Improve cookie parsing for the CookieChanger module

This includes parsing an empty cookie, which allows the CookieChanger users
to add values even if no cookie was sent in the first place. It also enables
adding a method for removing cookies in the future.

Unit tests for the parsing of basic cookies are included.

lib/CookieChanger.js

@@ -3,6 +3,7 @@ const {Ci} = require("chrome");
 
 // export CookieChanger
 exports.CookieChanger = CookieChanger;
+exports.Cookies = Cookies;
 
 // save all CookieChangers
 var listeners = [];
@@ -44,6 +45,11 @@ function Cookies(cookieString) {
 
     cookieString.split(/; */).forEach((cookie) => {
         var i = cookie.indexOf("=");
+
+        if(i == -1) {
+            return;
+        }
+
         this.cookies.set(cookie.substring(0, i), cookie.substring(i + 1));
     });
 }
@@ -95,18 +101,18 @@ function httpListener(event) {
     });
 
     if(applicableListeners.length > 0) {
+        var cookieString = "";
         try {
-            var cookieString = request.getRequestHeader("Cookie");
-        } catch(ex) {
-            return;
-        }
+            cookieString = request.getRequestHeader("Cookie");
+        } catch(ex) {}
 
         var cookies = new Cookies(cookieString);
 
         applicableListeners.forEach((listener) => {
             listener.callback(cookies);
         });
 
+        // setting an empty string (no cookies) deletes the header
         request.setRequestHeader("Cookie", cookies.unparse(), false);
     }
 }

test/test-cookies.js

@@ -0,0 +1,28 @@
+const {Cookies, modifyPrefCookie} = require("../lib/CookieChanger");
+
+exports.testCookieParsing = (assert) => {
+    var t = (cookieString) => {
+        return (new Cookies(cookieString)).unparse();
+    };
+
+    assert.equal(t(""), "");
+    assert.equal(t("a=b"), "a=b");
+    assert.equal(t("a=1; b=2"), "a=1; b=2");
+    assert.equal(t("b=2; a=1"), "b=2; a=1");
+
+    assert.equal(t("a=1;   b=2"), "a=1; b=2");
+    assert.equal(t("a=1; ; b=2"), "a=1; b=2");
+    assert.equal(t("a=1;; b=2"), "a=1; b=2");
+    assert.equal(t("a=1;;b=2"), "a=1; b=2");
+    assert.equal(t("a=1 ;b=2"), "a=1 ; b=2");
+
+    // Cookies uses a Map as its backend
+    assert.equal(t("a=1; a=2"), "a=2");
+
+    assert.equal(t("abc"), "");
+    assert.equal(t("abc="), "abc=");
+    assert.equal(t("=abc"), "=abc");
+    assert.equal(t("a=1; abc; b=2"), "a=1; b=2");
+};
+
+require('sdk/test').run(exports);