Contents

Built-In Plugins

Otter comes with a few built-in plugins to optionally extend its own functionality. These plugins are documented here. Note: To use these plugins, specify the importable names exactly as seen here (i.e. otter.plugins.builtin.GoogleSheetsGradeOverride, not otter.plugins.builtin.grade_override.GoogleSheetsGradeOverride).

Google Sheets Grade Override

This plugin allows you to override test case scores during grading by specifying the new score in a Google Sheet that is pulled in. To use this plugin, you must set up a Google Cloud project and obtain credentials for the Google Sheets API. This plugin relies on gspread to interact with the Google Sheets API and its documentation contains instructions on how to obtain credentials. Once you have created credentials, download them as a JSON file.

This plugin requires two configurations: the path to the credentials JSON file and the URL of the Google Sheet. The former should be entered with the key credentials_json_path and the latter sheet_url; for example, in Otter Assign:

plugins:
    - otter.plugins.builtin.GoogleSheetsGradeOverride:
        credentials_json_path: /path/to/google/credentials.json
        sheet_url: https://docs.google.com/some/google/sheet

The first tab in the sheet is assumed to be the override information.

During Otter Generate, the plugin will read in this JSON file and store the relevant data in the otter_config.json for use during grading. The Google Sheet should have the following format:

Assignment ID Email Test Case Points PDF
123456 student@univ.edu q1a - 1 1 false

  • Assignment ID should be the ID of the assignment on Gradescope (to allow one sheet to be used for multiple assignments)

  • Email should be the student’s email address on Gradescope

  • Test Case should be the name of the test case as a string (e.g. if you have a test file q1a.py with 3 test cases, overriding the second case would be q1a - 2)

  • Points should be the point value to assign the student for that test case

  • PDF should be whether or not a PDF should be re-submitted (to prevent losing manual grades on Gradescope for regrade requests)

Note that the use of this plugin requires specifying gpsread in your requirements, as it is not included by default in Otter’s container image.

The actions taken by at hook for this plugin are detailed below.

otter.plugins.builtin.GoogleSheetsGradeOverride Reference

class otter.plugins.builtin.GoogleSheetsGradeOverride(submission_path, submission_metadata, plugin_config)

Otter plugin for overriding test case scores with values in a Google Sheet on Gradescope. Uses provided Google Service Account credentials to pull in the spreadsheet as a dataframe and edits test case scores by matching on the Gradescope assignment ID, student email, and test case name.

Implements the during_generate, before_grading, and after_grading events. Make sure to list this plugin as ``otter.plugins.builtin.GoogleSheetsGradeOverride``, otherwise the ``during_generate`` event of this plugin will not work.

The google sheet should have the following format:

Assignment ID

Email

Test Case

Points

PDF

123456

student@univ.edu

q1a - 1

1

false

Assignment ID should be the ID of the assignment on Gradescope, Email should be the email address corresponding to the student’s Gradescope account, Test Case should be the name of the test case, and Points should be the number of points that the student should be assigned. PDF should be false if the student’s PDF should not be regenerated during this run of the autograder.

after_grading(results)

Modifies the results of grading by pulling in the Google Sheet as a dataframe and updating the scores for the test cases found.

Parameters

results (otter.test_files.GradingResults) – the results of grading

before_grading(options)

Controls whether or not a PDF is generated by setting the token key of the grading options to None if any of the rows in the dataframe matching this (email, assignment ID) tuple indicate that a PDF should not be generated.

Parameters

options (dict) – the grading configurations

property df

The grade override information dataframe

during_generate(otter_config)

Takes a path to Google Service Account credentials stored in this plugin’s config as key credentials_json_path and extracts the data from that file into the plugin’s config as key service_account_credentials.

Parameters

otter_config (dict) – the parsed Otter configuration JSON file

Rate Limiting

This plugin allows instructors to limit the number of times students can submit to the autograder in any given window to prevent students from using the AG as an “oracle”. This plugin has a required configuration allowed_submissions, the number of submissions allowed during the window, and accepts optional configurations weeks, days, hours, minutes, seconds, milliseconds, and microseconds (all defaulting to 0) to configure the size of the window. For example, to specify 5 allowed submissions per-day in your otter_config.json:

{
    "plugins": [
        {
            "otter.plugins.builtin.RateLimiting": {
                "allowed_submissions": 5,
                "days": 1
            }
        }
    ]
}

When a student submits, the window is caculated as a datetime.timedelta object and if the student has at least allowed_submissions in that window, the submission’s results are hidden and the student is only shown a message; from the example above:

You have exceeded the rate limit for the autograder. Students are allowed 5 submissions every 1 days.

The results of submission execution are still visible to instructors.

If the student’s submission is allowed based on the rate limit, the plugin outputs a message in the plugin report; from the example above:

Students are allowed 5 submissions every 1 days. You have {number of previous submissions} submissions in that period.

The actions taken by at hook for this plugin are detailed below.

otter.plugins.builtin.RateLimiting Reference

class otter.plugins.builtin.RateLimiting(submission_path, submission_metadata, plugin_config)

Implements submission rate limiting by restricting the number of submissions a student is allowed during a specified window

This plugin is configured by defining the duration of the window using the optional keys weeks, days, hours, minutes, seconds, milliseconds, and microseconds (all of which default to 0). The number of submissions allowed during this window is configured with allowed_submissions. For example, to allow only 2 submissions every hour-and-a-half:

{
    "plugins": [
        {
            "otter.plugins.builtin.RateLimiting": {
                "hours": 1,
                "minutes": 30,
                "allowed_submissions": 2
            }
        }
    ]
}

When a student submits, the window is caculated as a datetime.timedelta object and if the student has at least allowed_submissions in that window, the submission’s results are hidden and the student is only shown a message; from the example above:

You have exceeded the rate limit for the autograder. Students are allowed 2 submissions every 1 hours 30 minutes.

The results of submission execution are still visible to instructors.

If the student’s submission is allowed based on the rate limit, the plugin outputs a message in the plugin report; from the example above:

Students are allowed 2 submissions every 1 hours 30 minutes. You have {number of previous submissions} submissions in that period.
after_grading(results)

Determines whether a student has exceeded the rate limit; if yes, all results are hidden from the student using otter.test_files.GradingResults.hide_everything and the output of the grader is set to the message.

Parameters

results (otter.test_files.GradingResults.hide_everything) – the results of grading

generate_report()

Returns the message regarding whether the rate limit was exceeded for inclusion in the plugin report.

Returns

the message

Return type

str

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