message, 'fail');
t.equal(err.message, 'Error occured while resolving protocols in case data is of type object/array');
t.equal(err.cause.message, 'Error occured while resolving protocols in case data is of type string');
t.equal(err.cause.cause.message, 'fail');
t.notOk(actual);
t.end();
});
Expand Down