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test: change common.expectsError() signature
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One downside to `common.expectsError()` is that it increases the
abstractions people have to learn about in order to work with even
simple tests. Whereas before, all they had to know about is
`assert.throws()`, now they have to *also* know about
`common.expectsError()`. This is very different (IMO) from
`common.mustCall()` in that the latter has an intuitively understandable
name, accepts arguments as one would expect, and (in most cases) doesn't
actually require reading documentation or code to figure out what it's
doing. With `common.expectsError()`, there's a fair bit of magic. Like,
it's not obvious what the first argument would be. Or the second. Or the
third. You just have to know.

This PR changes the arguments accepted by `common.expectsError()` to a
single settings object. Someone coming across this has a hope of
understanding what's going on without reading source or docs:

```js
const validatorFunction = common.expectsError({code: 'ELOOP',
                                               type: Error,
                                               message: 'foo'});
```

This, by comparison, is harder to grok:

```js
const validatorFunction = common.expectsError('ELOOP',
                                               Error,
                                               'foo');
```

And this is especially wat-inducing:

```js
common.expectsError(undefined, undefined, 'looped doodad found');
```

It's likely that only people who work with tests frequently can be
expected to remember the three arguments and their order. By comparison,
remembering that the error code is `code` and the message is `message`
might be manageable.
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Trott committed Feb 25, 2017
1 parent ee7b7f6 commit cd0b321
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Showing 6 changed files with 28 additions and 24 deletions.
22 changes: 12 additions & 10 deletions test/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -187,16 +187,18 @@ Platform normalizes the `dd` command

Check if there is more than 1gb of total memory.

### expectsError(code[, type[, message]])
* `code` [<String>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type)
expected error must have this value for its `code` property
* `type` [<Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function)
expected error must be an instance of `type`
* `message` [<String>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type)
or [<RegExp>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp)
if a string is provided for `message`, expected error must have it for its
`message` property; if a regular expression is provided for `message`, the
regular expression must match the `message` property of the expected error
### expectsError(settings)
* `settings` [<Object>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)
with the following optional properties:
* `code` [<String>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type)
expected error must have this value for its `code` property
* `type` [<Function>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function)
expected error must be an instance of `type`
* `message` [<String>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type)
or [<RegExp>](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp)
if a string is provided for `message`, expected error must have it for its
`message` property; if a regular expression is provided for `message`, the
regular expression must match the `message` property of the expected error

* return function suitable for use as a validation function passed as the second
argument to `assert.throws()`
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2 changes: 1 addition & 1 deletion test/common.js
Original file line number Diff line number Diff line change
Expand Up @@ -625,7 +625,7 @@ exports.WPT = {
};

// Useful for testing expected internal/error objects
exports.expectsError = function expectsError(code, type, message) {
exports.expectsError = function expectsError({code, type, message}) {
return function(error) {
assert.strictEqual(error.code, code);
if (type !== undefined)
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7 changes: 2 additions & 5 deletions test/parallel/test-debug-agent.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,6 @@ const debug = require('_debug_agent');

assert.throws(
() => { debug.start(); },
common.expectsError(
undefined,
assert.AssertionError,
'Debugger agent running without bindings!'
)
common.expectsError({ type: assert.AssertionError,
message: 'Debugger agent running without bindings!' })
);
3 changes: 2 additions & 1 deletion test/parallel/test-http-request-invalid-method-error.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,5 +5,6 @@ const http = require('http');

assert.throws(
() => { http.request({method: '\0'}); },
common.expectsError(undefined, TypeError, 'Method must be a valid HTTP token')
common.expectsError({ type: TypeError,
message: 'Method must be a valid HTTP token' })
);
16 changes: 10 additions & 6 deletions test/parallel/test-internal-errors.js
Original file line number Diff line number Diff line change
Expand Up @@ -82,35 +82,39 @@ assert.throws(
assert.doesNotThrow(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1'));
}, common.expectsError({ code: 'TEST_ERROR_1' }));
});

assert.doesNotThrow(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1', TypeError, /^Error for testing/));
}, common.expectsError({ code: 'TEST_ERROR_1',
type: TypeError,
message: /^Error for testing/ }));
});

assert.doesNotThrow(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1', TypeError));
}, common.expectsError({ code: 'TEST_ERROR_1', type: TypeError }));
});

assert.doesNotThrow(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1', Error));
}, common.expectsError({ code: 'TEST_ERROR_1', type: Error }));
});

assert.throws(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1', RangeError));
}, common.expectsError({ code: 'TEST_ERROR_1', type: RangeError }));
}, /^AssertionError: .+ is not the expected type \S/);

assert.throws(() => {
assert.throws(() => {
throw new errors.TypeError('TEST_ERROR_1', 'a');
}, common.expectsError('TEST_ERROR_1', TypeError, /^Error for testing 2/));
}, common.expectsError({ code: 'TEST_ERROR_1',
type: TypeError,
message: /^Error for testing 2/ }));
}, /AssertionError: .+ does not match \S/);
2 changes: 1 addition & 1 deletion test/parallel/test-require-invalid-package.js
Original file line number Diff line number Diff line change
Expand Up @@ -5,5 +5,5 @@ const assert = require('assert');

// Should be an invalid package path.
assert.throws(() => require('package.json'),
common.expectsError('MODULE_NOT_FOUND')
common.expectsError({ code: 'MODULE_NOT_FOUND' })
);

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