Add rule for disallowing direct barrel imports (#30)

Author: mattiamanzati

.changeset/wise-monkeys-remain.md

@@ -0,0 +1,5 @@
+---
+"@effect/eslint-plugin": patch
+---
+
+Add rule for disallowing direct barrel imports

eslint.config.mjs

@@ -1,4 +1,3 @@
-import { FlatCompat } from "@eslint/eslintrc"
 import eslint from "@eslint/js"
 import * as tsResolver from "eslint-import-resolver-typescript"
 import importPlugin from "eslint-plugin-import-x"
@@ -7,16 +6,15 @@ import sortDestructureKeys from "eslint-plugin-sort-destructure-keys"
 import * as Path from "node:path"
 import * as Url from "node:url"
 import tseslint from "typescript-eslint"
+import eslintPluginPrettier from 'eslint-plugin-prettier/recommended'
 
 const __filename = Url.fileURLToPath(import.meta.url)
 const __dirname = Path.dirname(__filename)
 
-const compat = new FlatCompat({
-  baseDirectory: __dirname,
-})
 
 export default tseslint.config(
   {
+    files: ["src/**/*.ts", "test/**/*.ts"],
     ignores: ["**/dist", "**/build", "**/docs", "**/*.md"],
   },
   eslint.configs.recommended,
@@ -111,4 +109,5 @@ export default tseslint.config(
       "@typescript-eslint/unified-signatures": "off",
     },
   },
+  eslintPluginPrettier
 )

package.json

@@ -72,7 +72,9 @@
     "prettier": "^3.3.2",
     "typescript": "^5.7.3",
     "typescript-eslint": "^8.21.0",
-    "vitest": "^3.0.4"
+    "vitest": "^3.0.4",
+    "eslint-plugin-prettier":"^5.2.6",
+    "eslint-config-prettier":"^10.1.2"
   },
   "imports": {
     "#dist/*": {

pnpm-lock.yaml

@@ -1,11 +1,13 @@
 import { dprint } from "@effect/eslint-plugin/rules/dprint"
+import { noImportFromBarrelPackage } from "@effect/eslint-plugin/rules/no-import-from-barrel-package"
 
 export const meta = {
   name: "@effect/eslint-plugin",
 }
 
 export const rules = {
   dprint,
+  noImportFromBarrelPackage,
 }
 
 // NOTE: unfortunately plugins needs a self-reference inside configs,

src/plugin.ts

@@ -0,0 +1,88 @@
+import { createRule } from "@effect/eslint-plugin/utils/eslint"
+import { AST_NODE_TYPES } from "@typescript-eslint/utils"
+import type { RuleFixer } from "@typescript-eslint/utils/ts-eslint"
+
+export type Options = {
+  packageNames: Array<string>
+}
+export type MessageIds = "replaceImport"
+
+export const noImportFromBarrelPackage = createRule<[Options], MessageIds>({
+  name: "no-import-from-barrel-package",
+  meta: {
+    type: "suggestion",
+    docs: {
+      description:
+        "Disallow importing from barrel packages, and encourages importing the specific module instead.",
+    },
+    fixable: "code",
+    messages: {
+      replaceImport: `Use import * as {{localName}} from "{{packageName}}/{{moduleName}}" instead`,
+    },
+    schema: [
+      {
+        type: "object",
+        properties: {
+          packageNames: {
+            type: "array",
+            description: "List of packages to check for barrel imports",
+            items: [
+              {
+                type: "string",
+              },
+            ],
+          },
+        },
+        additionalProperties: false,
+      },
+    ],
+  },
+  defaultOptions: [{ packageNames: [] }],
+  create: (context, options) => {
+    return {
+      ImportDeclaration: node => {
+        // destruct options
+        const [{ packageNames }] = options
+        // first we check if the import is from one of the configured modules
+        const packageName = node.source.value
+        if (packageNames.indexOf(packageName) > -1) {
+          for (const specifier of node.specifiers) {
+            // check only imports with style import {A, B} from "foo"
+            if (specifier.type === AST_NODE_TYPES.ImportSpecifier) {
+              // we are fine with type imports
+              if (specifier.importKind === "type") continue
+              const moduleName =
+                specifier.imported.type === AST_NODE_TYPES.Identifier
+                  ? specifier.imported.name
+                  : specifier.imported.value
+              const localName = specifier.local.name
+              // fix only with a single specifier
+              const fixable =
+                node.specifiers.length === 1
+                  ? {
+                      fix: (fixer: RuleFixer) =>
+                        fixer.replaceTextRange(
+                          node.range,
+                          `import * as ${localName} from "${packageName}/${moduleName}"`,
+                        ),
+                    }
+                  : {}
+              // report the error
+              context.report({
+                loc: specifier.loc,
+                node: specifier,
+                messageId: "replaceImport",
+                data: {
+                  packageName,
+                  moduleName,
+                  localName,
+                },
+                ...fixable,
+              })
+            }
+          }
+        }
+      },
+    }
+  },
+})

src/rules/no-import-from-barrel-package.ts

@@ -0,0 +1,45 @@
+import type { Options } from "@effect/eslint-plugin/rules/no-import-from-barrel-package"
+import { noImportFromBarrelPackage as rule } from "@effect/eslint-plugin/rules/no-import-from-barrel-package"
+import { ruleTester } from "@effect/eslint-plugin/test/utils/index"
+
+const options: [Options] = [{ packageNames: ["effect"] }]
+
+ruleTester.run("dprint", rule, {
+  valid: [
+    {
+      code: `import * as T from "effect/Effect"`,
+      options,
+    },
+    {
+      code: `import { Effect as Eff} from "effect/Effect"
+`,
+      options,
+    },
+    {
+      code: `import Effect from "effect/Effect"`,
+      options,
+    },
+    {
+      code: `import {type Effect } from "effect";`,
+      options,
+    },
+    {
+      code: `import {test} from "lodash";`,
+      options,
+    },
+  ],
+  invalid: [
+    {
+      code: `import { Effect } from "effect"`,
+      options,
+      errors: [{ line: 1, messageId: "replaceImport" }],
+      output: `import * as Effect from "effect/Effect"`,
+    },
+    {
+      code: `import { Effect as Eff } from "effect"`,
+      options,
+      errors: [{ line: 1, messageId: "replaceImport" }],
+      output: `import * as Eff from "effect/Effect"`,
+    },
+  ],
+})