FN prefer-immediate-return: consider hoisted variables (#83)

Author: andrea-guarino-sonarsource

ruling/snapshots/prefer-immediate-return

@@ -17,8 +17,8 @@ src/jest/packages/jest-resolve/src/index.js: 378
 src/react-native/jest/mockComponent.js: 13
 src/react-native/Libraries/Animated/src/nodes/AnimatedInterpolation.js: 359
 src/react-native/Libraries/Components/ScrollResponder.js: 385
-src/react-native/Libraries/Renderer/ReactFabric-dev.js: 3139,10554,10585,13532
-src/react-native/Libraries/Renderer/ReactNativeRenderer-dev.js: 3589,10924,10955
+src/react-native/Libraries/Renderer/ReactFabric-dev.js: 3139,10554,10585,12291,13532
+src/react-native/Libraries/Renderer/ReactNativeRenderer-dev.js: 3589,10924,10955,12661
 src/react-native/local-cli/bundle/assetPathUtils.js: 52
 src/react-native/local-cli/util/PackageManager.js: 40
 src/react-native/RNTester/js/ScrollViewSimpleExample.js: 63

src/rules/prefer-immediate-return.ts

@@ -46,7 +46,7 @@ const rule: Rule.RuleModule = {
         const declaredIdentifier = getOnlyDeclaredVariable(lastButOne);
 
         if (returnedIdentifier && declaredIdentifier) {
-          const sameVariable = context.getScope().variables.find(variable => {
+          const sameVariable = getVariables(context).find(variable => {
             return (
               variable.references.find(ref => ref.identifier === returnedIdentifier) !== undefined &&
               variable.references.find(ref => ref.identifier === declaredIdentifier.id) !== undefined
@@ -111,6 +111,15 @@ const rule: Rule.RuleModule = {
       const action = isReturnStatement(node) ? "return" : "throw";
       return `Immediately ${action} this expression instead of assigning it to the temporary variable "${variable}".`;
     }
+
+    function getVariables(context: Rule.RuleContext) {
+      const { variableScope, variables: currentScopeVariables } = context.getScope();
+      if (variableScope === context.getScope()) {
+        return currentScopeVariables;
+      } else {
+        return currentScopeVariables.concat(variableScope.variables);
+      }
+    }
   },
 };
 

tests/rules/prefer-immediate-return.test.ts

@@ -303,5 +303,21 @@ ruleTester.run("prefer-immediate-return", rule, {
           return 42
         }`,
     },
+    {
+      // hoisted variables
+      code: `
+      function foo() {
+        if (cond) {
+          var x = 42;
+          return x;
+      }
+      }
+      `,
+      errors: [
+        {
+          message: 'Immediately return this expression instead of assigning it to the temporary variable "x".',
+        },
+      ],
+    },
   ],
 });