chore: handle map callbacks

Author: akulsr0

lib/rules/no-render-return-undefined.js

@@ -66,8 +66,23 @@ module.exports = {
           return possibleReturnValue;
         }
         case 'CallExpression': {
+          if (returnNode.callee.type === 'MemberExpression') {
+            const calleeObjName = returnNode.callee.object.name;
+            const calleePropertyName = returnNode.callee.property.name;
+            const calleeObjNode = variables.find((item) => item && item.name === calleeObjName);
+            const isCalleeObjArray = calleeObjNode.defs[0].node.init.type === 'ArrayExpression';
+            const isMapCall = isCalleeObjArray && calleePropertyName === 'map';
+            if (isMapCall) {
+              const mapCallback = returnNode.arguments[0];
+              const mapReturnStatement = mapCallback.body.type === 'BlockStatement'
+                  && astUtil.findReturnStatement(returnNode.arguments[0]);
+              const mapReturnNode = (mapReturnStatement && mapReturnStatement.argument) || mapCallback.body;
+              // console.log('DEBUG', mapReturnNode);
+              return getReturnValue(mapReturnNode);
+            }
+          }
           const calleeName = returnNode.callee.name;
-          const calleeNode = variableUtil.variablesInScope(context).find((item) => item.name === calleeName);
+          const calleeNode = variables.find((item) => item && item.name === calleeName);
           const calleeDefinitionNode = calleeNode && calleeNode.defs && calleeNode.defs[0] && calleeNode.defs[0].node;
           const calleeReturnStatement = astUtil.findReturnStatement(calleeDefinitionNode);
           const calleeReturnNode = (calleeReturnStatement && calleeReturnStatement.argument)
@@ -102,7 +117,7 @@ module.exports = {
     };
 
     const handleFunctionalComponents = (node) => {
-      const fnName = (node.id && node.id.name) || node.parent.id.name;
+      const fnName = (node.id && node.id.name) || (node.parent.id && node.parent.id.name);
 
       // Considering functions starting with Uppercase letters are react components
       const isReactComponent = isFirstLetterCapitalized(fnName);

tests/lib/rules/no-render-return-undefined.js

@@ -417,6 +417,42 @@ ruleTester.run('no-render-return-undefined', rule, {
             }
         `,
     },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return data.map(name => <h1>{name}</h1>);
+        }
+      `,
+    },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return data.map(name => {
+            return <h1>{name}</h1>;
+          });
+        }
+      `,
+    },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return cond && data.map(name => {
+            return <h1>{name}</h1>;
+          });
+        }
+      `,
+    },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return cond ? data.map(name => <h1>{name}</h1>) : null;
+        }
+      `,
+    },
   ]),
 
   // Invalid Cases
@@ -845,5 +881,48 @@ ruleTester.run('no-render-return-undefined', rule, {
         `,
       errors: [{ messageId: 'returnsUndefined' }],
     },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return cond ? data.map(name => <h1>{name}</h1>) : undefined;
+        }
+      `,
+      errors: [{ messageId: 'returnsUndefined' }],
+    },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return data.map(name => {
+            if(cond) return <h1>{name}</h1>;
+          });
+        }
+      `,
+      errors: [{ messageId: 'returnsUndefined' }],
+    },
+    {
+      code: `
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          if(cond) {
+            return data.map(name => <h1>{name}</h1>);
+          }
+        }
+      `,
+      errors: [{ messageId: 'returnsUndefined' }],
+    },
+    {
+      code: `
+        let x;
+        const data = ['John', 'Ram' , 'Akul'];
+        function App() {
+          return cond ? data.map(name => {
+            return <h1>{name}</h1>;
+          }) : x;
+        }
+      `,
+      errors: [{ messageId: 'returnsUndefined' }],
+    },
   ]),
 });