Fix issue with Object containing a __proto__ property.

This was caused because we used Object.assign which calls setters and stripped the __proto__ property.
Fixes #986.

Author: nchevobbe

packages/devtools-reps/src/reps/grip.js

@@ -153,7 +153,7 @@ function propIterator(props, object, max) {
   let propertiesLength = getPropertiesLength(object);
 
   if (object.preview && object.preview.safeGetterValues) {
-    properties = Object.assign({}, properties, object.preview.safeGetterValues);
+    properties = {...properties, ...object.preview.safeGetterValues};
   }
 
   let indexes = getPropIndexes(properties, max, isInterestingProp);

packages/devtools-reps/src/reps/stubs/grip.js

@@ -1004,4 +1004,43 @@ stubs.set("DeadObject", {
   "sealed": false
 });
 
+// Packet for :
+// var obj = Object.create(null); obj.__proto__ = []; obj;
+stubs.set("ObjectWith__proto__Property", {
+  "type": "object",
+  "actor": "server1.conn1.child1/obj31",
+  "class": "Object",
+  "extensible": true,
+  "frozen": false,
+  "sealed": false,
+  "ownPropertyLength": 1,
+  "preview": {
+    "kind": "Object",
+    "ownProperties": {
+      ["__proto__"]: {
+        "configurable": true,
+        "enumerable": true,
+        "writable": true,
+        "value": {
+          "type": "object",
+          "actor": "server1.conn1.child1/obj32",
+          "class": "Array",
+          "extensible": true,
+          "frozen": false,
+          "sealed": false,
+          "ownPropertyLength": 1,
+          "preview": {
+            "kind": "ArrayLike",
+            "length": 0
+          }
+        }
+      }
+    },
+    "ownSymbols": [],
+    "ownPropertiesLength": 1,
+    "ownSymbolsLength": 0,
+    "safeGetterValues": {}
+  }
+});
+
 module.exports = stubs;

packages/devtools-reps/src/reps/tests/grip.js

@@ -7,6 +7,7 @@
 const { shallow } = require("enzyme");
 const {
   getRep,
+  Rep,
 } = require("../rep");
 const Grip = require("../grip");
 const { MODE } = require("../constants");
@@ -21,9 +22,10 @@ const {
 const {maxLengthMap} = Grip;
 
 function shallowRenderRep(object, props = {}) {
-  return shallow(Grip.rep(Object.assign({
+  return shallow(Grip.rep({
     object,
-  }, props)));
+    ...props
+  }));
 }
 
 describe("Grip - empty object", () => {
@@ -603,3 +605,21 @@ describe("Grip - DeadObject object", () => {
     expect(renderRep({ mode: MODE.LONG }).text()).toBe(defaultOutput);
   });
 });
+
+describe("Grip - Object with __proto__ property", () => {
+  const object = stubs.get("ObjectWith__proto__Property");
+
+  it("correctly selects Grip Rep", () => {
+    expect(getRep(object)).toBe(Grip.rep);
+  });
+
+  it("renders as expected", () => {
+    const renderRep = (props) => shallow(Rep({object, ...props}));
+    const defaultOutput = "Object { __proto__: [] }";
+
+    expect(renderRep({ mode: undefined }).text()).toBe(defaultOutput);
+    expect(renderRep({ mode: MODE.TINY }).text()).toBe("{…}");
+    expect(renderRep({ mode: MODE.SHORT }).text()).toBe(defaultOutput);
+    expect(renderRep({ mode: MODE.LONG }).text()).toBe(defaultOutput);
+  });
+});