Add unit tests for partial input optional field behaviour in update mutations

[SupImDos]

Description

As noted in the module's docstring, this PR adds some unit tests for Strawberry-Django's handling of partial input optional fields in update mutations, specifically when their values are omitted or explicitly set to null, for different variations of model fields:

• Required fields
• Optional and nullable fields
• Optional and non-nullable fields
• Required foreign key fields
• Optional foreign key fields
• Many-to-many fields

These tests stem from the fact that the GraphQL type-system doesn't distinguish between optional and nullable. That is, type T! is both required and non-nullable (i.e., must be supplied and cannot be null), but type T is both optional and nullable (i.e., can be omitted and can be null).

These tests uncovered what I believe is a small bug in update_m2m, where a value of None wasn't being explicitly checked.

For reference, we were going to add similar unit tests to our project, but thought they might be useful upstream.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Documentation

Issues Fixed or Closed by This PR

• N/A

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

Summary by Sourcery

Add unit tests for handling partial input optional fields in update mutations, covering various model field types and ensuring correct behavior when values are omitted or set to null. Fix a bug in the update_m2m function to handle None values correctly.

Bug Fixes:

• Fix a bug in the update_m2m function where a value of None was not being explicitly checked, ensuring correct handling of None values.

Tests:

• Add comprehensive unit tests to verify the behavior of partial input optional fields in update mutations for various model field types, including required fields, optional and nullable fields, optional and non-nullable fields, required foreign key fields, optional foreign key fields, and many-to-many fields.
• Include tests for both standard and Relay GraphQL mutations to ensure consistent handling of omitted and null values across different field types.

[sourcery-ai]

🧙 Sourcery has finished reviewing your pull request!

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time. You can also use
  this command to specify where the summary should be inserted.

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[sourcery-ai]

Hey @SupImDos - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[SupImDos]

@sourcery-ai review

[sourcery-ai]

Hey @SupImDos - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[sourcery-ai]

We have skipped reviewing this pull request. It looks like we've already reviewed the commit cf21c16 in this pull request.

[bellini666]

Thank you very much for this! ❤️