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README.rst Validator


This validator is a proposed replacement for the current add-on validator available at It is written entirely in python.


Python Libraries:

  • argparse
  • cssutils
  • rdflib
  • chardet
  • fastchardet

Python Libraries for Testing:

  • nose
  • coverage

You can install everything you need for running and testing with

pip install -r requirements.txt


A working copy of Spidermonkey (debug or non-debug is fine) is a required. The version installed must include support for the Parser API. Downloading and installing the latest copy of Tracemonkey from will include this API.

Documentation on getting the latest Spidermonkey source:

Once Spidermonkey is installed, the path to the JavaScript shell must be specified in the /validator/constants.php file in the SPIDERMONKEY_INSTALLATION variable. If this variable is set to None, no JavaScript tests will be run.


Run the validator as follows

python addon-validator <path to xpi> [-t <expected type>] [-o <output type>] [-v] [--boring] [--selfhosted]

The path to the XPI should point to an XPI file.

Expected Type:

The expected type should be one of the following values:

any (default)
Accepts any extension
Accepts only extensions
Accepts only themes
Accepts only dictionaries
Accepts only language packs
Accepts only OpenSearch XML files (unpackaged)
Accepts only multi-item XPI packages

Specifying an expected type will throw an error if the validator does not detect that particular type when scanning. All addon type detection mechanisms are used to make this determination.

Output Type:

The output type may be either of the following:

text (default)
Outputs a textual summary of the addo-on analysis. Supports verbose mode.
Outputs a JSON snippet representing a full summary of the add-on analysis.

Verbose Mode:

If the "-v" flag is set, the output will include informational messages in addition to errors and warnings. Informational messages contain information about the analysis that do not invalidate the add-on, but are contextually relevant.

Verbose mode will also output detailed descriptions of each summary item, as well as the file path and line number (if available).

This mode is only supported by certain output types. Output types that do not support verbose mode will output informational messages by default.

Boring Mode:

Boring mode, when activated, doesn't print colors to the terminal.

Determined Mode:

With determination comes perseverance. When in determined mode, the validator will not stop validating after errors present themselves in a particular tier. Traditionally, if an error tier fails, subsequent tiers are not executed. This flag ensures that those tiers are indeed run.

Note that enabling this option may cause issues with certain tests, as some higher-level tiers depend on information provided by lower tiers. This data may not be available as the add-on was never meant to make it to the higher tiers.


Text Output Mode:

In text output mode ("text"), output is structured in the format of one message per line. The messages are prefixed by their priority level (i.e.: "Warning: This is the message").

At the head of the text output is a block describing what the add-on type was determined to be.

JSON Output Mode:

In JSON output mode ("json"), output is formatted as a JSON snippet containing all messages. The format for the JSON output is that of the sample document below.

        "detected_type": "extension",
        "success": false,
    "rejected": false,
        "messagetree":{ /* ... */ },
        "messages": [
                        "uid": "123456789",
                        "id": ["module", "function", "error"],
                        "type": "error",
                        "message": "This is the error message text.",
                        "description": ["Description of the error message.",
                                        "Additional description text"],
                        "file": "",
                        "line": 0
                        "uid": "123456789",
                        "id": ["module", "function", "error"],
                        "type": "warning",
                        "message": "This is the warning message text.",
                        "description": "Description of the warning message.",
                        "file": "testfile.xml",
                        "line": 0
                        "uid": "123456789",
                        "id": ["module", "function", "error"],
                        "type": "notice",
                        "message": "This is the informational message text.",
                        "description": "Description of the info message."
                        "file": "chrome.manifest",
                        "line": 21
                        "uid": "123456789",
                        "id": ["module", "function", "error"],
                        "type": "error",
                        "message": "test.xpi > An error was found.",
                        "description": "This error happened within a subpackage."
                        "file": [
                        "line": 21

The message_tree element to the document above contains a series of JavaScript objects organized into a tree structure. The key of each element in the tree is the the name of each successive part of the validator that generated a particular message or set of messages (increasing in specificity as the depth of the tree increases). Each tree element also includes a series of additional nodes which provide extra information:

__errors - number - The number of errors generated in this node
__warnings - number - The number of warnings generated in this node
__notices - number - The number of messages generated in this node
__messages - list - A list of UIDs from messages in the `messages` node

JSON Notes:

When a subpackage exists, an angle bracket will delimit the subpackage name and the message text.

If no applicable file is available (i.e.: when a file is missing), the file value will be empty. If a file value is available within a subpackage, then the file attribute will be a list containing the name of the outermost subpackage's name, followed by each successive concentric subpackage's name, followed by the name of the file that the message was generated in. If no applicable file is available within a subpackage, the file attribute is identical, except the last element of the list in the file attribute is an empty string.

For instance, this tree would generate the following messages:

        |  |
        |  |-subsubpackage.xpi
        |     |
        |     |-chrome.manifest
        |     |-install.rdf
        "type": "notice",
        "message": "<em:type> not found in install.rdf",
        "description": " ... ",
        "file": "install.rdf",
        "line": 0
        "type": "error",
        "message": "Invalid chrome.manifest subject: override",
        "description": " ... ",
        "file": "chrome.manifest",
        "line": 7
        "type": "error",
        "message": "subpackage.xpi > install.rdf missing from theme",
        "description": " ... ",
        "file": ["subpackage.xpi", ""],
        "line": 0
        "type": "error",
        "message": "subpackage.xpi > subsubpackage.xpi > Invalid chrome.manifest subject: sytle",
        "description": " ... ",
        "file": ["subpackage.xpi", "subsubpackage.xpi", "chrome.manifest"],
        "line": 5


Unit tests can be run with

fab test

or, after setting the proper python path:


However, to turn run unit tests with code coverage, the appropriate command would be:

nosetests --with-coverage --cover-package=validator --cover-skip=validator.argparse,validator.outputhandlers.,validator.main --cover-inclusive --cover-tests

Note that in order to use the --cover-skip nose parameter, you must install the included patch for nose's plugin:

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