Throw better errors for non-iterables when Symbol doesn't exist (#11264)

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/exec.js

@@ -0,0 +1,13 @@
+var a = (() => [1, 2, 3])();
+
+// Simulate old environment
+let _Symbol = Symbol;
+Symbol = void 0;
+try {
+  var [first, ...rest] = a;
+
+  expect(first).toBe(1);
+  expect(rest).toEqual([2, 3]);
+} finally {
+  Symbol = _Symbol;
+}

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/input.js

@@ -0,0 +1,6 @@
+var a = (() => [1, 2, 3])();
+
+// !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toArray, please modify this test
+// and exec.js
+var [first, ...rest] = a;

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/array-symbol-unsupported/output.js

@@ -0,0 +1,8 @@
+var a = (() => [1, 2, 3])(); // !!! In order to run this test, this shouldn't be optimized using type inference
+// If it's optimized and doesn't call toArray, please modify this test
+// and exec.js
+
+
+var _a = babelHelpers.toArray(a),
+    first = _a[0],
+    rest = _a.slice(1);

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/non-iterable/exec.js

@@ -1,9 +1,22 @@
-expect(
-  () => {
-    var [foo, bar] = undefined;
-  }).toThrow("Invalid attempt to destructure non-iterable instance");
+var foo, bar;
 
 expect(
-  () => {
-    var foo = [ ...undefined ];
-  }).toThrow("Invalid attempt to spread non-iterable instance");
+  () => [foo, bar] = undefined
+).toThrow(/destructure non-iterable/);
+
+expect(
+  () => [foo, bar] = {}
+).toThrow(/destructure non-iterable/);
+
+// Simulate old browser
+let _Symbol = Symbol;
+Symbol = void 0;
+try {
+
+  expect(
+    () => [foo, bar] = {}
+  ).toThrow(/destructure non-iterable/);
+
+} finally {
+  Symbol = _Symbol;
+}

packages/babel-plugin-transform-destructuring/test/fixtures/destructuring/non-iterable/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    "transform-destructuring"
+  ]
+}