Issue 7236 - Handle sub properties in abort-on-property snippets

test/browser/snippets.js

+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-present eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+const library = require("../../lib/content/snippets.js");
+const {timeout} = require("./_utils");
+
+// We need this stub for the injector.
+window.browser = {
+  runtime: {
+    getURL: () => ""
+  }
+};
+
+async function runSnippet(test, snippetName, ...args)
+{
+  let snippet = library[snippetName];
+
+  test.ok(snippet);
+
+  snippet(...args);
+
+  // For snippets that run in the context of the document via a <script>
+  // element (i.e. snippets that use makeInjector()), we need to wait for
+  // execution to be complete.
+  await timeout(100);
+}
+
+exports.testAbortOnPropertyReadSnippet = async function(test)
+{
+  function testProperty(property, result = true, errorName = "ReferenceError")
+  {
+    let path = property.split(".");
+
+    let exceptionCaught = false;
+    let value = 1;
+
+    try
+    {
+      let obj = window;
+      while (path.length > 1)
+        obj = obj[path.shift()];
+      value = obj[path.shift()];
+    }
+    catch (e)
+    {
+      test.equal(e.name, errorName);
+      exceptionCaught = true;
+    }
+
+    test.equal(
+      exceptionCaught,
+      result,
+      `The property "${property}" ${result ? "should" : "shouldn't"} trigger an exception.`
+    );
+    test.equal(
+      value,
+      result ? 1 : undefined,
+      `The value for "${property}" ${result ? "shouldn't" : "should"} have been read.`
+    );
+  }
+
+  window.abpTest = "foo";
+  await runSnippet(test, "abort-on-property-read", "abpTest");
+  testProperty("abpTest");
+
+  window.abpTest2 = {prop1: "foo"};

[Manish Jethani, 2019/03/20 15:20:52]

Would be nice if we did't use "foo" for the value because it's a property name
in the tests. It's easier to read code when it follows some rules. I suggested
42 as the value, you could use anything but "foo", "bar", or "lambda".

[hub, 2019/03/20 16:19:05]

Done.

+  await runSnippet(test, "abort-on-property-read", "abpTest2.prop1");
+  testProperty("abpTest2.prop1");
+
+  // Test that we try to catch a property that doesn't exist yet.
+  await runSnippet(test, "abort-on-property-read", "abpTest3.prop1");
+  window.abpTest3 = {prop1: "foo"};
+  testProperty("abpTest3.prop1");
+
+  // Test that other properties don't trigger.
+  testProperty("abpTest3.prop2", false);
+
+  // Test overwriting the object with another object.
+  window.abpTest4 = {bar: {}};

[Manish Jethani, 2019/03/20 15:17:48]

If we agree about the convention here then it should be `abpTest4.prop1.foo`
rather than `abpTest4.bar.lambda`.

[hub, 2019/03/20 16:19:04]

Done.

[Manish Jethani, 2019/03/20 16:43:32]

LGTM

(What I really meant was that within a new level like `abpTest4`, the
sub-properties should again start from `prop1`, and within `prop1` they should
again start from `foo`. Anyway this is fine.)

[hub, 2019/03/20 16:52:16]

the intent was to really get these unique across the board.

+  await runSnippet(test, "abort-on-property-read", "abpTest4.bar.lambda");
+  testProperty("abpTest4.bar.lambda");
+  window.abpTest4.bar = {};
+  testProperty("abpTest4.bar.lambda");
+
+  // Test if we start with a non-object.
+  window.abpTest5 = 5;

[Manish Jethani, 2019/03/20 15:20:52]

Nit: Same as above, would be nice to use 42 consistently as the value when it's
not an object.

[hub, 2019/03/20 16:19:05]

Done.

+  await runSnippet(test, "abort-on-property-read", "abpTest5.bar2.lambda");
+
+  testProperty("abpTest5.bar2.lambda", true, "TypeError");

[Manish Jethani, 2019/03/20 15:17:48]

Similarly, `abpTest5.prop1.foo`

(Sorry, the next person who comes along would see the pattern and follow it.
Otherwise it's hard to keep track.)

[hub, 2019/03/20 16:19:04]

Done.

+
+  window.abpTest5 = {bar2: 42};
+  testProperty("abpTest5.bar2.lambda", false);
+  window.abpTest5 = {bar2: {}};
+  testProperty("abpTest5.bar2.lambda");
+
+  test.done();
+};