Fix: Ignore re-export all in no-duplicate-imports (fixes #12760)

eslint · Jan 10, 2020 · 8ed3115 · 8ed3115
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diff --git a/docs/rules/no-duplicate-imports.md b/docs/rules/no-duplicate-imports.md
@@ -37,14 +37,16 @@ import something from 'another-module';
 
 This rule takes one optional argument, an object with a single key, `includeExports` which is a `boolean`. It defaults to `false`.
 
-If re-exporting from an imported module, you should add the imports to the `import`-statement, and export that directly, not use `export ... from`.
+### includeExports
+
+If the `includeExports` option is set to `true`, this rule will also require that all named re-exports from a single module exist in a single `export` statement.
 
 Example of **incorrect** code for this rule with the `{ "includeExports": true }` option:
 
 ```js
 /*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/
 
-import { merge } from 'module';
+export { merge } from 'module';
 
 export { find } from 'module';
 ```
@@ -54,6 +56,26 @@ Example of **correct** code for this rule with the `{ "includeExports": true }`
 ```js
 /*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/
 
+export { merge, find } from 'module';
+```
+
+Additionally, if re-exporting from an imported module, you should add the imports to the `import`-statement, and export that directly, not use `export ... from`.
+
+Example of additional **incorrect** code for this rule with the `{ "includeExports": true }` option:
+
+```js
+/*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/
+
+import { merge } from 'module';
+
+export { find } from 'module';
+```
+
+Example of additional **correct** code for this rule with the `{ "includeExports": true }` option:
+
+```js
+/*eslint no-duplicate-imports: ["error", { "includeExports": true }]*/
+
 import { merge, find } from 'module';
 
 export { find };

diff --git a/lib/rules/no-duplicate-imports.js b/lib/rules/no-duplicate-imports.js
@@ -134,7 +134,6 @@ module.exports = {
 
         if (includeExports) {
             handlers.ExportNamedDeclaration = handleExports(context, importsInFile, exportsInFile);
-            handlers.ExportAllDeclaration = handleExports(context, importsInFile, exportsInFile);
         }
 
         return handlers;

diff --git a/tests/lib/rules/no-duplicate-imports.js b/tests/lib/rules/no-duplicate-imports.js
@@ -45,6 +45,34 @@ ruleTester.run("no-duplicate-imports", rule, {
         {
             code: "import { merge } from \"lodash-es\";\nexport { merge as lodashMerge }",
             options: [{ includeExports: true }]
+        },
+
+        // ignore `export * from` declarations, they cannot be merged with any other import/export declarations
+        {
+            code: "import os from 'os'; export * from 'os';",
+            options: [{ includeExports: true }]
+        },
+        {
+            code: "export * from 'os'; import { a } from 'os';",
+            options: [{ includeExports: true }]
+        },
+        {
+            code: "import * as ns from 'os'; export * from 'os';",
+            options: [{ includeExports: true }]
+        },
+        {
+            code: "export * from 'os'; export { a } from 'os';",
+            options: [{ includeExports: true }]
+        },
+        {
+            code: "export { a as b } from 'os'; export * from 'os';",
+            options: [{ includeExports: true }]
+        },
+
+        // this is probably an exporting error, but that isn't a responsibility of this rule
+        {
+            code: "export * from 'os'; export * from 'os';",
+            options: [{ includeExports: true }]
         }
     ],
     invalid: [
@@ -80,9 +108,9 @@ ruleTester.run("no-duplicate-imports", rule, {
             errors: [{ messageId: "exportAs", data: { module: "os" }, type: "ExportNamedDeclaration" }]
         },
         {
-            code: "import os from \"os\";\nexport * from \"os\";",
+            code: "import os from 'os'; export * from 'os'; export { a } from 'os';",
             options: [{ includeExports: true }],
-            errors: [{ messageId: "exportAs", data: { module: "os" }, type: "ExportAllDeclaration" }]
+            errors: [{ messageId: "exportAs", data: { module: "os" }, type: "ExportNamedDeclaration" }]
         }
     ]
 });