import au.com.dius.pact.consumer.MockServer;
import au.com.dius.pact.consumer.dsl.PactBuilder;
import au.com.dius.pact.consumer.junit.MockServerConfig;
import au.com.dius.pact.consumer.junit5.PactConsumerTestExt;
import au.com.dius.pact.consumer.junit5.PactTestFor;
import au.com.dius.pact.consumer.junit5.ProviderType;
import au.com.dius.pact.consumer.model.MockServerImplementation;
import au.com.dius.pact.core.model.PactSpecVersion;
import au.com.dius.pact.core.model.V4Interaction;
import au.com.dius.pact.core.model.V4Pact;
import au.com.dius.pact.core.model.annotations.Pact;
import com.atoss.template.servicetemplate.adapter.handler.grpc.employee.v1.EmployeeServiceGrpc;
import com.atoss.template.servicetemplate.adapter.handler.grpc.employee.v1.Message;
import com.atoss.template.servicetemplate.adapter.handler.grpc.employee.v1.MessageRequest;
import com.google.protobuf.InvalidProtocolBufferException;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;

import java.util.List;
import java.util.Map;

import static org.hamcrest.MatcherAssert.assertThat;
import static <http://org.hamcrest.Matchers.is|org.hamcrest.Matchers.is>;

@ExtendWith(PactConsumerTestExt.class)
@PactTestFor(providerName = "adapter-handler-grpc", providerType = ProviderType.SYNCH_MESSAGE, pactVersion = PactSpecVersion.V4)
public class PactConsumerTest {

    @Pact(consumer = "adapter-client-grpc")
    V4Pact testMsg(PactBuilder builder) {
        return builder
                // Tell Pact we need the Protobuf plugin
                .usingPlugin("protobuf", "0.1.8")
                // We will use a V4 synchronous message interaction for the test
                .expectsToReceive("message", "core/interaction/synchronous-message")
                // We need to pass all the details for the interaction over to the plugin
                .with(Map.of(
                        // Configure the proto file, the content type and the service we expect to invoke
                        "pact:proto", builder.filePath("../adapter-handler-grpc-proto/src/main/resources/proto/EmployeeService.proto"),
                        "pact:content-type", "application/grpc",
                        "pact:proto-service", "EmployeeService/getEmployee",

                        // Details on the request message (ShapeMessage) we will send
                        "request", Map.of("id", 1),

                        // Details on the response message we expect to get back (AreaResponse)
                        "response", List.of(
                                Map.of(
                                        "msg", "Hello Grpc"
                                )
                        )
                ))
                .toPact();
    }

    @Test
    @PactTestFor(pactMethod = "testMsg")
    @MockServerConfig(implementation = MockServerImplementation.Plugin, registryEntry = "protobuf/transport/grpc")
    void readMessage(MockServer mockServer, V4Interaction.SynchronousMessages interaction) throws InvalidProtocolBufferException {
        ManagedChannel channel = ManagedChannelBuilder.forTarget("[::1]:" + mockServer.getPort())
                .usePlaintext()
                .build();
        EmployeeServiceGrpc.EmployeeServiceBlockingStub clientStub = EmployeeServiceGrpc
                .newBlockingStub(channel);

        Message response = clientStub.getMessage(MessageRequest.newBuilder().setId(1).build());
        System.out.println("after response");
        assertThat(response.getMsg(), is("{\"msg\":\"Hello Grpc\"}"));
    }

}

<dependency>
    <groupId>com.google.protobuf</groupId>
    <artifactId>protobuf-java-util</artifactId>
    <version>3.21.4</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.pact.plugin.driver</groupId>
    <artifactId>core</artifactId>
    <version>0.0.7</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>au.com.dius.pact.consumer</groupId>
     <artifactId>junit5</artifactId>
      <version>4.4.0-beta.3</version>
 </dependency>

[main] INFO <http://au.com|au.com>.dius.pact.consumer.junit5.PactConsumerTestExt - Writing pacts out to default directory