From f4e3f1b3db2aa33cf3211ff64e46d696a324485a Mon Sep 17 00:00:00 2001
From: Sharmila <sharmila.jesupaul@airbnb.com>
Date: Wed, 17 Jul 2019 10:47:23 -0700
Subject: [PATCH] prefer-default-export: don't warn on TypeAlias &
 TSTypeAliasDeclaration

Fixes #1332.
---
 src/rules/prefer-default-export.js       |  9 +++-
 tests/src/rules/prefer-default-export.js | 67 +++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/src/rules/prefer-default-export.js b/src/rules/prefer-default-export.js
index 0e31346f3..01b8d8be0 100644
--- a/src/rules/prefer-default-export.js
+++ b/src/rules/prefer-default-export.js
@@ -47,9 +47,16 @@ module.exports = {
         // if there are specifiers, node.declaration should be null
         if (!node.declaration) return
 
-        // don't count flow types exports
+        // don't warn on single type aliases or declarations
         if (node.exportKind === 'type') return
 
+        if (
+          node.declaration.type === 'TSTypeAliasDeclaration' ||
+          node.declaration.type === 'TypeAlias'
+        ) {
+          return
+        }
+
         if (node.declaration.declarations) {
           node.declaration.declarations.forEach(function(declaration) {
             captureDeclaration(declaration.id)
diff --git a/tests/src/rules/prefer-default-export.js b/tests/src/rules/prefer-default-export.js
index 1d670a02f..55e739d98 100644
--- a/tests/src/rules/prefer-default-export.js
+++ b/tests/src/rules/prefer-default-export.js
@@ -1,6 +1,8 @@
 import { test } from '../utils'
 
 import { RuleTester } from 'eslint'
+import eslintPkg from 'eslint/package.json'
+import semver from 'semver'
 
 const ruleTester = new RuleTester()
     , rule = require('rules/prefer-default-export')
@@ -83,7 +85,6 @@ ruleTester.run('prefer-default-export', rule, {
       code: 'export { a, b } from "foo.js"',
       parser: require.resolve('babel-eslint'),
     }),
-
     // ...SYNTAX_CASES,
   ],
   invalid: [
@@ -129,4 +130,66 @@ ruleTester.run('prefer-default-export', rule, {
       }],
     }),
   ],
-})
+});
+
+context('Typescript', function() {
+  // Typescript
+  const parsers = [require.resolve('babel-eslint')];
+
+  if (semver.satisfies(eslintPkg.version, '>=4.0.0 <6.0.0')) {
+    parsers.push(require.resolve('typescript-eslint-parser'));
+  }
+
+  if (semver.satisfies(eslintPkg.version, '>5.0.0')) {
+    parsers.push(require.resolve('@typescript-eslint/parser'));
+  }
+
+  parsers.forEach((parser) => {
+    const parserConfig = {
+      parser: parser,
+      settings: {
+        'import/parsers': { [parser]: ['.ts'] },
+        'import/resolver': { 'eslint-import-resolver-typescript': true },
+      },
+    };
+
+    ruleTester.run('prefer-default-export', rule, {
+      valid: [
+        // Exporting types
+        test(
+          {
+            code: `
+        export type foo = string;
+        export type bar = number;`,
+            parser,
+          },
+          parserConfig,
+        ),
+        test(
+          {
+            code: `
+        export type foo = string;
+        export type bar = number;`,
+            parser,
+          },
+          parserConfig,
+        ),
+        test(
+          {
+            code: 'export type foo = string',
+            parser,
+          },
+          parserConfig,
+        ),
+        test(
+          {
+            code: 'export type foo = string',
+            parser,
+          },
+          parserConfig,
+        ),
+      ],
+      invalid: [],
+    });
+  });
+});