qtlint linter for qt

[denisvmedia]

Hi everyone,

Maintaining idiomatic quicktest assertions across a growing test suite can be non-trivial, and small inconsistencies tend to accumulate over time.

I created a quicktest-specific linter that detects suboptimal or non-idiomatic assertion patterns and can automatically apply fixes: https://github.com/go-extras/qtlint

The linter is intentionally focused on quicktest semantics rather than generic test linting, and the rule set is designed to be minimal and extensible.

Contributions, ideas for additional rules, and feedback are welcome.

[denisvmedia]

New qtlint version released: https://github.com/go-extras/qtlint/releases/tag/v1.3.0. Total list of supported detects and fixes:

Detecting qt.Not(qt.IsNil) and suggesting qt.IsNotNil
Detecting qt.Not(qt.IsTrue) and suggesting qt.IsFalse
Detecting qt.Not(qt.IsFalse) and suggesting qt.IsTrue
Detecting len(x), qt.Equals and suggesting x, qt.HasLen
Detecting x == y, qt.IsTrue and suggesting x, qt.Equals, y
Detecting x == y, qt.IsFalse and suggesting x, qt.Not(qt.Equals), y
Detecting x != y, qt.IsTrue and suggesting x, qt.Not(qt.Equals), y
Detecting x != y, qt.IsFalse and suggesting x, qt.Equals, y
Detecting x == nil, qt.IsTrue and suggesting x, qt.IsNil
Detecting x == nil, qt.IsFalse and suggesting x, qt.IsNotNil
Detecting x != nil, qt.IsTrue and suggesting x, qt.IsNotNil
Detecting x != nil, qt.IsFalse and suggesting x, qt.IsNil
Detecting strings.Contains(x, y), qt.IsTrue and suggesting x, qt.Contains, y
Detecting strings.Contains(x, y), qt.IsFalse and suggesting x, qt.Not(qt.Contains), y
Detecting slices.Contains(x, y), qt.IsTrue and suggesting x, qt.Contains, y
Detecting slices.Contains(x, y), qt.IsFalse and suggesting x, qt.Not(qt.Contains), y
Detecting if err != nil { t.Fatal[f](...) } and suggesting c.Assert(err, qt.IsNil, qt.Commentf(...))
Detecting if err != nil { t.Error[f](...) } and suggesting c.Check(err, qt.IsNil, qt.Commentf(...))

[denisvmedia]

Two new qtlint releases since v1.3.0:

v1.4.0 — extends the HasLen rule

Detecting len(x), qt.Not(qt.Equals) and suggesting x, qt.Not(qt.HasLen)

v1.5.0 — new errors.Is / errors.As rule + auto-fix for if err != nil

New detections:

Detecting errors.Is(err, target), qt.IsTrue and suggesting err, qt.ErrorIs, target
Detecting errors.Is(err, target), qt.IsFalse and suggesting err, qt.Not(qt.ErrorIs), target
Detecting errors.As(err, &target), qt.IsTrue and suggesting err, qt.ErrorAs, &target
Detecting errors.As(err, &target), qt.IsFalse and suggesting err, qt.Not(qt.ErrorAs), &target

Auto-fix news. The two if err != nil { t.Fatal/Error[f](...) } rules that previously reported diagnostics only now ship with auto-fix, rewriting the block into c.Assert/Check(err, qt.IsNil[, qt.Commentf(...)]). Because t.Fatal's Sprintln join can only be approximated through a synthesized qt.Commentf format, the rewrite is classified per variant:

• stable (semantics preserved exactly): t.Fatal(err), t.Fatal(), t.Fatalf("literal", args...)
• best-effort (close but with a small failure-message drift): multi-arg t.Fatal("msg:", err, 123), non-literal t.Fatalf(formatVar, ...), single non-err arg
• no fix (would change scoping or args are opaque): if err := f(); err != nil { ... }, t.Fatal(args...) spread

A new -only-stable-fixes flag withholds the best-effort SuggestedFix (the diagnostic still fires), so qtlint -fix -only-stable-fixes ./... only touches rewrites whose semantics are preserved exactly. The flag is registered on Analyzer.Flags and propagates automatically to both the standalone CLI and golangci-lint.