Could not autowire field:RestTemplate in Spring boot application

It's exactly what the error says. You didn't create any RestTemplate bean, so it can't autowire any. If you need a RestTemplate you'll have to provide one. For example, add the following to TestMicroServiceApplication.java:

@Bean
public RestTemplate restTemplate() {
    return new RestTemplate();
}

Note, in earlier versions of the Spring cloud starter for Eureka, a RestTemplate bean was created for you, but this is no longer true.

Depending on what technologies you're using and what versions will influence how you define a RestTemplate in your @Configuration class.

Spring >= 4 without Spring Boot

Simply define an @Bean:

@Bean
public RestTemplate restTemplate() {
    return new RestTemplate();
}

Spring Boot <= 1.3

No need to define one, Spring Boot automatically defines one for you.

Spring Boot >= 1.4

Spring Boot no longer automatically defines a RestTemplate but instead defines a RestTemplateBuilder allowing you more control over the RestTemplate that gets created. You can inject the RestTemplateBuilder as an argument in your @Bean method to create a RestTemplate:

@Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
   // Do any additional configuration here
   return builder.build();
}

Using it in your class

@Autowired
private RestTemplate restTemplate;

Reference

If a TestRestTemplate is a valid option in your unit test, this documentation might be relevant

http://docs.spring.io/spring-boot/docs/1.4.1.RELEASE/reference/htmlsingle/#boot-features-rest-templates-test-utility

Short answer: if using

@SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)

then @Autowired will work. If using

@SpringBootTest(webEnvironment=WebEnvironment.MOCK)

then create a TestRestTemplate like this

private TestRestTemplate template = new TestRestTemplate();