C#/Dart/PHP integration & idempotency tests fail on live Twitter description (binary unions + non-deterministic generation)

[gavinbarron]

What are you generating using Kiota, clients or plugins?

API Client/SDK

In what context or format are you using Kiota?

Source Build

Client library/SDK language

Csharp, Dart, PHP, Java, Ruby, Go, TypeScript

Describe the bug

The integration-tests and idempotency-tests workflows (which generate against the live https://api.twitter.com/2/openapi.json description) started failing after the upstream Twitter description changed (~2026-07-27). These failures are not caused by PR #7995 (which is TypeScript-only and fixes the TS binary-union TS2358 regression); the last green runs on main were 2026-07-23, and the description is fetched live at test time.

There are two distinct failure families:

1. Generated-code quality for primitive binary unions (integration) — the Twitter description now contains media properties typed as a primitive binary union (e.g. binary | base64, both mapping to a byte/binary type). This is the same root construct that #7995 fixes for TypeScript, but the Dart and PHP writers emit analytics-unfriendly code for it:

• Dart — dart analyze fails on unnecessary_null_comparison warnings (treated as errors), e.g.:

  warning - models/append_media_upload_request_media.dart:15:60 - The operand can't be 'null', so the condition is always 'true'. Remove the condition. - unnecessary_null_comparison
  warning - models/chat_media_upload_append_request_media.dart:18:65 - ...
  warning - models/media_upload_request_media.dart:15:60 - ...
  6 issues found.
  

• PHP — PHPStan fails with:

  Strict comparison using !== between null and null will always evaluate to false. (x3)
  ... in Microsoft\Kiota\Abstractions\Serialization\ParseNode::getBinaryContent
  [ERROR] Found 3 errors
  

2. Non-deterministic generation (idempotency) — generating twice from the same local description file produces differing output. The reordered content is byte-identical; only the ordering of the Analytics/models set differs between runs. This instability is language-agnostic and surfaces on a different language each CI run (a given run only needs one file to differ to fail). Observed reproductions:

Language	Differing file
C#	Models/Analytics.cs
Dart	models/news.dart
Java	apisdk/models/Analytics.java
Ruby	models/analytics.rb, models/models.rb
Go	models/analytics.go
TypeScript	models/index.ts (barrel/inlined model exports)

Because it whack-a-moles across languages, the Twitter idempotency leg is now suppressed for all languages (IdempotencySuppressions Language: all) rather than per-language.

Expected behavior

• Integration: generated Dart/PHP for primitive binary unions passes dart analyze / PHPStan with no errors.
• Idempotency: two generations from the same description produce byte-identical output for all languages.

Full breadth of work to complete

This issue is resolved only when all of the following are done:

A. Primitive binary union code quality (integration) — mirror the TypeScript #7995 fix in the other writers so no null-comparison noise is emitted for binary | base64 unions:

• Dart writer — eliminate unnecessary_null_comparison for primitive binary union models.
• PHP writer — eliminate PHPStan strict !== between null and null in binary union getters.
• Audit remaining languages (Go, Java, Python, Ruby, C#, CLI) for the same primitive-binary-union construct and fix any analogous code-quality issues.

B. Deterministic generation (idempotency) — make generation order stable so two runs from the same description are byte-identical. This is a core/shared fix (the ordering of the models/Analytics set), not a per-language patch:

• Identify and remove the source of non-determinism in model ordering/emission (shared builder/writer traversal — likely an unordered collection or hash-based ordering).
• Verify byte-identical output across two generations for the Twitter description for every language: C#, Dart, Java, Ruby, Go, TypeScript, PHP, Python, CLI.
• Add/confirm a deterministic-ordering regression test so this cannot silently regress.
• TypeScript specifically: the model barrel (models/index.ts) export/inline ordering must be deterministic.

C. Cleanup — once A and B are green, remove the temporary suppressions in it/config.json:

• Remove integration Suppressions for dart and php on the Twitter description.
• Remove the Twitter IdempotencySuppressions Language: all entry.
• Confirm CI is green for integration + idempotency across all languages without suppressions.

How to reproduce

1. Fetch the current https://api.twitter.com/2/openapi.json.
2. Run the integration harness for Dart and PHP: ./it/exec-cmd.ps1 flow (see integration-tests.yml).
3. Run the idempotency harness for any language: ./it/compare-generation.ps1 -descriptionUrl <twitter.json> -language <lang> (repeat runs; the failing language varies).

CI evidence:

• integration (dart): https://github.com/microsoft/kiota/actions/runs/30269157821/job/89987842099
• integration (php): https://github.com/microsoft/kiota/actions/runs/30269157821/job/89987838304
• idempotency (csharp): https://github.com/microsoft/kiota/actions/runs/30269161518/job/90072848648
• idempotency (dart): https://github.com/microsoft/kiota/actions/runs/30269161518/job/90072851371
• idempotency (typescript): https://github.com/microsoft/kiota/actions/runs/30859619868/job/91842000911
• idempotency (java): https://github.com/microsoft/kiota/actions/runs/30859619868/job/91841990000
• idempotency (ruby): https://github.com/microsoft/kiota/actions/runs/30859619868/job/91841995658
• idempotency (go): https://github.com/microsoft/kiota/actions/runs/30861589560/job/91845062924

Open API description file

https://api.twitter.com/2/openapi.json

Kiota Version

1.34.1 (source build / main)

Latest Kiota version known to work for scenario above?(Not required)

Green on main as of 2026-07-23 (#7983); regressed after the live Twitter description changed.

Known Workarounds

These matrix legs have been suppressed in it/config.json so unrelated PRs are not blocked:

• integration Suppressions for dart and php;
• IdempotencySuppressions Language: all for the Twitter description (collapsed from the earlier per-language entries because the non-determinism surfaces on a different language each run).

Suppressions must be removed once this issue is resolved (see Cleanup above).

Other information

Split of concerns:

• Dart/PHP (and any other affected languages) integration = writer changes needed to emit clean code for primitive binary unions (mirror of the TypeScript fix/typescript binary type #7995 fix).
• Idempotency = language-agnostic non-deterministic ordering of the Analytics/models set; needs a shared/core deterministic-ordering fix and must be validated for every language.

[gavinbarron]

Update: the non-deterministic idempotency failure now also reproduces for TypeScript, Java and Ruby on the live Twitter description — same root cause as the already-listed C#/Dart cases (byte-identical content, different ordering of the Analytics/models set):

• TypeScript — models/index.ts
• Java — apisdk/models/Analytics.java
• Ruby — models/analytics.rb, models/models.rb

TypeScript needs to be updated so the barrel/inlined model exports in models/index.ts are emitted in a stable, deterministic order. Reproduced locally by generating the Twitter description twice and diffing; unrelated to the binary-union fix in #7995 (TS integration passes). These legs have been added to IdempotencySuppressions in it/config.json referencing this issue and should be removed once the ordering is stabilized.

[gavinbarron]

Update: the idempotency non-determinism also reproduced for Go (models/analytics.go) on the latest CI run — the same language-agnostic ordering instability in the Analytics/models set. Since it surfaces on a different language each run (csharp, dart, java, ruby, go, typescript all observed), per-language suppression was whack-a-mole, so the Twitter IdempotencySuppressions have been collapsed into a single Language: all entry in it/config.json until the ordering is stabilized.

I've expanded the issue body with a "Full breadth of work to complete" checklist covering: (A) primitive binary-union code-quality fixes for Dart/PHP and an audit of the remaining writers, (B) a shared/core deterministic-generation fix validated byte-identical across every language (with TypeScript's models/index.ts barrel called out), and (C) removal of the temporary it/config.json suppressions once green.