prefer-string-slice: Keep optional chaining in autofix (#1085)

Author: noftaly

rules/prefer-string-slice.js

@@ -104,8 +104,10 @@ const create = context => {
 
 			if (sliceArguments) {
 				const objectText = getNodeText(objectNode);
+				const optionalMemberSuffix = node.callee.optional ? '?' : '';
+				const optionalCallSuffix = node.optional ? '?.' : '';
 
-				problem.fix = fixer => fixer.replaceText(node, `${objectText}.slice(${sliceArguments.join(', ')})`);
+				problem.fix = fixer => fixer.replaceText(node, `${objectText}${optionalMemberSuffix}.slice${optionalCallSuffix}(${sliceArguments.join(', ')})`);
 			}
 
 			context.report(problem);
@@ -158,7 +160,10 @@ const create = context => {
 
 			if (sliceArguments) {
 				const objectText = getNodeText(objectNode);
-				problem.fix = fixer => fixer.replaceText(node, `${objectText}.slice(${sliceArguments.join(', ')})`);
+				const optionalMemberSuffix = node.callee.optional ? '?' : '';
+				const optionalCallSuffix = node.optional ? '?.' : '';
+
+				problem.fix = fixer => fixer.replaceText(node, `${objectText}${optionalMemberSuffix}.slice${optionalCallSuffix}(${sliceArguments.join(', ')})`);
 			}
 
 			context.report(problem);

test/prefer-string-slice.js

@@ -23,6 +23,9 @@ test({
 		'foo.slice()',
 		'foo.slice(0)',
 		'foo.slice(1, 2)',
+		'foo?.slice(1, 2)',
+		'foo?.slice?.(1, 2)',
+		'foo?.bar.baz.slice(1, 2)',
 		'foo.slice(-3, -2)'
 	],
 
@@ -32,6 +35,46 @@ test({
 			output: 'foo.slice()',
 			errors: errorsSubstr
 		},
+		{
+			code: 'foo?.substr()',
+			output: 'foo?.slice()',
+			errors: errorsSubstr
+		},
+		{
+			code: 'foo.bar?.substring()',
+			output: 'foo.bar?.slice()',
+			errors: errorsSubstring
+		},
+		{
+			code: 'foo?.[0]?.substring()',
+			output: 'foo?.[0]?.slice()',
+			errors: errorsSubstring
+		},
+		{
+			code: 'foo.bar.substr?.()',
+			output: 'foo.bar.slice?.()',
+			errors: errorsSubstr
+		},
+		{
+			code: 'foo.bar?.substring?.()',
+			output: 'foo.bar?.slice?.()',
+			errors: errorsSubstring
+		},
+		{
+			code: 'foo.bar?.baz?.substr()',
+			output: 'foo.bar?.baz?.slice()',
+			errors: errorsSubstr
+		},
+		{
+			code: 'foo.bar?.baz.substring()',
+			output: 'foo.bar?.baz.slice()',
+			errors: errorsSubstring
+		},
+		{
+			code: 'foo.bar.baz?.substr()',
+			output: 'foo.bar.baz?.slice()',
+			errors: errorsSubstr
+		},
 		{
 			code: '"foo".substr()',
 			output: '"foo".slice()',