feat: add autofix to no-duplicate-imports rule (eslint#216)

* feat: add autofix to no-duplicate-imports rule

* add test for non-adjacent duplicate @import statements

Author: thecalamiity

src/rules/no-duplicate-imports.js

@@ -24,6 +24,8 @@ export default {
 	meta: {
 		type: "problem",
 
+		fixable: "code",
+
 		docs: {
 			description: "Disallow duplicate @import rules",
 			recommended: true,
@@ -36,6 +38,7 @@ export default {
 	},
 
 	create(context) {
+		const { sourceCode } = context;
 		const imports = new Set();
 
 		return {
@@ -47,6 +50,13 @@ export default {
 						loc: node.loc,
 						messageId: "duplicateImport",
 						data: { url },
+						fix(fixer) {
+							const [start, end] = sourceCode.getRange(node);
+							// Remove the node, and also remove a following newline if present
+							const removeEnd =
+								sourceCode.text[end] === "\n" ? end + 1 : end;
+							return fixer.removeRange([start, removeEnd]);
+						},
 					});
 				} else {
 					imports.add(url);

tests/rules/no-duplicate-imports.test.js

@@ -31,6 +31,7 @@ ruleTester.run("no-duplicate-imports", rule, {
 	invalid: [
 		{
 			code: "@import url('x.css');\n@import url('x.css');",
+			output: "@import url('x.css');\n",
 			errors: [
 				{
 					messageId: "duplicateImport",
@@ -42,8 +43,37 @@ ruleTester.run("no-duplicate-imports", rule, {
 				},
 			],
 		},
+		{
+			code: "@import url('x.css');@import url('x.css');",
+			output: "@import url('x.css');",
+			errors: [
+				{
+					messageId: "duplicateImport",
+					data: { url: "x.css" },
+					line: 1,
+					column: 22,
+					endLine: 1,
+					endColumn: 43,
+				},
+			],
+		},
+		{
+			code: "@import url('x.css');@import url('x.css');@import url('y.css')",
+			output: "@import url('x.css');@import url('y.css')",
+			errors: [
+				{
+					messageId: "duplicateImport",
+					data: { url: "x.css" },
+					line: 1,
+					column: 22,
+					endLine: 1,
+					endColumn: 43,
+				},
+			],
+		},
 		{
 			code: "@import url('x.css');\n@import 'x.css';",
+			output: "@import url('x.css');\n",
 			errors: [
 				{
 					messageId: "duplicateImport",
@@ -57,6 +87,7 @@ ruleTester.run("no-duplicate-imports", rule, {
 		},
 		{
 			code: "@import url('x.css');\n@import 'x.css';\n@import 'x.css';",
+			output: "@import url('x.css');\n@import 'x.css';",
 			errors: [
 				{
 					messageId: "duplicateImport",
@@ -78,6 +109,7 @@ ruleTester.run("no-duplicate-imports", rule, {
 		},
 		{
 			code: "@import url('x.css');\n@import 'x.css';\n@import url('y.css');\n@import 'y.css';",
+			output: "@import url('x.css');\n@import url('y.css');\n",
 			errors: [
 				{
 					messageId: "duplicateImport",
@@ -97,5 +129,33 @@ ruleTester.run("no-duplicate-imports", rule, {
 				},
 			],
 		},
+		{
+			code: "@import url('a.css');\n@import url('b.css');\n@import url('c.css');\n@import url('a.css');\n@import url('d.css');",
+			output: "@import url('a.css');\n@import url('b.css');\n@import url('c.css');\n@import url('d.css');",
+			errors: [
+				{
+					messageId: "duplicateImport",
+					data: { url: "a.css" },
+					line: 4,
+					column: 1,
+					endLine: 4,
+					endColumn: 22,
+				},
+			],
+		},
+		{
+			code: "@import url('a.css');\n@import url('b.css');\n/* comment */\n@import 'a.css';",
+			output: "@import url('a.css');\n@import url('b.css');\n/* comment */\n",
+			errors: [
+				{
+					messageId: "duplicateImport",
+					data: { url: "a.css" },
+					line: 4,
+					column: 1,
+					endLine: 4,
+					endColumn: 17,
+				},
+			],
+		},
 	],
 });