solo_lints 0.1.5

Analyzer plugin for solo and flutter_solo: a job in its own queue, a shared key, a needless ignoreFailure(), and the rules of async_job_lints for the core.

solo_lints

solo_lints is an analyzer plugin for code built on solo and flutter_solo. It reports the mistakes that compile, run and often pass a first test: a wait in cleanup that never happens, a resource lost to a cancellation, a catch that resets a working device, a job that waits for itself, one key for every request, a wait that a cancellation does not end. Most rules stand for a section of Common mistakes, the page of solo that shows each mistake and the right way side by side.

The rules of the core, async_job, come from async_job_lints, and this plugin includes them: code on solo needs only solo_lints. Name one of the two plugins, not both: the analysis server resolves the versions of all plugins together, and when they disagree, no plugin runs.

Also on the documentation site, with search.

Install

Name the plugin in analysis_options.yaml at the root of the package or the workspace:

plugins:
  solo_lints: ^0.1.5

The analysis server fetches the plugin itself, so it is not a dependency in pubspec.yaml. Plugins need Dart 3.10 or later. dart analyze and the editor report its diagnostics. Run dart analyze on the root of the package or on single files: on a folder below the root, such as dart analyze lib, it shows none of them. flutter analyze reports them on Flutter 3.38, but from Flutter 3.44 on it shows none of them; in a Flutter package, run dart analyze for the plugin. An editor sees a change to the plugins section after its analysis server restarts.

The warnings are on as soon as the plugin is named. The four lints, catch_without_check, key_per_request, ignore_failure_hides_bugs and bare_await, are turned on by name:

plugins:
  solo_lints:
    version: ^0.1.5
    diagnostics:
      catch_without_check: true
      key_per_request: true
      ignore_failure_hides_bugs: true
      bare_await: true

A rule takes a severity in place of true: error, warning or info. key_per_request: warning turns the lint on as a warning, and dart analyze then fails on it, as on any warning. false turns a warning off.

A diagnostic is silenced with the name of the plugin in front of the rule: // ignore: solo_lints/ctx_in_cleanup on the line above it, or // ignore_for_file: solo_lints/ctx_in_cleanup for the whole file.

The quick fixes are offered in the editor. dart fix does not apply them: it applies the fixes of the analyzer itself, not those of plugins.

On Dart 3.12, dart analyze in a package that names a plugin prints each diagnostic of the analyzer itself twice. Dart 3.13 prints it once.

Rules

Rule	Kind	Reports
ctx_in_cleanup	warning	a waiting member of the context called in cleanup
release_on_the_call	warning	a release registered on the line under the call that brings the resource
catch_without_check	lint	a broad catch in a body that acts before asking the job
sync_fake_async	warning	an async callback of fakeAsync
await_own_queue	warning	a job that waits for a job of its own controller's queue
key_per_request	lint	one key for a Policy.droppable job whose body reads an argument
ignore_failure_hides_bugs	lint	ignoreFailure() on a job that names its expected errors
bare_await	lint	an await in a job body that does not go through the context

The five rules of the core are described in the README of async_job_lints: their names in the table lead to their sections there. There // ignore: puts async_job_lints/ in front of a rule; with this plugin named, it is solo_lints/, as for the three rules below.

await_own_queue

Job<void> syncAndRecord(int item) =>
    enqueue<Ready, void>(key: _Op.syncAndRecord, (ctx) async {
      final path = await sync(item).value; // await_own_queue
      await recordPath(path).value; // await_own_queue
    });

sync(item) queues a job behind the one that waits for it, and nothing moves until close() cancels both. Run the job through ctx.run(_sync(item)) instead. The rule takes a method of the same controller that brings a SoloJob, by its declared type or by what it returns when it is declared in the same file, and close() and cancelAll(). It looks at the body of a SoloContext job queued on this controller, what the body returns included, at the actions that body waits for through join, abandonable and uncancellable, and at its cleanup, which the queue waits for as well. A mixin on Solo is the controller too. bare_await, which reports the other plain waits of a body, is quiet on these. See Steps as children.

key_per_request

Job<Profile> load(String id) => enqueue<Ready, Profile>(
  key: _Op.load, // key_per_request
  policy: Policy.droppable,
  (ctx) => ctx.abandonable(() => api.load(id)),
);

A policy compares keys, not arguments. With one key for every load(id), Policy.droppable takes load('grace'), called while load('ada') runs, for a duplicate and hands its caller Ada's profile. Put the argument into the key: key: (_Op.load, id). The rule takes enqueue of Solo with Policy.droppable and enqueueJob of a job with that policy, when the key reads no parameter of the enclosing method or function and the body reads one. A key that reads a local variable or a parameter of a closure is left alone. It is a lint rather than a warning because one key is sometimes meant, when the result does not depend on the argument. See A key for each request.

The quick fix replaces the key K with the record (K, a, b) of the parameters the body reads. It is offered when each of them compares by value: a String, a number, a bool, an enum, or one of those that can be null.

ignore_failure_hides_bugs

SoloJob<Profile> load() => enqueue<Ready, Profile>(
  (ctx) => api.load(),
  isExpectedError: (e) => e is ApiException,
);

profiles.load().ignoreFailure(); // ignore_failure_hides_bugs

isExpectedError already keeps the errors it names quiet and lets the bugs through to the zone, and ignoreFailure() hides those as well. Drop ignoreFailure(): the expected errors stay quiet, and a bug is still reported. The rule takes ignoreFailure() on a job that comes from job or enqueue with isExpectedError, or from the add of a collect or accumulate field with one, also through a method or function of the same library whose body is => or a single return, when nobody uses the job afterwards: the call itself, or a cascade whose value is dropped, as the onPressed of a button is. The page of common mistakes has no section for this one. It is a lint rather than a warning because a job whose outcome nobody needs, with the reporting left to the hooks, may call ignoreFailure() on purpose: see Answering for every failure.

Versions

The plugin works on Dart 3.10 and later, with analyzer from 12.1 to 14. A Dart SDK that needs analyzer 15 does not load this version, and its rules stay silent until a release lifts the bound.

The rules know the types of solo by their names and the library they come from, without depending on the package. On a version of solo where a name has changed, a rule stays silent rather than reports code that is right. The rules of the core are those of async_job_lints, and its CHANGELOG lists their changes.