Currently when provider verifier can't find the required plugin, it simply shutdown without any error message:

PACT_LOGLEVEL=debug phpunit example/provider/                                                                                                                                                          12:41:36
Xdebug: [Step Debug] Could not connect to debugging client. Tried: 127.0.0.1:9003 (through xdebug.client_host/xdebug.client_port).
PHPUnit 9.5.20 #StandWithUkraine

2023-04-03T05:41:46.951993Z DEBUG ThreadId(01) pact_ffi::verifier: pact_ffi::verifier::pactffi_verifier_add_directory_source FFI function invoked
2023-04-03T05:41:46.952030Z DEBUG ThreadId(01) pact_ffi::verifier: pact_ffi::verifier::pactffi_verifier_execute FFI function invoked
2023-04-03T05:41:46.952033Z DEBUG ThreadId(01) pact_ffi::verifier::handle: Pact source to verify = Dir(/home/myname/Projects/pact-php-csv/example/provider/tests/Contract/../../../broker/pacts)
2023-04-03T05:41:46.952639Z DEBUG ThreadId(01) pact_plugin_driver::catalogue_manager: Updated catalogue entries:
core/content-generator/binary
core/content-generator/json
core/content-matcher/json
core/content-matcher/multipart-form-data
core/content-matcher/text
core/content-matcher/xml
2023-04-03T05:41:46.952667Z DEBUG ThreadId(01) pact_plugin_driver::catalogue_manager: Updated catalogue entries:
core/matcher/v1-equality
core/matcher/v2-max-type
core/matcher/v2-min-type
core/matcher/v2-minmax-type
core/matcher/v2-regex
core/matcher/v2-type
core/matcher/v3-content-type
core/matcher/v3-date
core/matcher/v3-datetime
core/matcher/v3-decimal-type
core/matcher/v3-includes
core/matcher/v3-integer-type
core/matcher/v3-null
core/matcher/v3-number-type
core/matcher/v3-time
core/matcher/v4-array-contains
core/matcher/v4-equals-ignore-order
core/matcher/v4-max-equals-ignore-order
core/matcher/v4-min-equals-ignore-order
core/matcher/v4-minmax-equals-ignore-order
core/matcher/v4-not-empty
core/matcher/v4-semver
2023-04-03T05:41:46.952718Z DEBUG ThreadId(01) pact_verifier: Scanning "/home/myname/Projects/pact-php-csv/example/provider/tests/Contract/../../../broker/pacts"
2023-04-03T05:41:46.952871Z  INFO ThreadId(01) pact_verifier: Pact file requires plugins, will load those now
2023-04-03T05:41:46.952881Z DEBUG ThreadId(01) pact_plugin_driver::plugin_manager: Loading plugin PluginDependency { name: "csv", version: Some("0.0"), dependency_type: Plugin }
2023-04-03T05:41:46.952894Z DEBUG ThreadId(01) pact_plugin_driver::plugin_manager: Did not find plugin, will start it
2023-04-03T05:41:46.952896Z DEBUG ThreadId(01) pact_plugin_driver::plugin_manager: Loading plugin manifest for plugin PluginDependency { name: "csv", version: Some("0.0"), dependency_type: Plugin }
2023-04-03T05:41:46.952902Z DEBUG ThreadId(01) pact_plugin_driver::plugin_manager: Looking for plugin in "/home/myname/.pact/plugins"
2023-04-03T05:41:46.953001Z DEBUG ThreadId(01) pact_ffi::verifier: pact_ffi::verifier::pactffi_verifier_shutdown FFI function invoked
F                                                                   1 / 1 (100%)

Time: 00:00.080, Memory: 28.32 MB

There was 1 failure:

1) App\Provider\Tests\Contract\PactVerifyTest::testPactVerifyConsumer
Failed asserting that false is true.

/home/myname/Projects/pact-php-csv/example/provider/tests/Contract/PactVerifyTest.php:58

FAILURES!
Tests: 1, Assertions: 1, Failures: 1.

I think it should log an error message like:

Can't find plugin csv in /home/myname/.pact/plugins

Do you think so?

It does log an error, and also sets the FFI error message. See https://github.com/pact-foundation/pact-reference/blob/master/rust/pact_ffi/src/plugins/mod.rs#L102

yes, during verification

Yeah, https://github.com/pact-foundation/pact-reference/blob/master/rust/pact_ffi/src/verifier/handle.rs#L308

I will create a ticket for this improvement then

Good spot @Tien Vo