Add ability to log original and modified XML content in xml-prune scr…

…iptlet

src/scriptlets/xml-prune.js

@@ -35,6 +35,7 @@ import {
  * - `propsToMatch` — optional, XPath or selector of elements which will be removed from XML
  * - `optionalProp` — optional, selector of elements that must occur in XML document
  * - `urlToMatch` — optional, string or regular expression for matching the request's URL
+ * - `logContent` — optional, string to log original and modified XML content.
  *
  * > Usage with no arguments will log response payload and URL to browser console;
  * > it may be useful for debugging but it is not allowed for prod versions of filter lists.
@@ -59,6 +60,12 @@ import {
  *     example.org#%#//scriptlet('xml-prune', 'Period[id*="-ad-"]', '', '.mpd')
  *     ```
  *
+ * 1. Remove `Period` tag whose `id` contains `-ad-`, only if request's URL contains `.mpd` and log content
+ *
+ *     ```adblock
+ *     example.org#%#//scriptlet('xml-prune', 'Period[id*="-ad-"]', '', '.mpd', 'logContent')
+ *     ```
+ *
  * 1. Remove `Period` tag whose `id` contains `pre-roll` and remove `duration` attribute from the `Period` tag
  *    by using XPath expression
  *
@@ -86,7 +93,7 @@ import {
  */
 /* eslint-enable max-len */
 
-export function xmlPrune(source, propsToRemove, optionalProp = '', urlToMatch = '') {
+export function xmlPrune(source, propsToRemove, optionalProp = '', urlToMatch = '', logContent) {
     // do nothing if browser does not support Reflect, fetch or Proxy (e.g. Internet Explorer)
     // https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch
     // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
@@ -100,6 +107,8 @@ export function xmlPrune(source, propsToRemove, optionalProp = '', urlToMatch =
 
     let shouldPruneResponse = false;
 
+    const shouldLogContent = logContent === 'logContent';
+
     const urlMatchRegexp = toRegExp(urlToMatch);
 
     const XPATH_MARKER = 'xpath(';
@@ -193,13 +202,23 @@ export function xmlPrune(source, propsToRemove, optionalProp = '', urlToMatch =
             shouldPruneResponse = false;
             return text;
         }
+        if (shouldLogContent) {
+            // It's necessary to clone the XML document because xmlDoc is logged with removed elements
+            const cloneXmlDoc = xmlDoc.cloneNode(true);
+            logMessage(source, 'Original xml:');
+            logMessage(source, cloneXmlDoc, true, false);
+        }
         if (isXpath) {
             xPathPruning(elements);
         } else {
             elements.forEach((elem) => {
                 elem.remove();
             });
         }
+        if (shouldLogContent) {
+            logMessage(source, 'Modified xml:');
+            logMessage(source, xmlDoc, true, false);
+        }
         const serializer = new XMLSerializer();
         text = serializer.serializeToString(xmlDoc);
         return text;

tests/scriptlets/xml-prune.test.js

@@ -165,6 +165,42 @@ if (!isSupported) {
         done();
     });
 
+    test('fetch match URL - remove ads and log', async (assert) => {
+        assert.expect(4);
+
+        console.log = (...args) => {
+            if (args.length === 2 && args[1] instanceof XMLDocument) {
+                const xmlDocument = args[1];
+                const serializer = new XMLSerializer();
+                const text = serializer.serializeToString(xmlDocument);
+                if (text.includes('MPD') && text.includes('pre-roll-')) {
+                    assert.ok(text.includes('Period id="pre-roll-1-ad-1"'), 'should log original text in console');
+                }
+                if (text.includes('MPD') && !text.includes('pre-roll-')) {
+                    assert.notOk(text.includes('Period id="pre-roll-1-ad-1"'), 'should log modififed text in console');
+                }
+            }
+            nativeConsole(...args);
+        };
+
+        const MATCH_DATA = "Period[id*='-ad-']";
+        const OPTIONAL_MATCH = '';
+        const MATCH_URL = '.mpd';
+        const LOG_CONTENT = 'logContent';
+        const scriptletArgs = [MATCH_DATA, OPTIONAL_MATCH, MATCH_URL, LOG_CONTENT];
+
+        runScriptlet(name, scriptletArgs);
+
+        const done = assert.async();
+
+        const response = await fetch(MPD_OBJECTS_PATH);
+        const responseMPD = await response.text();
+
+        assert.notOk(responseMPD.includes('pre-roll-1-ad-1'));
+        assert.strictEqual(window.hit, 'FIRED', 'hit function fired');
+        done();
+    });
+
     test('fetch match URL, match optional argument - remove ads', async (assert) => {
         const MATCH_DATA = "Period[id*='-ad-']";
         const OPTIONAL_MATCH = 'AdaptationSet';