We use on the project Cassandra + Spring Boot.
Here are the steps which worked for us:
a) Configure you test like this
import org.cassandraunit.spring.CassandraDataSet;
import org.cassandraunit.spring.CassandraUnitDependencyInjectionTestExecutionListener;
import org.cassandraunit.spring.CassandraUnitTestExecutionListener;
import org.cassandraunit.spring.EmbeddedCassandra;
@RunWith(SpringRunner.class)
@SpringBootTest(classes = TestConfiguration.class)
@TestExecutionListeners(listeners = {
    CassandraUnitDependencyInjectionTestExecutionListener.class,
    CassandraUnitTestExecutionListener.class,
    ServletTestExecutionListener.class,
    DependencyInjectionTestExecutionListener.class,
    DirtiesContextTestExecutionListener.class
})
@EmbeddedCassandra(timeout = 60000)
@CassandraDataSet(value = {"bootstrap_test.cql"}, keyspace = "local_test")
public abstract class BaseTest {
b) in your src/test/resources/application.properties, add this (please note, embedded cassandra starts on port 9142, but not on default 9042)
spring.data.cassandra.port=9142
spring.data.cassandra.keyspace-name=local_test
c) Create empty file bootstrap_test.cql in src/test/resources
d) Add to your pom.xml
    <dependency>
        <groupId>org.cassandraunit</groupId>
        <artifactId>cassandra-unit-spring</artifactId>
        <version>${cassandra-unit.version}</version>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.cassandraunit</groupId>
                <artifactId>cassandra-unit</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.cassandraunit</groupId>
        <artifactId>cassandra-unit-spring</artifactId>
        <version>${cassandra-unit.version}</version>
    </dependency>
This should be enough to run your tests with Embedded Cassandra. 
Hope it helps.