test(data): Gen2 data customize data model doc example testing

[lawmicha]

Issue #

Description

This PR uses the schemas from the Gen2 docs and runs integration tests against them to verify code snippet compiles and functions as expected at runtime. The code snippets are then moved over to the docs PR #3699

Found an issue with one-to-one, tracking in #3735

General Checklist

• Added new tests to cover change, if needed
• Build succeeds with all target using Swift Package Manager
• All unit tests pass
• All integration tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• New or updated tests include Given When Then inline code documentation and are named accordingly testThing_condition_expectation()
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[lawmicha]

on Swift codegen, this doesn't compile

// Gen2_4 - Model a "one-to-one" relationship
    // https://docs.amplify.aws/swift/build-a-backend/data/data-modeling/relationships/#model-a-one-to-one-relationship
    Cart4: a.model({
        items: a.string().required().array(),
        // 1. Create reference field
        customerId: a.id(),
        // 2. Create relationship field with the reference field
        customer: a.belongsTo('Customer4', 'customerId'),
    }),
    Customer4: a.model({
        name: a.string(),
        // 3. Create relationship field with the reference field
        //    from the Cart model
        activeCart: a.hasOne('Cart4', 'customerId')
    }),

Customer4 schema has

.hasOne(customer4.activeCart, is: .optional, ofType: Cart4.self, associatedFields: [Cart4.keys.customer]),

hasOne associatedFields doesn't exist. I think we might be able to easily add it. do we need to add targetName as well? Those methods are defined over in https://github.com/aws-amplify/amplify-swift/blob/main/Amplify/Categories/DataStore/Model/Internal/Schema/ModelSchema%2BDefinition.swift#L232-L306

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.06%. Comparing base (d888124) to head (eb4b388).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3699      +/-   ##
==========================================
+ Coverage   68.37%   70.06%   +1.68%     
==========================================
  Files        1096      637     -459     
  Lines       38089    24773   -13316     
==========================================
- Hits        26044    17356    -8688     
+ Misses      12045     7417    -4628     

Flag	Coverage Δ
API_plugin_unit_test	68.96% <ø> (ø)
AWSPluginsCore	65.67% <ø> (ø)
Amplify	?
Analytics_plugin_unit_test	84.52% <ø> (ø)
Auth_plugin_unit_test	79.27% <ø> (-0.20%)	⬇️
CoreMLPredictions_plugin_unit_test	61.15% <ø> (ø)
DataStore_plugin_unit_test	?
Geo_plugin_unit_test	73.50% <ø> (ø)
Logging_plugin_unit_test	62.87% <ø> (ø)
Predictions_plugin_unit_test	37.31% <ø> (ø)
PushNotifications_plugin_unit_test	86.21% <ø> (ø)
Storage_plugin_unit_test	76.75% <ø> (ø)
unit_tests	70.06% <ø> (+1.68%)	⬆️

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[thisisabhash]

LGTM, minor comments

[thisisabhash]

just a note: since we are comparing floating point, hopefully XCTAssertEqual uses
https://developer.apple.com/documentation/swift/double/isequal(to:)
in case this test becomes flaky

[thisisabhash]

nit: change the local url to docs url

[lawmicha]

thanks, i'll merge this PR in first and update this line in the other one #3705 to avoid rebasing since that one and is merging into this branch and also has some minor changes to do