From c57f1e0801462ce0691416fb90d513117147c689 Mon Sep 17 00:00:00 2001
From: Alexandre Breteau <contact@seldszar.fr>
Date: Fri, 19 Oct 2018 01:08:11 +0200
Subject: [PATCH] fix(gatsby): ignore `__esModule` property when resolving
 module exports (#9226)

---
 .../src/bootstrap/__tests__/resolve-module-exports.js    | 9 +++++++++
 packages/gatsby/src/bootstrap/resolve-module-exports.js  | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js b/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
index 25898b9d13c0d..9a253157d4a4b 100644
--- a/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
+++ b/packages/gatsby/src/bootstrap/__tests__/resolve-module-exports.js
@@ -107,6 +107,10 @@ describe(`Resolve module exports`, () => {
         return createElement(ReplaceComponentRenderer, { ...props, loader })
       }
     `,
+    "/esmodule/export": `
+      exports.__esModule = true;
+      exports.foo = '';
+    `,
   }
 
   beforeEach(() => {
@@ -165,4 +169,9 @@ describe(`Resolve module exports`, () => {
     const result = resolveModuleExports(`/realistic/export`, resolver)
     expect(result).toEqual([`replaceHistory`, `replaceComponentRenderer`])
   })
+
+  it(`Ignores exports.__esModule`, () => {
+    const result = resolveModuleExports(`/esmodule/export`, resolver)
+    expect(result).toEqual([`foo`])
+  })
 })
diff --git a/packages/gatsby/src/bootstrap/resolve-module-exports.js b/packages/gatsby/src/bootstrap/resolve-module-exports.js
index 9c3704001a5f0..30057db5361fe 100644
--- a/packages/gatsby/src/bootstrap/resolve-module-exports.js
+++ b/packages/gatsby/src/bootstrap/resolve-module-exports.js
@@ -75,6 +75,9 @@ module.exports = (modulePath, resolver = require.resolve) => {
 
       if (nodeLeft.type !== `MemberExpression`) return
 
+      // ignore marker property `__esModule`
+      if (get(nodeLeft, `property.name`) === `__esModule`) return
+
       // get foo from `exports.foo = bar`
       if (get(nodeLeft, `object.name`) === `exports`) {
         isCommonJS = true