From 800268435a8465660f8569f7ba30a94c2b1f75a1 Mon Sep 17 00:00:00 2001
From: Fathy Boundjadj <fathy.boundjadj@gmail.com>
Date: Tue, 20 Mar 2018 03:14:40 +0100
Subject: [PATCH] Set TypeScript option esModuleInterop to true by default
 (#971)

---
 package.json                                  |  2 +-
 src/assets/TypeScriptAsset.js                 |  6 +++++-
 .../typescript-interop/commonjs-module.js     |  1 +
 test/integration/typescript-interop/index.ts  |  3 +++
 test/typescript.js                            | 20 +++++++++++++++++++
 yarn.lock                                     |  2 +-
 6 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 test/integration/typescript-interop/commonjs-module.js
 create mode 100644 test/integration/typescript-interop/index.ts

diff --git a/package.json b/package.json
index d79747721be..6c96f7c7c5c 100644
--- a/package.json
+++ b/package.json
@@ -88,7 +88,7 @@
     "sinon": "^4.2.2",
     "sourcemap-validator": "^1.0.6",
     "stylus": "^0.54.5",
-    "typescript": "^2.6.2"
+    "typescript": "^2.7.0"
   },
   "scripts": {
     "test": "cross-env NODE_ENV=test mocha",
diff --git a/src/assets/TypeScriptAsset.js b/src/assets/TypeScriptAsset.js
index e4b3b2a740f..ef41d84d522 100644
--- a/src/assets/TypeScriptAsset.js
+++ b/src/assets/TypeScriptAsset.js
@@ -8,7 +8,11 @@ class TypeScriptAsset extends JSAsset {
     let transpilerOptions = {
       compilerOptions: {
         module: typescript.ModuleKind.CommonJS,
-        jsx: typescript.JsxEmit.Preserve
+        jsx: typescript.JsxEmit.Preserve,
+
+        // it brings the generated output from TypeScript closer to that generated by Babel
+        // see https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-7.html
+        esModuleInterop: true
       },
       fileName: this.relativeName
     };
diff --git a/test/integration/typescript-interop/commonjs-module.js b/test/integration/typescript-interop/commonjs-module.js
new file mode 100644
index 00000000000..21503057ff6
--- /dev/null
+++ b/test/integration/typescript-interop/commonjs-module.js
@@ -0,0 +1 @@
+module.exports = () => 'test passed'
diff --git a/test/integration/typescript-interop/index.ts b/test/integration/typescript-interop/index.ts
new file mode 100644
index 00000000000..91be0f05072
--- /dev/null
+++ b/test/integration/typescript-interop/index.ts
@@ -0,0 +1,3 @@
+import testModule from './commonjs-module'
+
+export const test = testModule
diff --git a/test/typescript.js b/test/typescript.js
index a0cb3e63695..56463519fd9 100644
--- a/test/typescript.js
+++ b/test/typescript.js
@@ -106,4 +106,24 @@ describe('typescript', function() {
     let file = fs.readFileSync(__dirname + '/dist/index.js', 'utf8');
     assert(file.includes('React.createElement("div"'));
   });
+
+  it('should use esModuleInterop by default', async function() {
+    let b = await bundle(
+      __dirname + '/integration/typescript-interop/index.ts'
+    );
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.ts', 'commonjs-module.js'],
+      childBundles: [
+        {
+          type: 'map'
+        }
+      ]
+    });
+
+    let output = run(b);
+    assert.equal(typeof output.test, 'function');
+    assert.equal(output.test(), 'test passed');
+  });
 });
diff --git a/yarn.lock b/yarn.lock
index 8f6ce18f06d..6257320bda4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6087,7 +6087,7 @@ typedarray@^0.0.6:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
 
-typescript@^2.6.2:
+typescript@^2.7.0:
   version "2.7.2"
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.7.2.tgz#2d615a1ef4aee4f574425cdff7026edf81919836"