feat(cupertino): add task-level delegate impl

[mertalev]

This PR introduces a taskDelegate builder and exposes NSURLSessionTask's delegate property to enable use of task-level delegates. They are not used anywhere yet to minimize the scope of the PR, but will be used in cupertino_client.dart to replace the existing session-level delegate implementation.

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PR Health

Coverage ⚠️

File	Coverage
pkgs/cupertino_http/example/integration_test/url_session_delegate_test.dart	💔 Not covered
pkgs/cupertino_http/example/integration_test/url_session_task_test.dart	💔 Not covered
pkgs/cupertino_http/lib/src/cupertino_api.dart	💔 Not covered

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Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
cupertino_http	Breaking	2.4.0	3.0.0-wip	3.0.0-wip	✔️

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Unused Dependencies ⚠️

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cupertino_http

❗ Show Issues These packages are used outside lib/ but are not dev_dependencies: * convert * crypto * flutter_test * http_client_conformance_tests * http_image_provider * integration_test * provider * test * web_socket_conformance_tests These packages are only used outside lib/ and should be downgraded to dev_dependencies: * flutter These packages may be unused, or you may be using assets from these packages: * dart_flutter_team_lints Failed to update packages.

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""

Files
pkgs/cupertino_http/example/integration_test/url_session_delegate_test.dart
pkgs/cupertino_http/example/integration_test/url_session_task_test.dart
pkgs/cupertino_http/lib/src/cupertino_api.dart

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/cronet_http/example/integration_test/client_profile_test.dart
pkgs/cronet_http/example/integration_test/client_test.dart
pkgs/cronet_http/example/integration_test/cronet_engine_test.dart
pkgs/cronet_http/example/lib/book.dart
pkgs/cronet_http/example/lib/main.dart
pkgs/cronet_http/lib/cronet_http.dart
pkgs/cronet_http/lib/src/cronet_client.dart
pkgs/cupertino_http/example/integration_test/client_conformance_test.dart
pkgs/cupertino_http/example/integration_test/client_profile_test.dart
pkgs/cupertino_http/example/integration_test/client_test.dart
pkgs/cupertino_http/example/integration_test/http_url_response_test.dart
pkgs/cupertino_http/example/integration_test/main.dart
pkgs/cupertino_http/example/integration_test/mutable_url_request_test.dart
pkgs/cupertino_http/example/integration_test/ns_error_client_exception.dart
pkgs/cupertino_http/example/integration_test/url_cache_test.dart
pkgs/cupertino_http/example/integration_test/url_request_test.dart
pkgs/cupertino_http/example/integration_test/url_response_test.dart
pkgs/cupertino_http/example/integration_test/url_session_configuration_test.dart
pkgs/cupertino_http/example/integration_test/url_session_test.dart
pkgs/cupertino_http/example/integration_test/web_socket_conformance_test.dart
pkgs/cupertino_http/example/integration_test/web_socket_test.dart
pkgs/cupertino_http/example/lib/book.dart
pkgs/cupertino_http/example/lib/main.dart
pkgs/cupertino_http/lib/cupertino_http.dart
pkgs/cupertino_http/lib/src/cupertino_client.dart
pkgs/cupertino_http/lib/src/cupertino_web_socket.dart
pkgs/flutter_http_example/lib/book.dart
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API leaks ✔️

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[brianquinlan]

@mertalev Thanks!

Why didn't you just expose the delegate property on NSURLSessionTask?

[mertalev]

@mertalev Thanks!

Why didn't you just expose the delegate property on NSURLSessionTask?

The StreamingTask and WebSocketTask wrapped the earlier Swift-based implementation. I guess you're right that they aren't really needed since it's using Dart bindings now.

[mertalev]

I changed it to expose a taskDelegate property and added a URLSessionTask.delegate builder that shares its logic with the existing URLSession.delegate builder. Both CupertinoClient and CupertinoWebSocket can use this, which is nicer than what I originally had.

[brianquinlan]

Could you fix the analysis errors:

warning • The '!' will have no effect because the receiver can't be null • example/integration_test/url_session_delegate_test.dart:648:38 • unnecessary_non_null_assertion
warning • The '!' will have no effect because the receiver can't be null • example/integration_test/url_session_delegate_test.dart:694:38 • unnecessary_non_null_assertion
warning • The '!' will have no effect because the receiver can't be null • example/integration_test/url_session_delegate_test.dart:740:38 • unnecessary_non_null_assertion

Could you remove the @pragmas for now unless you have reason to believe that they actually improve performance?

Could you add tests for the delegates to https://github.com/dart-lang/http/blob/master/pkgs/cupertino_http/example/integration_test/url_session_task_test.dart ?

[mertalev]

Will do! Regarding the pragmas, they do make the disassembly look better with fewer closure allocations and all the if conditions get removed and dead-code eliminated. It's a micro-optimization in the grand scheme of things, though, so I can remove them if you prefer?

[brianquinlan]

Will do! Regarding the pragmas, they do make the disassembly look better with fewer closure allocations and all the if conditions get removed and dead-code eliminated. It's a micro-optimization in the grand scheme of things, though, so I can remove them if you prefer?

If you need to look at the disassembly and they make it easier, you can keep them. Thanks!

[mertalev]

I added the tests and removed the null assertions, so it should be good now.

[brianquinlan]

I'm doing a review now. Could you rebase/merge so that the CI will run?

BTW, I love your tests. They are amazing!

[brianquinlan]

Amazing job!