Add Guzzle 8 support while keeping Guzzle 7 compatible

[vencakrecl]

Fixes #621.

Allows guzzlehttp/guzzle: ^7.3 || ^8.0 and guzzlehttp/psr7: ^1.7 || ^2.0 || ^3.0, and fixes the API removals and behaviour changes Guzzle 8 introduces. Guzzle 7 stays supported; both majors are covered in CI.

What breaks under Guzzle 8

Break	Where
\GuzzleHttp\Utils::jsonEncode() removed	1007 call sites across 147 generated files
RequestException::getResponse() removed — only ResponseException subclasses carry a response	649 sync catch blocks + 649 async rejection handlers
No-response network failures are now NetworkException, not ConnectException	649 generated catch blocks
cURL errors 52, 55, 56 reclassified as NetworkException	RetryMiddlewareFactory silently stops retrying
RequestException::getHandlerContext() removed	lib/RetryMiddlewareFactory.php
Request method casing preserved verbatim	apiRequest(['method' => 'post']) sends literal post

The retry one is the quietest failure: TRANSIENT_CURL_ERROR_CODES = [52, 55, 56] are all NetworkException in Guzzle 8, so instanceof ConnectException never matches and connection-error retries become a no-op with no error. (In Guzzle 7 only 52 was ever a ConnectException, so 55 and 56 were never actually retried there either — this fixes that on both majors.)

Changes

Generated clients (codegen/, applied mechanically across 147 files)

• Request bodies use json_encode(..., JSON_THROW_ON_ERROR).
• Sync catch block and async rejection handler check for getResponse() before calling it, so a failure without a response produces an ApiException with null headers/body instead of a fatal Error. The async handler previously blew up on any responseless failure under Guzzle 7 as well.
• catch (ConnectException) becomes catch (Psr\Http\Client\NetworkExceptionInterface), which both majors implement.

Hand-written code (lib/)

• RetryMiddlewareFactory::getRetryFunctionByConnectionErrors() matches NetworkExceptionInterface and reads the cURL errno from the exception message.
• Retry deciders accept any PSR-7 RequestInterface/ResponseInterface instead of only the concrete GuzzleHttp\Psr7 classes.
• apiRequest() uppercases the method option.

Tests and CI

• New tests/Unit/GeneratedApiClientTest.php drives a generated client over a MockHandler: JSON body encoding, and error handling with and without a response, on both the sync and async paths. Verified as a real regression test by restoring an unpatched BasicApi.php — 2 errors + 1 failure, including Call to undefined method GuzzleHttp\Exception\ConnectException::getResponse().
• RetryMiddlewareFactoryTest no longer relies on the removed handler-context constructor argument.
• phpunit and phpspec now run a ['^7.3', '^8.0'] matrix.

Verification

23 tests and 139 specs pass against both guzzle 7.15.2 (with psr7 2.13.0) and guzzle 8.0.1 (with psr7 3.0.0 / promises 3.0.0). php-cs-fixer reports no changes.

Things checked and found not to be affected

• Header values: ObjectSerializer::toHeaderValue() always casts to string, so psr7 3.x's string-only header rule is satisfied.
• Psr7\Query::build(): only referenced in docblocks — ObjectSerializer::buildQuery() is a local implementation, so the new value validation does not apply.
• getConfig() in the generated API classes is the SDK's own method returning Configuration, unrelated to the removed ClientInterface::getConfig().
• Psr7\Utils::streamFor() / tryFopen() still exist in psr7 3.x and are called with strings and resources only.

Note for maintainers

codegen/ is generated outside this repository, and upstream openapi-generator's php/api.mustache still emits \GuzzleHttp\Utils::jsonEncode() and the unguarded getResponse(). The generator templates need the same three changes, or a regeneration will revert all 147 files.

🤖 Generated with Claude Code

[brandenrodgers]

Thanks for submitting this! I've updated our generator to apply the same edits that you've manually created, and have a PR with them here. You should be able to drop all edits to the codegen/ folder from this PR and we should be able to get this in (assuming all tests are looking good!).

[vencakrecl]

Confirmed that this branch includes the current upstream master (1e0bcd88), including #625, and the fork's master matches upstream.

After dropping the original codegen/ changes, I found 51 generated API clients that still contain GuzzleHttp\Utils::jsonEncode() and the old exception handling. For example, Webhooks\Api\SubscriptionsApi::createRequest() fails under Guzzle 8 with Call to undefined method GuzzleHttp\Utils::jsonEncode(), and a request failure without a response triggers the removed RequestException::getResponse() method. The Contacts client covered by the existing tests was already fixed, so those tests passed.

Commit 1dc1768 adds the compatibility edits back only for those 51 remaining clients. Could the generator changes also be applied to these clients so regeneration preserves the fixes?

The same commit fixes Guzzle 7 retry handling: cURL errors 55/56 are represented by RequestException, not ConnectException. We now recognize these errors through cURL handler context, retain context-based errno lookup where available, and fall back to the exception message for Guzzle 8. Regression tests cover the actual exception types, retry limits, configured error codes, and Webhooks JSON encoding and synchronous/asynchronous failures without a response.

Validation on PHP 8.5.10:

Dependencies	PHPUnit	phpspec
Guzzle 7.15.5 / PSR-7 2.13.1	26 tests, 72 assertions passed	139 examples passed
Guzzle 8.2.0 / PSR-7 3.1.0	26 tests, 78 assertions passed	139 examples passed

All 54 changed PHP files pass syntax checks, and git diff --check passes. PHPUnit reports 28 existing metadata deprecations on each version. These are local mocked-transport tests; the existing CI matrix will validate on PHP 8.2.

[vencakrecl]

@brandenrodgers Can you take a look at my comment ⬆️