Spring-boot-test dependencies having to be manually imported inspite of them being present in Spring-boot-starter-parent - Why?

I am running a spring boot application with spring-boot-starter dependencies, am facing a compile errors in my test cases if I don't import the following test dependencies

• spring-boot-test
• spring-test
• assertj-core

My understanding is that these are present already in the spring-boot-starter-parent and I can see them too. However, because of the compile time errors I am forced to import them into pom.xml as below, but then I get warnings that

Duplicating managed version 1.5.6.RELEASE for spring-boot-test

Duplicating managed version 4.3.10.RELEASE for spring-test

and similiarly for assertj-core

You can see the places where the warnings occur in pom.xml here

And my pom.xml is as follows

 <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java.version>1.8</java.version>
    <json.version>20160810</json.version>   
</properties>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.6.RELEASE</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
    </dependency>
    <dependency>
        <groupId>org.eclipse.jdt.core.compiler</groupId>
        <artifactId>ecj</artifactId>
        <version>4.6.1</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.hateoas</groupId>
        <artifactId>spring-hateoas</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <!-- <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
    </dependency> -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-test</artifactId>
        <version>1.5.6.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>4.3.10.RELEASE</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.assertj</groupId>
        <artifactId>assertj-core</artifactId>
        <version>3.8.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.json</groupId>
        <artifactId>json</artifactId>
        <version>${json.version}</version>
    </dependency>

Parts of my code where the compile errors occurs if I dont include the test dependencies is below. The @SpringBootTest and the TestRestTemplate cannot be imported if the dependencies are not present.

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import com.fasterxml.jackson.core.JsonProcessingException;

@RunWith(SpringRunner.class) 
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT) 
public class MatchControllerTest {

    // Test RestTemplate to invoke the APIs.
    @Autowired
    private TestRestTemplate testRestTemplate;
    //....and other part of the code

Why is this happening ?

1. Why are the test dependencies having to be manually included in the pom.xml if they are already present in the spring-boot-starter-parent
2. Once included, it is showing a duplcating managed version warning (probably rightly so...).

I am probably doing something silly/wrong - please help !