Add export ... from ... support

sindresorhus · Jul 18, 2020 · ce6d268 · ce6d268
1 parent 4e08529
commit ce6d268
Show file tree

Hide file tree

Showing 3 changed files with 113 additions and 0 deletions.
diff --git a/docs/rules/import-style.md b/docs/rules/import-style.md
@@ -78,6 +78,13 @@ Default: `true`
 
 Pass `"checkDynamicImport": false` to disable linting of dynamic import statements (like `await import('foo')`) completely.
 
+### checkExportFrom
+
+Type: `boolean`\
+Default: `false`
+
+Pass `"checkExportFrom": true` to enable linting of export-from statements (like `export ... from 'foo'`).
+
 ### checkRequire
 
 Type: `boolean`\

diff --git a/rules/import-style.js b/rules/import-style.js
@@ -39,6 +39,30 @@ const getActualImportDeclarationStyles = importDeclaration => {
 	return [...styles];
 };
 
+const getActualExportDeclarationStyles = exportDeclaration => {
+	const {specifiers} = exportDeclaration;
+
+	if (specifiers.length === 0) {
+		return ['unassigned'];
+	}
+
+	const styles = new Set();
+
+	for (const specifier of specifiers) {
+		if (specifier.type === 'ExportSpecifier') {
+			if (specifier.exported.type === 'Identifier' && specifier.exported.name === 'default') {
+				styles.add('default');
+				continue;
+			}
+
+			styles.add('named');
+			continue;
+		}
+	}
+
+	return [...styles];
+};
+
 const getActualAssignmentTargetImportStyles = assignmentTarget => {
 	if (assignmentTarget.type === 'Identifier') {
 		return ['namespace'];
@@ -124,6 +148,7 @@ const create = context => {
 			extendDefaultStyles = true,
 			checkImport = true,
 			checkDynamicImport = true,
+			checkExportFrom = false,
 			checkRequire = true
 		} = {}
 	] = context.options;
@@ -219,6 +244,30 @@ const create = context => {
 		};
 	}
 
+	if (checkExportFrom) {
+		visitor = {
+			...visitor,
+
+			ExportAllDeclaration(node) {
+				const moduleName = getStringIfConstant(node.source, context.getScope());
+
+				const allowedImportStyles = styles.get(moduleName);
+				const actualImportStyles = ['namespace'];
+
+				report(node, moduleName, actualImportStyles, allowedImportStyles);
+			},
+
+			ExportNamedDeclaration(node) {
+				const moduleName = getStringIfConstant(node.source, context.getScope());
+
+				const allowedImportStyles = styles.get(moduleName);
+				const actualImportStyles = getActualExportDeclarationStyles(node);
+
+				report(node, moduleName, actualImportStyles, allowedImportStyles);
+			}
+		};
+	}
+
 	if (checkRequire) {
 		visitor = {
 			...visitor,
@@ -261,6 +310,9 @@ const schema = [
 			checkDynamicImport: {
 				type: 'boolean'
 			},
+			checkExportFrom: {
+				type: 'boolean'
+			},
 			checkRequire: {
 				type: 'boolean'
 			},

diff --git a/test/import-style.js b/test/import-style.js
@@ -11,6 +11,7 @@ const ruleTester = avaRuleTester(test, {
 });
 
 const options = {
+	checkExportFrom: true,
 	styles: {
 		unassigned: {
 			unassigned: true
@@ -77,6 +78,7 @@ ruleTester.run('import-style', rule, {
 		'require(\'unassigned\')',
 		'import \'unassigned\'',
 		'import(\'unassigned\')',
+		'export {} from \'unassigned\'',
 
 		'const x = require(\'default\')',
 		'const {default: x} = require(\'default\')',
@@ -86,6 +88,7 @@ ruleTester.run('import-style', rule, {
 				const {default: x} = await import('default');
 			}
 		`,
+		'export {default} from \'default\'',
 
 		'const x = require(\'namespace\')',
 		'import * as x from \'namespace\'',
@@ -94,6 +97,7 @@ ruleTester.run('import-style', rule, {
 				const x = await import('namespace');
 			}
 		`,
+		'export * from \'namespace\'',
 
 		'const {x} = require(\'named\')',
 		'const {x: y} = require(\'named\')',
@@ -109,6 +113,8 @@ ruleTester.run('import-style', rule, {
 				const {x: y} = await import('named');
 			}
 		`,
+		'export {x} from \'named\'',
+		'export {x as y} from \'named\'',
 
 		{
 			code: 'import {inspect} from \'util\'',
@@ -264,6 +270,22 @@ ruleTester.run('import-style', rule, {
 			`,
 			errors: [unassignedError]
 		},
+		{
+			code: 'export * from \'unassigned\'',
+			errors: [unassignedError]
+		},
+		{
+			code: 'export {x} from \'unassigned\'',
+			errors: [unassignedError]
+		},
+		{
+			code: 'export {x as y} from \'unassigned\'',
+			errors: [unassignedError]
+		},
+		{
+			code: 'export {default} from \'unassigned\'',
+			errors: [unassignedError]
+		},
 
 		{
 			code: 'require(\'default\')',
@@ -321,6 +343,18 @@ ruleTester.run('import-style', rule, {
 			`,
 			errors: [defaultError]
 		},
+		{
+			code: 'export * from \'default\'',
+			errors: [defaultError]
+		},
+		{
+			code: 'export {x} from \'default\'',
+			errors: [defaultError]
+		},
+		{
+			code: 'export {x as y} from \'default\'',
+			errors: [defaultError]
+		},
 
 		{
 			code: 'require(\'namespace\')',
@@ -374,6 +408,18 @@ ruleTester.run('import-style', rule, {
 			`,
 			errors: [namespaceError]
 		},
+		{
+			code: 'export {x} from \'namespace\'',
+			errors: [namespaceError]
+		},
+		{
+			code: 'export {x as y} from \'namespace\'',
+			errors: [namespaceError]
+		},
+		{
+			code: 'export {default} from \'namespace\'',
+			errors: [namespaceError]
+		},
 
 		{
 			code: 'require(\'named\')',
@@ -419,6 +465,14 @@ ruleTester.run('import-style', rule, {
 			`,
 			errors: [namedError]
 		},
+		{
+			code: 'export * from \'named\'',
+			errors: [namedError]
+		},
+		{
+			code: 'export {default} from \'named\'',
+			errors: [namedError]
+		},
 
 		{
 			code: 'import util, {inspect} from \'named\'',