Fix destructuring in pipeline operator (#6515)

* Fix destructuring in pipeline operator

Fixes #6514.

* Run exec only on node 6

packages/babel-plugin-transform-pipeline-operator/src/index.js

@@ -18,9 +18,9 @@ export default function({ types: t }) {
 
         if (optimizeArrow) {
           const { params } = right;
-          if (params.length === 1) {
+          if (params.length === 1 && t.isIdentifier(params[0])) {
             param = params[0];
-          } else if (params.length > 1) {
+          } else if (params.length > 0) {
             optimizeArrow = false;
           }
         } else if (t.isIdentifier(right, { name: "eval" })) {

packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/actual.js

@@ -0,0 +1,7 @@
+// Array destructing
+const result = [0] |> ([x]) => x;
+assert.equal(result, 0);
+
+// Object destructuring
+const result2 = { y: 1, z: 2 } |> ({ y, z }) => y + z;
+assert.equal(result, 3);

packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/exec.js

@@ -0,0 +1,7 @@
+// Array destructing
+const result = [0] |> ([x]) => x;
+assert.equal(result, 0);
+
+// Object destructuring
+const result2 = { y: 1, z: 2 } |> ({ y, z }) => y + z;
+assert.equal(result2, 3);

packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/expected.js

@@ -0,0 +1,14 @@
+var _ref, _y$z;
+
+// Array destructing
+const result = (_ref = [0], (([x]) => x)(_ref));
+assert.equal(result, 0); // Object destructuring
+
+const result2 = (_y$z = {
+  y: 1,
+  z: 2
+}, (({
+  y,
+  z
+}) => y + z)(_y$z));
+assert.equal(result, 3);

packages/babel-plugin-transform-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/options.json

@@ -0,0 +1,3 @@
+{
+  "minNodeVersion": "6.0.0"
+}