No qualifying bean of type 'org.springframework.boot.web.server.test.client.TestRestTemplate' available

I'm trying to test my @RestController, but it doesn't work, giving me the error

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'studio.abos.springcalc.rest.ControllerTest': Unsatisfied dependency expressed through field 'restTemplate': No qualifying bean of type 'org.springframework.boot.web.server.test.client.TestRestTemplate' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

This is my controller:

@RestController
public class Controller {

    @PostMapping(path = "/calc-simple", produces = "application/json")
    public BigResults calcSimple(final @RequestBody BigParameters params) {
        // ...
    }
}

This is my test class:

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
final class ControllerTest {

    @LocalServerPort
    private int port;

    @Autowired
    private TestRestTemplate restTemplate;

    @Test
    void invalidBigInteger1() {
        final var testParams = new BigParameters("invalid", "6", List.of(), List.of(), 1);        
        restTemplate.postForObject("http://localhost:" + port + "/simple-calc", testParams, BigResults.class);
    }
}

I saw similar but outdated posts where the solution was to add the RANDOM_PORT annotation parameter, but I already did that. How can I fix it?

How about using the org.springframework.boot.test.web.client.TestRestTemplate instead of org.springframework.boot.web.server.test.client.TestRestTemplate?

In the SpringBoot's documentation, the TestRestTemplate is declared in the package org.springframework.boot.test.web.client.

https://docs.spring.io/spring-boot/api/java/org/springframework/boot/test/web/client/TestRestTemplate.html

If you need to add a test dependency, try just like below.

For a gradle project

testImplementation 'org.springframework.boot:spring-boot-starter-test'

For a maven project

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>