add more docs and return to foo bar instead of x y as variable names

docs/rules/prefer-default-export.md

@@ -24,10 +24,28 @@ export const foo = 'foo';
 const bar = 'bar';
 export default 'bar';
 ```
+
 ```javascript
 // good2.js
 
 // There is more thank one named exports in the module.
 export const foo = 'foo';
 export const bar = 'bar';
 ```
+
+```javascript
+// good3.js
+
+// There is more thank one named exports in the module
+const foo = 'foo';
+const bar = 'bar';
+export { foo, bar }
+```
+
+```javascript
+// good4.js
+
+// There is a default export.
+const foo = 'foo';
+export { foo as default }
+```

tests/src/rules/prefer-default-export.js

@@ -9,36 +9,36 @@ ruleTester.run('prefer-default-export', rule, {
   valid: [
     test({
       code: `
-        export const x = 'x';
-        export const y = 'y';`,
+        export const foo = 'foo';
+        export const bar = 'bar';`,
       }),
     test({
       code: `
-        export const x = 'x';
-        export default y;`,
+        export const foo = 'foo';
+        export default bar;`,
       }),
     test({
       code: `
-        export { x, y }`,
+        export { foo, bar }`,
       }),
     test({
       code: `
-        export { z as default }`,
+        export { foo as default }`,
       }),
   ],
   invalid: [
     test({
       code: `
-        export const x = 'x';`,
+        export const foo = 'foo';`,
       errors: [{
         ruleId: 'ExportNamedDeclaration',
         message: 'Prefer default export.',
       }],
     }),
     test({
       code: `
-        const x = 'x';
-        export { x };`,
+        const foo = 'foo';
+        export { foo };`,
       errors: [{
         ruleId: 'ExportNamedDeclaration',
         message: 'Prefer default export.',