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
@@ skipping 16 matching lines @@
   }
 };
 
 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);

[Manish Jethani, 2019/03/13 16:36:14]

Do we really need this timeout here?

[hub, 2019/03/14 10:28:05]

Without it, the test fail. With a 0 timeout, it fails just on Chrome.

[Manish Jethani, 2019/03/14 11:32:08]

Why is this though? Is it because the `<script>` element needs to be injected?

[hub, 2019/03/14 12:32:54]

that's what I think.

[Manish Jethani, 2019/03/16 10:50:24]

OK, I checked. It is indeed because the snippet returns before the code has
executed. Let's add a comment here then. Something like:

  // 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.

[hub, 2019/03/18 18:27:26]

Done.

 }
 
-exports.testAbortPropertyReadSnippet = async function(test)

[Manish Jethani, 2019/03/13 16:36:14]

Nit: We should maybe name this `testAbortOnPropertyReadSnippet`.

[hub, 2019/03/14 10:28:05]

Done.

+exports.testAbortOnPropertyReadSnippet = async function(test)
 {
-  window.abpTest = "foo";
-
-  async function testProperty(property, result = true)

[Manish Jethani, 2019/03/13 16:36:14]

This function doesn't have to be async from what I can tell.

[hub, 2019/03/14 10:28:05]

Done.

+  function testProperty(property, result = true, errorName = "ReferenceError")
   {
-    let properties = property.split(".");

[Manish Jethani, 2019/03/13 16:36:15]

Nit: We could call this `path` instead of `properties` as we have done in
`lib/content/snippets.js`. Your call.

[hub, 2019/03/14 10:28:04]

Done.

-    test.ok(properties.length >= 1);

[Manish Jethani, 2019/03/13 16:36:15]

This seems redundant. It is not possible for this check to fail.

[hub, 2019/03/14 10:28:04]

Done.

+    let path = property.split(".");
 
     let exceptionCaught = false;
     let value = 1;
+
     try

[Manish Jethani, 2019/03/13 16:36:14]

Nit: Would be cleaner to read if a line was left before and after the try/catch.

[hub, 2019/03/14 10:28:05]

Done.

     {
       let obj = window;
-      while (properties.length > 1)
-        obj = obj[properties.shift()];
-      value = obj[properties.shift()];
+      while (path.length > 1)
+        obj = obj[path.shift()];
+      value = obj[path.shift()];
     }
     catch (e)
     {
-      if (properties.length == 0)

[Manish Jethani, 2019/03/14 10:58:12]

Will properties.length every be non-zero here?

-        exceptionCaught = true;
+      test.equal(e.name, errorName);
+      exceptionCaught = true;
     }
-    test.equal(exceptionCaught, result, `The property "${property}" didn't trigger and exception.`);

[Manish Jethani, 2019/03/13 16:36:15]

The message here doesn't make complete sense. What if `result` is `false` and an
exception _is_ triggered?

[hub, 2019/03/14 10:28:04]

Done.

-    test.equal(value, result ? 1 : undefined, `The value for "${property}" shouldn't have been read.`);

[Manish Jethani, 2019/03/13 16:36:15]

Same as above. Both of these cases assume `result` is `true`.

[hub, 2019/03/14 10:28:05]

Done.

+
+    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 = "fortytwo";
   await runSnippet(test, "abort-on-property-read", "abpTest");
-  await testProperty("abpTest");
+  testProperty("abpTest");
 
-  window.abpTest2 = {prop1: "foo"};
+  window.abpTest2 = {prop1: "fortytwo"};
+  await runSnippet(test, "abort-on-property-read", "abpTest2.prop1");
+  testProperty("abpTest2.prop1");
 
-  await runSnippet(test, "abort-on-property-read", "abpTest2.prop1");
-  await testProperty("abpTest2.prop1");
-
-  // Test that we try to catch a property that don't exist yet.
+  // 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"};
-  await testProperty("abpTest3.prop1");
+  window.abpTest3 = {prop1: "fortytwo"};
+  testProperty("abpTest3.prop1");
 
   // Test that other properties don't trigger.
-  await testProperty("abpTest3.prop2", false);
+  testProperty("abpTest3.prop2", false);
 
-  // Test overwriting the object with another object
-  window.foo = {bar: {}};
-  await runSnippet(test, "abort-on-property-read", "foo.bar.lambda");
-  await testProperty("foo.bar.lambda");
-  window.foo.bar = {};
-  await testProperty("foo.bar.lambda");
+  // Test overwriting the object with another object.
+  window.abpTest4 = {prop3: {}};
+  await runSnippet(test, "abort-on-property-read", "abpTest4.prop3.foo");
+  testProperty("abpTest4.prop3.foo");
+  window.abpTest4.prop3 = {};
+  testProperty("abpTest4.prop3.foo");
 
-  // Test if we start with a non-object
-  window.foo2 = 5;
-  await runSnippet(test, "abort-on-property-read", "foo2.bar2.lambda");
-  await testProperty("foo2.bar2.lambda");
-  window.foo2 = {};
-  await testProperty("foo2.bar2.lambda");
+  // Test if we start with a non-object.
+  window.abpTest5 = 42;
+  await runSnippet(test, "abort-on-property-read", "abpTest5.prop4.bar");
+
+  testProperty("abpTest5.prop4.bar", true, "TypeError");
+
+  window.abpTest5 = {prop4: 42};
+  testProperty("abpTest5.prop4.bar", false);
+  window.abpTest5 = {prop4: {}};
+  testProperty("abpTest5.prop4.bar");
 
   test.done();
 };
-