[[features-custom-mode]]
= Custom Mode

include::partial$_attributes.adoc[]

IMPORTANT: This mode is experimental and can change in the future.

The Spring Cloud Contract lets you provide your own, custom, implementation of the
`org.springframework.cloud.contract.verifier.http.HttpVerifier`. That way, you can use any client you want to send and receive a request. The default implementation in Spring Cloud Contract is `OkHttpHttpVerifier` and it uses OkHttp3 http client.

To get started, set `testMode` to `CUSTOM`:

====
[source,groovy,indent=0]
----
testMode = 'CUSTOM'
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The following example shows a generated test:

====
[source,java,indent=0]
----
package com.example.beer;

import com.example.BeerRestBase;
import javax.inject.Inject;
import org.springframework.cloud.contract.verifier.http.HttpVerifier;
import org.springframework.cloud.contract.verifier.http.Request;
import org.springframework.cloud.contract.verifier.http.Response;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;

import static org.springframework.cloud.contract.verifier.assertion.SpringCloudContractAssertions.assertThat;
import static org.springframework.cloud.contract.verifier.util.ContractVerifierUtil.*;
import static org.springframework.cloud.contract.verifier.http.Request.given;

@SuppressWarnings("rawtypes")
public class RestTest extends BeerRestBase {
	@Inject HttpVerifier httpVerifier;

	@Test
	public void validate_shouldGrantABeerIfOldEnough() throws Exception {
		// given:
			Request request = given()
					.post("/beer.BeerService/check")
					.scheme("HTTP")
					.protocol("h2_prior_knowledge")
					.header("Content-Type", "application/grpc")
					.header("te", "trailers")
					.body(fileToBytes(this, "shouldGrantABeerIfOldEnough_request_PersonToCheck_old_enough.bin"))
					.build();


		// when:
			Response response = httpVerifier.exchange(request);


		// then:
			assertThat(response.statusCode()).isEqualTo(200);
			assertThat(response.header("Content-Type")).matches("application/grpc.*");
			assertThat(response.header("grpc-encoding")).isEqualTo("identity");
			assertThat(response.header("grpc-accept-encoding")).isEqualTo("gzip");

		// and:
			assertThat(response.getBody().asByteArray()).isEqualTo(fileToBytes(this, "shouldGrantABeerIfOldEnough_response_Response_old_enough.bin"));
	}

}
----
====

The following example shows a corresponding base class:

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[source,java,indent=0]
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@SpringBootTest(classes = BeerRestBase.Config.class,
		webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public abstract class BeerRestBase {

	@Configuration
	@EnableAutoConfiguration
	static class Config {

		@Bean
		ProducerController producerController(PersonCheckingService personCheckingService) {
			return new ProducerController(personCheckingService);
		}

		@Bean
		PersonCheckingService testPersonCheckingService() {
			return argument -> argument.getAge() >= 20;
		}

		@Bean
		HttpVerifier httpOkVerifier(@LocalServerPort int port) {
			return new OkHttpHttpVerifier("localhost:" + port);
		}

	}
}
----
====