Add tests to ensure options are not accidentally modified

package.json

@@ -38,7 +38,7 @@
     "lint": "jscs . && jshint . --exclude-path .gitignore",
     "standalone": "browserify index.js --standalone Pjax > pjax.js",
     "build-debug": "browserify index.js --debug --standalone Pjax > pjax.js",
-    "tests": "tape -r ./tests/setup.js ./tests/**/*.js",
+    "tests": "tape -r ./tests/setup.js ./tests/lib/*.js ./tests/lib/proto/*.js",
     "test": "npm run lint && npm run tests | tap-spec",
     "coverage-tests": "npm run tests | tap-nyc",
     "coverage": "nyc -x \"tests/**\" npm run coverage-tests",

tests/lib/proto/attach-form.js

@@ -76,3 +76,21 @@ tape("test attach form preventDefaulted events", function(t) {
 
   t.end()
 })
+
+tape("test options are not modified by attachForm", function(t) {
+  var form = document.createElement("form")
+  var options = {foo: "bar"}
+  var loadUrl = () => {}
+
+  attachForm.call({options, loadUrl}, form)
+
+  var internalUri = window.location.protocol + "//" + window.location.host + window.location.pathname + window.location.search
+  form.action = internalUri
+  form.method = "GET"
+  trigger(form, "submit")
+
+  t.equal(1, Object.keys(options).length, "options object that is passed in should not be modified")
+  t.equal("bar", options.foo, "options object that is passed in should not be modified")
+
+  t.end();
+})

tests/lib/proto/attach-link.js

@@ -75,3 +75,21 @@ tape("test attach link preventDefaulted events", function(t) {
 
   t.end()
 })
+
+tape("test options are not modified by attachLink", function(t) {
+  var a = document.createElement("a")
+  var options = {foo: "bar"}
+  var loadUrl = () => {};
+
+  attachLink.call({options, loadUrl}, a)
+
+  var internalUri = window.location.protocol + "//" + window.location.host + window.location.pathname + window.location.search
+  a.href = internalUri
+
+  trigger(a, "click")
+
+  t.equal(1, Object.keys(options).length, "options object that is passed in should not be modified")
+  t.equal("bar", options.foo, "options object that is passed in should not be modified")
+
+  t.end();
+})