Fix sandbox restore not handling stubbed functions (#2667)

Author: thamion

lib/sinon/sandbox.js

@@ -408,7 +408,8 @@ function Sandbox(opts = {}) {
         const [object, property, types] = args;
 
         const isSpyingOnEntireObject =
-            typeof property === "undefined" && typeof object === "object";
+            typeof property === "undefined" &&
+            (typeof object === "object" || typeof object === "function");
 
         if (isSpyingOnEntireObject) {
             const ownMethods = collectOwnMethods(spy);

test/sandbox-test.js

@@ -1766,6 +1766,17 @@ describe("Sandbox", function () {
 
             assert.isUndefined(o.foo.callCount);
         });
+
+        it("restores all fields of a stubbed function", function () {
+            const sandbox = new Sandbox();
+            const o = function () {};
+            o.foo = function () {};
+
+            sandbox.stub(o);
+            sandbox.restore();
+
+            assert.isUndefined(o.foo.callCount);
+        });
     });
 
     describe("configurable sandbox", function () {