[Fix] display-name: fix false positive for HOF returning only nulls and literals

Author: golopot

lib/util/Components.js

@@ -503,7 +503,6 @@ function componentRule(rule, context) {
         if (
           (node.parent.type === 'ReturnStatement' || (node.parent.type === 'ArrowFunctionExpression' && node.parent.expression))
           && !utils.isReturningJSX(node)
-          && !utils.isReturningOnlyNull(node)
         ) {
           return undefined;
         }

tests/lib/rules/display-name.js

@@ -556,6 +556,17 @@ ruleTester.run('display-name', rule, {
         }
       `,
     },
+    {
+      // issue #3300
+      code: `
+        const f = (a) => () => {
+          if (a) {
+            return null;
+          }
+          return 1;
+        };
+      `,
+    },
     {
       code: `
         class Test {
@@ -1169,33 +1180,5 @@ ruleTester.run('display-name', rule, {
         },
       ],
     },
-    {
-      code: `
-        Demo = () => () => null;
-      `,
-      errors: [{ messageId: 'noDisplayName' }],
-    },
-    {
-      code: `
-        demo = {
-          Property: () => () => null
-        }
-      `,
-      errors: [{ messageId: 'noDisplayName' }],
-    },
-    {
-      code: `
-        Demo = function() {return function() {return null;};};
-      `,
-      errors: [{ messageId: 'noDisplayName' }],
-    },
-    {
-      code: `
-        demo = {
-          Property: function() {return function() {return null;};}
-        }
-      `,
-      errors: [{ messageId: 'noDisplayName' }],
-    },
   ]),
 });

tests/lib/rules/no-this-in-sfc.js

@@ -275,58 +275,5 @@ ruleTester.run('no-this-in-sfc', rule, {
         { messageId: 'noThisInSFC' },
       ],
     },
-    {
-      code: `
-        class Foo {
-          bar() {
-            return () => {
-              this.something();
-              return null;
-            }
-          }
-        }
-      `,
-      errors: [{ messageId: 'noThisInSFC' }],
-    },
-    {
-      code: `
-        class Foo {
-          bar = () => () => {
-            this.something();
-            return null;
-          };
-        }
-      `,
-      features: ['class fields', 'no-ts-old'], // TODO: FIXME: remove `no-ts-old` and fix
-      errors: [{ messageId: 'noThisInSFC' }],
-    },
-    {
-      code: `
-        class Foo {
-          bar() {
-            function Bar(){
-              return () => {
-                this.something();
-                return null;
-              }
-            }
-          }
-        }
-      `,
-      errors: [{ messageId: 'noThisInSFC' }],
-    },
-    {
-      code: `
-        class Foo {
-          bar() {
-            () => () => {
-              this.something();
-              return null;
-            };
-          }
-        }
-      `,
-      errors: [{ messageId: 'noThisInSFC' }],
-    },
   ]),
 });