Avoid tampering with globals and other modules' exports in tests (#2504)

* fix: do not modify the Function prototype when running tests

Made a single test fail as the Function prototype had been mutated by a later test in the test suite.

refs #2502

* fix: do not mutate matcher object message

This made 3 of the assertion tests fail when re-running as Sinon's spy formatter changed the exports of the samsam module

* Use latest version of samsam to get immutable messages

Ensure we cannot do the same mistake again

lib/sinon/spy-formatters.js

@@ -14,13 +14,14 @@ var slice = arrayProto.slice;
 
 function colorSinonMatchText(matcher, calledArg, calledArgMessage) {
     var calledArgumentMessage = calledArgMessage;
+    var matcherMessage = matcher.message;
     if (!matcher.test(calledArg)) {
-        matcher.message = color.red(matcher.message);
+        matcherMessage = color.red(matcher.message);
         if (calledArgumentMessage) {
             calledArgumentMessage = color.green(calledArgumentMessage);
         }
     }
-    return `${calledArgumentMessage} ${matcher.message}`;
+    return `${calledArgumentMessage} ${matcherMessage}`;
 }
 
 function colorDiffText(diff) {

package.json

@@ -75,7 +75,7 @@
   "dependencies": {
     "@sinonjs/commons": "^3.0.0",
     "@sinonjs/fake-timers": "^10.0.2",
-    "@sinonjs/samsam": "^7.0.1",
+    "@sinonjs/samsam": "^8.0.0",
     "diff": "^5.1.0",
     "nise": "^5.1.4",
     "supports-color": "^7.2.0"

test/spy-formatters-test.js

@@ -0,0 +1,21 @@
+"use strict";
+const { D } = require("./../lib/sinon/spy-formatters");
+const sinon = require("../lib/sinon");
+const { assert } = require("@sinonjs/referee");
+
+describe('formatter specifier "D"', function () {
+    it("should not mutate matchers passed as arguments", function () {
+        const matcher = sinon.match(function test() {
+            return false;
+        }, "something");
+        assert.equals(matcher.message, "something");
+
+        const stub = sinon.stub();
+
+        stub(1, 2, 3);
+        /* eslint-disable new-cap */
+        D(stub, [matcher]);
+
+        assert.equals(matcher.message, "something");
+    });
+});

test/stub-test.js

@@ -173,6 +173,7 @@ describe("stub", function () {
                 test: func,
             };
             func.aProp = 42;
+
             createStub(object, "test");
 
             assert.equals(object.test.aProp, 42);
@@ -1535,16 +1536,16 @@ describe("stub", function () {
         });
 
         it("stubs methods of function", function () {
-            var func = function () {
-                return;
-            };
+            class FunctionType extends Function {
+                func2() {
+                    return 42;
+                }
+            }
+
+            var func = new FunctionType();
             func.func1 = function () {
                 return;
             };
-            // eslint-disable-next-line no-proto
-            func.__proto__.func2 = function () {
-                return;
-            };
 
             createStub(func);