Make calledWith() assertions idempotent (#2407)

* Add failing test for idempotent calledWith

* Make calledWith() assertions idempotent

Previously, calledWith() modified the list of arguments (called and
expected) in place, so that repeated calls to calledWith() assertions
ended up being repeatedly escaped.

This fixes that behavior, copying the arguments out of the spy's
internal array before modifying them.

Author: cincodenada

lib/sinon/spy-formatters.js

@@ -72,29 +72,29 @@ module.exports = {
                 j < calledArgs.length || j < expectedArgs.length;
                 ++j
             ) {
-                if (calledArgs[j]) {
-                    calledArgs[j] = quoteStringValue(calledArgs[j]);
+                var calledArg = calledArgs[j];
+                var expectedArg = expectedArgs[j];
+                if (calledArg) {
+                    calledArg = quoteStringValue(calledArg);
                 }
 
-                if (expectedArgs[j]) {
-                    expectedArgs[j] = quoteStringValue(expectedArgs[j]);
+                if (expectedArg) {
+                    expectedArg = quoteStringValue(expectedArg);
                 }
 
                 message += "\n";
 
                 var calledArgMessage =
-                    j < calledArgs.length ? sinonFormat(calledArgs[j]) : "";
-                if (match.isMatcher(expectedArgs[j])) {
+                    j < calledArgs.length ? sinonFormat(calledArg) : "";
+                if (match.isMatcher(expectedArg)) {
                     message += colorSinonMatchText(
-                        expectedArgs[j],
-                        calledArgs[j],
+                        expectedArg,
+                        calledArg,
                         calledArgMessage
                     );
                 } else {
                     var expectedArgMessage =
-                        j < expectedArgs.length
-                            ? sinonFormat(expectedArgs[j])
-                            : "";
+                        j < expectedArgs.length ? sinonFormat(expectedArg) : "";
                     var diff = jsDiff.diffJson(
                         calledArgMessage,
                         expectedArgMessage

test/assert-test.js

@@ -2172,7 +2172,7 @@ describe("assert", function () {
                     "expected doSomething to be called once and with exact arguments \n" +
                     "Call 1:\n"
                 }${color.red("4")}\n${color.red("3")}\n${color.red(
-                    inspect(JSON.stringify('"bob"'))
+                    inspect('"bob"')
                 )}\nCall 2:`
             );
         });
@@ -2188,6 +2188,18 @@ describe("assert", function () {
             );
         });
 
+        it("assert.calledWith message is idempotent", function () {
+            this.obj.doSomething("hey");
+
+            this.message("calledWith", this.obj.doSomething, "");
+            this.message("calledWith", this.obj.doSomething, "");
+            this.message("calledWith", this.obj.doSomething, "");
+            assert.contains(
+                this.message("calledWith", this.obj.doSomething, ""),
+                '"hey"'
+            );
+        });
+
         it("assert.alwaysCalledWithExactly exception message", function () {
             this.obj.doSomething(1, 3, "hey");
             this.obj.doSomething(1, 3);