From 8e2aa8299197afffa441c48c441c7842bbce7e43 Mon Sep 17 00:00:00 2001
From: Henry Zhu <hi@henryzoo.com>
Date: Tue, 6 Dec 2016 14:31:16 -0500
Subject: [PATCH] also transform 'core-js'

---
 experimental/babel-preset-env/README.md              |  9 +++++++++
 .../src/transformPolyfillRequirePlugin.js            | 12 +++++++-----
 .../test/fixtures/preset-options/core-js/actual.js   |  1 +
 .../test/fixtures/preset-options/core-js/expected.js |  2 ++
 .../fixtures/preset-options/core-js/options.json     | 11 +++++++++++
 .../fixtures/preset-options/no-transform/actual.js   |  2 ++
 .../fixtures/preset-options/no-transform/expected.js |  2 ++
 .../preset-options/no-transform/options.json         | 11 +++++++++++
 8 files changed, 45 insertions(+), 5 deletions(-)
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/core-js/actual.js
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/core-js/expected.js
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/core-js/options.json
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/no-transform/actual.js
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/no-transform/expected.js
 create mode 100644 experimental/babel-preset-env/test/fixtures/preset-options/no-transform/options.json

diff --git a/experimental/babel-preset-env/README.md b/experimental/babel-preset-env/README.md
index 6a2f4ee669..704bb2f964 100644
--- a/experimental/babel-preset-env/README.md
+++ b/experimental/babel-preset-env/README.md
@@ -126,6 +126,9 @@ Defaults to `false`.
 
 A way to apply `babel-preset-env` for polyfills (via "babel-polyfill").
 
+> NOTE: This does not currently polyfill experimental/stage-x built-ins like the regular "babel-polyfill" does.
+> This will only work with npm >= 3 (which should be used with Babel 6 anyway)
+
 ```
 npm install babel-polyfill --save
 ```
@@ -151,6 +154,12 @@ import "core-js/modules/es6.symbol.species";
 import "core-js/modules/es6.array.from";
 ```
 
+> This will also work for "core-js" directly (`import "core-js";`)
+
+```
+npm install core-js --save
+```
+
 ---
 
 ## Examples
diff --git a/experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js b/experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js
index 6412dbe5af..16af0c7be1 100644
--- a/experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js
+++ b/experimental/babel-preset-env/src/transformPolyfillRequirePlugin.js
@@ -1,4 +1,6 @@
-const polyfillSource = "babel-polyfill";
+function isPolyfillSource(value) {
+  return value === "babel-polyfill" || value === "core-js";
+}
 
 export default function ({ types: t }) {
   function createImportDeclaration(polyfill) {
@@ -18,20 +20,20 @@ export default function ({ types: t }) {
     );
   }
 
-  function isRequire(path, source) {
+  function isRequire(path) {
     return t.isExpressionStatement(path.node) &&
       t.isCallExpression(path.node.expression) &&
       t.isIdentifier(path.node.expression.callee) &&
       path.node.expression.callee.name === "require" &&
       path.node.expression.arguments.length === 1 &&
       t.isStringLiteral(path.node.expression.arguments[0]) &&
-      path.node.expression.arguments[0].value === source;
+      isPolyfillSource(path.node.expression.arguments[0].value);
   }
 
   const isPolyfillImport = {
     ImportDeclaration(path, state) {
       if (path.node.specifiers.length === 0 &&
-          path.node.source.value === polyfillSource) {
+          isPolyfillSource(path.node.source.value)) {
         this.numPolyfillImports++;
         if (this.numPolyfillImports > 1) {
           path.remove();
@@ -53,7 +55,7 @@ to the "transform-polyfill-require" plugin
 `);
       }
       path.get("body").forEach((bodyPath) => {
-        if (isRequire(bodyPath, polyfillSource)) {
+        if (isRequire(bodyPath)) {
           this.numPolyfillImports++;
           if (this.numPolyfillImports > 1) {
             path.remove();
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/core-js/actual.js b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/actual.js
new file mode 100644
index 0000000000..c3fee8a175
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/actual.js
@@ -0,0 +1 @@
+import "core-js";
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/core-js/expected.js b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/expected.js
new file mode 100644
index 0000000000..531f909e8e
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/expected.js
@@ -0,0 +1,2 @@
+import "core-js/modules/es7.string.pad-start";
+import "core-js/modules/es7.string.pad-end";
\ No newline at end of file
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/core-js/options.json b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/options.json
new file mode 100644
index 0000000000..de09fa3f05
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/core-js/options.json
@@ -0,0 +1,11 @@
+{
+  "presets": [
+    ["../../../../lib", {
+      "targets": {
+        "chrome": 55
+      },
+      "modules": false,
+      "useBuiltIns": true
+    }]
+  ]
+}
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/actual.js b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/actual.js
new file mode 100644
index 0000000000..31f2d79f9a
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/actual.js
@@ -0,0 +1,2 @@
+import "not-core-js";
+import "not-babel-polyfill";
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/expected.js b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/expected.js
new file mode 100644
index 0000000000..e6e20a7905
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/expected.js
@@ -0,0 +1,2 @@
+import "not-core-js";
+import "not-babel-polyfill";
\ No newline at end of file
diff --git a/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/options.json b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/options.json
new file mode 100644
index 0000000000..de09fa3f05
--- /dev/null
+++ b/experimental/babel-preset-env/test/fixtures/preset-options/no-transform/options.json
@@ -0,0 +1,11 @@
+{
+  "presets": [
+    ["../../../../lib", {
+      "targets": {
+        "chrome": 55
+      },
+      "modules": false,
+      "useBuiltIns": true
+    }]
+  ]
+}