feat(lint): add nursery rule `useImportsFirst` by terror · Pull Request #9272 · biomejs/biome

terror · 2026-02-28T04:59:40Z

Summary

Resolves #9265

This diff Implements the useImportsFirst lint rule, which enforces that all import statements appear before any non-import statements in a module. This corresponds to the ESLint import/first rule (see #9265). The rule iterates over the module item list and flags any JsImport that appears after a non-import item.

Test Plan

Snapshot tests in crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/:

invalid.js - imports after a const declaration (2 diagnostics)
invalid_mixed.js - imports interspersed with calls and exports (2 diagnostics)
valid.js - all imports grouped at the top (no diagnostics)
valid_with_export.js - single import before export and statement (no diagnostics)

Docs

Rule documentation is inline in the declare_lint_rule! macro and will be published automatically.

changeset-bot · 2026-02-28T04:59:45Z

🦋 Changeset detected

Latest commit: a784b75

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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coderabbitai · 2026-02-28T05:05:02Z

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crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid.js.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid_all_after.js.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid_mixed.js.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (1)

crates/biome_js_analyze/src/lint/nursery/use_imports_first.rs

Walkthrough

Adds a new nursery lint rule UseImportsFirst (implements biome_analyze::Rule for Ast<JsModuleItemList) that flags import statements appearing after any non‑import module item. Implements rule logic, diagnostics, and options type UseImportsFirstOptions, re-exports the options module, and registers the rule. Adds a changeset and several test specs (valid and invalid cases) under crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/.

Suggested reviewers

dyc3
ematipico

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarises the main change: adding a new nursery lint rule named useImportsFirst.
Description check	✅ Passed	The description is directly related to the changeset, explaining the rule's purpose and providing test plan details.
Linked Issues check	✅ Passed	The PR successfully implements the useImportsFirst rule as specified in issue `#9265`, enforcing imports before non-import statements.
Out of Scope Changes check	✅ Passed	All changes are scoped to implementing the new rule: rule implementation, test files, options struct, and changeset documentation.

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coderabbitai

Actionable comments posted: 1

🧹 Nitpick comments (1)

crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid.js (1)
1-5: Optional: add a directive-focused valid fixture.

Given the rule docs explicitly allow directives, a tiny valid_with_directive.js (e.g. "use strict"; then imports) would lock that behaviour in and guard regressions.

Based on learnings: Add tests for all code changes - lint rules need snapshot tests in tests/specs/{group}/{rule}/.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid.js` around
lines 1 - 5, Add a new valid fixture file (e.g., valid_with_directive.js) under
tests/specs/nursery/useImportsFirst/ that begins with a directive like "use
strict"; followed by the same import lines (import { foo } from "foo"; import {
bar } from "bar"; import { baz } from "baz"; const qux = 1;) and the same top
comment ("should not generate diagnostics") so the test suite captures that
directives are allowed by the useImportsFirst rule; ensure the file follows the
existing snapshot test pattern used in tests/specs/{group}/{rule}/ so it is
picked up by the rule tests.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/biome_rule_options/src/use_imports_first.rs`:
- Line 6: Add a rustdoc comment above the public struct UseImportsFirstOptions
explaining what this options type configures (options for the
"use-imports-first" rule/assist), what each field would control (if currently
empty, state that it has no configurable fields yet and is reserved for future
settings), and include example usage or default behavior; ensure the doc uses
standard /// rustdoc format placed immediately before the declaration of
UseImportsFirstOptions.

---

Nitpick comments:
In `@crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid.js`:
- Around line 1-5: Add a new valid fixture file (e.g., valid_with_directive.js)
under tests/specs/nursery/useImportsFirst/ that begins with a directive like
"use strict"; followed by the same import lines (import { foo } from "foo";
import { bar } from "bar"; import { baz } from "baz"; const qux = 1;) and the
same top comment ("should not generate diagnostics") so the test suite captures
that directives are allowed by the useImportsFirst rule; ensure the file follows
the existing snapshot test pattern used in tests/specs/{group}/{rule}/ so it is
picked up by the rule tests.

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⛔ Files ignored due to path filters (7)

crates/biome_configuration/src/analyzer/linter/rules.rs is excluded by !**/rules.rs and included by **
crates/biome_diagnostics_categories/src/categories.rs is excluded by !**/categories.rs and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid.js.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid_mixed.js.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid.js.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid_with_export.js.snap is excluded by !**/*.snap and included by **
packages/@biomejs/biome/configuration_schema.json is excluded by !**/configuration_schema.json and included by **

📒 Files selected for processing (7)

crates/biome_js_analyze/src/lint/nursery/use_imports_first.rs
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid.js
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid_mixed.js
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid.js
crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/valid_with_export.js
crates/biome_rule_options/src/lib.rs
crates/biome_rule_options/src/use_imports_first.rs

crates/biome_rule_options/src/use_imports_first.rs

siketyan · 2026-02-28T10:25:18Z

Restore the PR template and fill it
Please add a changeset

dyc3

Looks good, just a couple notes

crates/biome_js_analyze/src/lint/nursery/use_imports_first.rs

crates/biome_js_analyze/tests/specs/nursery/useImportsFirst/invalid.js

codspeed-hq · 2026-02-28T20:07:39Z

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 156 skipped benchmarks¹

_{Comparing terror:use-imports-first (a784b75) with main (e43e730)²}

156 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
No successful run was found on main (e49529b) during the generation of this report, so e43e730 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

dyc3

Nice work!

.changeset/add-use-imports-first.md

Netail

Would also suggest adding a test with a directive at the beginning of a file

crates/biome_js_analyze/src/lint/nursery/use_imports_first.rs

crates/biome_rule_options/src/use_imports_first.rs

ematipico · 2026-03-01T06:08:39Z

crates/biome_js_analyze/src/lint/nursery/use_imports_first.rs

+                rule_category!(),
+                range,
+                markup! {
+                    "This import should appear at the top of the module."


This message doesn't align with the rule pillars. The message must tell what's the error, not the solution. It should say something like "This import shouldn't be here" or something.

Just changed this up. I believe I now follow what 'what', 'why' and 'how' structure we're aiming for.

feat(lint): add nursery rule useImportsFirst

c6d9702

github-actions bot added A-Project Area: project A-Linter Area: linter L-JavaScript Language: JavaScript and super languages A-Diagnostic Area: diagnostocis labels Feb 28, 2026

coderabbitai bot reviewed Feb 28, 2026

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terror added 2 commits February 28, 2026 12:09

Add changeset

e5f5245

Merge branch 'main' into use-imports-first

e4594c0

dyc3 requested changes Feb 28, 2026

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terror added 2 commits February 28, 2026 12:21

fix(lint): add "why" note to useImportsFirst diagnostic

bb4718f

test(lint): add useImportsFirst test with all imports after statements

2a6ad5c

[autofix.ci] apply automated fixes

70dec32

github-actions bot added the A-CLI Area: CLI label Feb 28, 2026

dyc3 approved these changes Feb 28, 2026

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Netail reviewed Feb 28, 2026

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terror added 4 commits February 28, 2026 21:41

docs(lint): fix changeset wording for useImportsFirst

0246a34

refactor(lint): use UseImportsFirstOptions instead of unit type

241311f

test(lint): add useImportsFirst test with directive before imports

2e78c65

Merge branch 'main' into use-imports-first

10f3274

ematipico requested changes Mar 1, 2026

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fix(lint): reword useImportsFirst diagnostic to describe the error

a784b75

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Merging this PR will not alter performance

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