[Patch/32.2.2] feat: handle unknown enum values gracefully

[galesky-a]

Description

This PR introduces a "graceful fail" mechanism for enum deserialization. It ensures that when the Adyen API adds new enum values, the SDK remains functional by treating unknown values as null rather than throwing a JsonSerializationException.

Related PRs and runs:

• Generated code triggered by this action
• SDK Automation to target this branch and skip unsupported fields (ex: oneOf, allOf). Note that the only change from 31.1.3 is that LEM was bumped from V3 to V4.
• Tests run for Dotnet 8.0 and 6.0

Key Changes

• Added SafeStringEnumConverter, which extends StringEnumConverter. It catches serialization exceptions for unknown enum members and returns null for nullable enum types.
• Registered the new converter in JsonOperation.Deserialize() to apply it across all SDK operations.
• Modified modelGeneric.mustache to ensure all generated enum properties and constructor arguments are nullable, regardless of whether they are "required" in the API specification.. This is the most impactful change, this should always have been the case, it's the behavior the API was modeled to have, hence this change is considered a bugfix

Testing Infrastructure:

• Added test suite (SafeStringEnumConverterTest.cs) to verify that unknown enum values deserialize to null while known values continue to work as expected.

How to verify

• Run the new test suite: Adyen.Test/SafeStringEnumConverterTest.cs.
• Observe that providing an unknown string to a nullable enum field no longer crashes the JsonConvert process.

[gemini-code-assist]

Summary of Changes

Hello @galesky-a, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the robustness of JSON deserialization by introducing a mechanism to gracefully handle unknown enum values. Previously, encountering an unknown enum string during deserialization would lead to an exception. With this change, such values will now be deserialized to null for nullable enum properties, preventing application crashes due to API evolution or unexpected data. This is achieved through a new custom JSON converter and an update to the C# model generation template to make all enum properties nullable by default.

Highlights

• Graceful Enum Deserialization: A new SafeStringEnumConverter has been introduced to handle unknown enum values during JSON deserialization. Instead of throwing an exception, it will now deserialize unknown enum values to null for nullable enum properties, ensuring forward compatibility.
• Template Update for Nullable Enums: The modelGeneric.mustache template has been modified to ensure that all enum properties generated in C# models are nullable (?). This change is crucial for the SafeStringEnumConverter to function correctly by allowing null assignment for unknown enum values.
• New Test Cases: Two new test files (StringEnumConverterTest.cs and UnknownEnumDeserializationTest.cs) have been added to validate the new enum deserialization behavior, covering scenarios with known, unknown, and missing enum values, as well as serialization of null enum values.

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Changelog

• Adyen.Test/StringEnumConverterTest.cs
  • Added a new test file to demonstrate the default behavior of StringEnumConverter (throwing an exception for unknown values) and to ensure null and known values are handled correctly.
• Adyen.Test/UnknownEnumDeserializationTest.cs
  • Added a new test file to specifically verify the SafeStringEnumConverter's behavior, ensuring unknown enum values deserialize to null and known values deserialize correctly across various scenarios, including webhook data.
• Adyen/Util/SafeStringEnumConverter.cs
  • Added a new custom JsonConverter that extends StringEnumConverter to catch JsonSerializationException for unknown enum values and return null if the target enum type is nullable.
• templates/csharp/modelGeneric.mustache
  • Modified the template to append ? to all generated enum properties, making them nullable by default. This change ensures compatibility with the SafeStringEnumConverter.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/build-net-6.yml

Activity

• The pull request title indicates a patch for version 32.2.2, suggesting this is a bug fix or feature addition for an existing release.
• The description is minimal, indicating that the changes are self-explanatory or follow a known issue.

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[gemini-code-assist]

Code Review

This pull request introduces a SafeStringEnumConverter to gracefully handle unknown enum values during JSON deserialization by converting them to null instead of throwing an exception. This improves the forward compatibility of the API client. The changes include the converter itself, comprehensive unit tests demonstrating the new behavior, and updates to the C# model generation templates to make enum properties nullable. The implementation is solid and the tests are thorough. I have one suggestion to improve the formatting of JSON strings in the tests for better readability and robustness.

[gemini-code-assist]

Using multi-line raw string literals for JSON can introduce unintended whitespace (like newlines and indentation) which might cause issues with some JSON parsers. For better readability and to ensure the JSON is correctly formatted, it's recommended to define test JSON on a single line. This makes the test less prone to formatting errors. This feedback applies to other small JSON string definitions in this test file. For larger JSON payloads like in TestTransferWebhookWithUnknownReasonEnum, consider moving them to an embedded resource file to keep the test code clean.

            var json = @"{\"channel\":\"UnknownChannelValue\",\"amount\":{\"value\":1000,\"currency\":\"EUR\"},\"reference\":\"test-ref\",\"merchantAccount\":\"test-merchant\"}";