[no-duplicates] invalid fix when there are 3 imports with named imports and dangling commas

[bradzacher]

Input:

import {A1,} from 'foo';
import {B1,} from 'foo';
import {C1,} from 'foo';

import {
  A2,
} from 'bar';
import {
  B2,
} from 'bar';
import {
  C2,
} from 'bar';

Expected:

Error and fixed to

import {A1,B1,C1,} from 'foo';
import {
  A2,
  B2,
  C2,
} from 'bar';

(or something similar)

Actual:

Error and fixed to

import {A1,B1,,C1,} from 'foo';
              ^ SYNTAX ERROR
import {
  A2,

  B2,
,
^ SYNTAX ERROR
  C2,
} from 'bar';

---

Interestingly this bug requires 3 (or more) duplicate declarations to trigger.

I haven't looked yet - but given it happens for 3 and not 2 - I'd assume that ESLint is merging the distinct fixes poorly - leading to the syntax error.

[AngusMacrae]

facing this bug too, can confirm it only occurs with 3 or more duplicate import paths

[ljharb]

Tests pass on latest master with this snippet, so I'll close this shortly when I push those up.

[bradzacher]

@ljharb the ESLint rule tester might not pick this up? Depends how it composites fixes together I guess. Might be worth a quick whirl as a manual test against a file with the CLI to triple check.

[ljharb]

I’ve not run into any cases like that with the rule tester; could you make a small repro repo?

[bradzacher]

Hmm - investigating more this appears to be working fine now yeah.
Some combination of the latest ESLint version and the latest plugin version appears to have fixed it.