Add suggestion for 'prefer-single-boolean-return'

README.md

@@ -43,7 +43,7 @@ Code Smells, or maintainability issues, are raised for places of code which migh
 * "catch" clauses should do more than rethrow ([`no-useless-catch`])
 * Local variables should not be declared and then immediately returned or thrown ([`prefer-immediate-return`]) (:wrench: *fixable*)
 * Object literal syntax should be used ([`prefer-object-literal`])
-* Return of boolean expressions should not be wrapped into an "if-then-else" statement ([`prefer-single-boolean-return`])
+* Return of boolean expressions should not be wrapped into an "if-then-else" statement ([`prefer-single-boolean-return`]) (:wrench: *fixable*)
 * A "while" loop should be used instead of a "for" loop ([`prefer-while`]) (:wrench: *fixable*)
 
 [`cognitive-complexity`]: ./docs/rules/cognitive-complexity.md

docs/rules/prefer-single-boolean-return.md

@@ -1,5 +1,7 @@
 # prefer-single-boolean-return
 
+:wrench: *fixable*
+
 Return of boolean literal statements wrapped into `if-then-else` flow should be simplified.
 
 ## Noncompliant Code Example

src/rules/prefer-single-boolean-return.ts

@@ -31,9 +31,11 @@ const rule: TSESLint.RuleModule<string, string[]> = {
   meta: {
     messages: {
       replaceIfThenElseByReturn: 'Replace this if-then-else flow by a single return statement.',
+      suggestIfThenElseReplacement: 'Replace with single return statement',
     },
     schema: [],
     type: 'suggestion',
+    hasSuggestions: true,
     docs: {
       description:
         'Return of boolean expressions should not be wrapped into an "if-then-else" statement',
@@ -53,6 +55,7 @@ const rule: TSESLint.RuleModule<string, string[]> = {
           context.report({
             messageId: 'replaceIfThenElseByReturn',
             node,
+            suggest: getSuggestion(node),
           });
         }
       },
@@ -91,6 +94,26 @@ const rule: TSESLint.RuleModule<string, string[]> = {
       // `statement.argument` can be `null`, replace it with `undefined` in this case
       return isReturnStatement(statement) && isBooleanLiteral(statement.argument || undefined);
     }
+
+    function getSuggestion(ifStmt: TSESTree.IfStatement): TSESLint.ReportSuggestionArray<string> {
+      return [
+        {
+          messageId: 'suggestIfThenElseReplacement',
+          fix: fixer => {
+            const singleReturn = `return ${context.getSourceCode().getText(ifStmt.test)};`;
+            if (ifStmt.alternate) {
+              return fixer.replaceText(ifStmt, singleReturn);
+            } else {
+              const parent = ifStmt.parent as TSESTree.BlockStatement;
+              const ifStmtIndex = parent.body.findIndex(stmt => stmt === ifStmt);
+              const returnStmt = parent.body[ifStmtIndex + 1];
+              const range: [number, number] = [ifStmt.range[0], returnStmt.range[1]];
+              return fixer.replaceTextRange(range, singleReturn);
+            }
+          },
+        },
+      ];
+    }
   },
 };
 

tests/rules/prefer-single-boolean-return.test.ts

@@ -227,5 +227,64 @@ ruleTester.run('prefer-single-boolean-return', rule, {
         },
       ],
     },
+    {
+      code: `
+function foo() {
+  if (bar()) {
+    if (baz()) {
+      return true;
+    } else {
+      return false;
+    }
+  }
+  return qux();
+}`,
+      errors: [
+        {
+          messageId: 'replaceIfThenElseByReturn',
+          suggestions: [
+            {
+              messageId: 'suggestIfThenElseReplacement',
+              output: `
+function foo() {
+  if (bar()) {
+    return baz();
+  }
+  return qux();
+}`,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+function foo() {
+  if (bar()) {
+    if (baz()) {
+      return true;
+    }
+    return false;
+  }
+  return qux();
+}`,
+      errors: [
+        {
+          messageId: 'replaceIfThenElseByReturn',
+          suggestions: [
+            {
+              messageId: 'suggestIfThenElseReplacement',
+              output: `
+function foo() {
+  if (bar()) {
+    return baz();
+  }
+  return qux();
+}`,
+            },
+          ],
+        },
+      ],
+    },
   ],
 });