Hi ✋, 

The hardest part of writing the unit test is creating mocks for external libraries, the purpose of this article is to help someone who has problems mocking a library like this.

Today I'm going to code how to mock your lambda invoke function in 'aws-sdk' using a jest 💪.

I'm going to write test cases for the below code. This is a simple cache service provider. it contains a getter and a setter.

CacheServiceProvider.ts

In here, I want to mock lambda.invoke function and want to set different responses to the promise resolve/reject.

This is my CacheServiceProvider.test.ts

Here I have fakePromise function and I can use jest mockImplementation method when I want to set response to the lambda.invoke().promise() 😁. If you need to change promise response , then you have to mock invoke function like invoke: () => fakePromise in the jest.mock("aws-sdk"). If this article helped you, please leave a comment. and also please leave your suggestions.

Hi guys, This is my 2nd tutorial about RESTful api with node.js
In this tutorial I explain how to setup node.js project and build node.js project
Let's start!

What we'll build?

In our application we use,
/students GET request for get list of students.
/students POST request for add new students.
/students/{id} GET request for get student information by id.
/students/{id} PATCH ,change ,update that student details.
/students{id} DELETE for delete that student form list.

First you have to install Node.js. For that follow up this link : https://nodejs.org/en/

Ok.Now we are ready to create our first application using Node.js. 😄

     So,What is RESTful API actually? REST stands for Representational State Transfer.This basically means that each unique URL is a representation of some object. This is an application program interface (API) and also RESTful APIs are stateless backends.
     A RESTful API breaks down a transaction to create a series of small modules. Each module addresses a particular underlying part of the transaction. This modularity provides developers with a lot of flexibility, but it can be challenging for developers to design from scratch. Currently, the models provided by Amazon Simple Storage Service, Cloud Data Management Interface and OpenStack Swift are the most popular.
    A RESTful API explicitly takes advantage of HTTP methodologies. They use GET to retrieve a resource; PUT to change the state of or update a resource, which can be an object, file or block; POST to create that resource; and DELETE to remove it.
   Because the calls are stateless,REST is useful in cloud applications. Stateless components can be freely redeployed if something fails, and they can scale to accommodate load changes.

Spring Boot – Deploy WAR file to separate Tomcat in maven web application.

@IonicPage({

  name: 'my-about',

  segment: 'about-page'

})

@Component({

  selector: 'page-about',

  templateUrl: 'about.html'

})

export class AboutPage { } 

Gradle is an open source build automation system and introduces a Groovy-based domain-specific language (DSL) instead of the XML for declaring the project configuration. Gradle is more feature rich than maven and more modern java build tool. If you are planning to port from maven to gradle build system, this article may help you.

Step 1: You must have gradle installed on your machine
     Gradle requires a Java JDK or JRE to be installed, version 7 or higher (to check, open command prompt and run java -version). Gradle ships with its own Groovy library, therefore Groovy does not need to be installed. Any existing Groovy installation is ignored by Gradle. Alternatively, you can set the JAVA_HOME environment variable to point to the installation directory of the desired JDK.
You can download one of the Gradle distributions from here. To check if Gradle is properly installed just type gradle –v. The output shows the Gradle version and also the local environment configuration.

Step 2: Run gradle init in the directory containing the (master) pom.xml
      gradle init automatically detects the pom.xml and creates a gradle build with the java and maven plugin loaded. Existing Maven dependencies are automatically converted and added to your gradle build file.
This will convert the maven build to a gradle build, generating one or more build.gradle files and a settings.gradle file.
For simpler maven builds, this is all we need to do. For more complex Maven builds, it may be necessary to manually add functionality on the Gradle side that couldn't be converted automatically.

What is build.gradle file?
     This build file defines a project and it’s tasks. Gradle is a general purpose build system hence this build file can perform any task.

What is settings.gradle file?
     Gradle reads the settings.gradle file to figure out which subprojects are to take part in a build. It is usually placed in the root project parallel to build.gradle.

Step 3: Run gradlew build in the directory containing build.gradle files
     This task compiles, tests, and assembles the code into a JAR file. After a few seconds, "BUILD SUCCESSFUL" indicates that the build has completed.
            
Let’s take an example:
Step 1: I run the gradle –v command into project’s root directory. I get the following output:

Now sure gradle installed successfully on your machine.

Step 2: I run the gradle init command into project’s root directory containing the (master) pom.xml. I get the following output:

Step 3: I run gradlew build in the directory containing build.gradle files.

Exaple pom.xml file:

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">

   <modelVersion>4.0.0</modelVersion>



   <groupId>com.addapps</groupId>

   <artifactId>server</artifactId>

   <version>0.0.1-SNAPSHOT</version>

   <packaging>war</packaging>

   <name>server</name>

   <description>TTGenerator web app Auth Service</description>



   <parent>

      <groupId>org.springframework.boot</groupId>

      <artifactId>spring-boot-starter-parent</artifactId>

      <version>1.4.2.RELEASE</version>

      <relativePath/> <!-- lookup parent from repository -->

   </parent>



   <properties>

     
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

     
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

      <java.version>1.8</java.version>

      <querydsl.version>4.0.4</querydsl.version>

   </properties>



   <dependencies>

      <dependency>

         <groupId>org.springframework.cloud</groupId>

         <artifactId>spring-cloud-starter-zuul</artifactId>

         <version>1.0.0.RELEASE</version>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-starter-mobile</artifactId>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-starter-security</artifactId>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-starter-web</artifactId>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-starter-websocket</artifactId>

      </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-jersey</artifactId>

      </dependency>

      <dependency>

         <groupId>mysql</groupId>

         <artifactId>mysql-connector-java</artifactId>

         <scope>runtime</scope>

         <version>5.1.17</version>

      </dependency>

      <dependency>

         <groupId>com.querydsl</groupId>

         <artifactId>querydsl-apt</artifactId>

         <version>${querydsl.version}</version>

      </dependency>

      <dependency>

         <groupId>com.querydsl</groupId>

         <artifactId>querydsl-jpa</artifactId>

         <version>${querydsl.version}</version>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-devtools</artifactId>

         <scope>runtime</scope>

      </dependency>

      <dependency>

         <groupId>org.springframework.boot</groupId>

         <artifactId>spring-boot-starter-test</artifactId>

         <scope>test</scope>

      </dependency>

      <dependency>

         <groupId>io.jsonwebtoken</groupId>

         <artifactId>jjwt</artifactId>

         <version>0.6.0</version>

      </dependency>

      <dependency>

         <groupId>org.json</groupId>

         <artifactId>json</artifactId>

      </dependency>

      <dependency>

         <groupId>com.sun.jersey</groupId>

         <artifactId>jersey-client</artifactId>

         <version>1.8</version>

      </dependency>

     
<dependency>

         <groupId>org.apache.commons</groupId>

         <artifactId>commons-io</artifactId>

         <version>1.3.2</version>

      </dependency>

      <dependency>

         <groupId>org.codehaus.jackson</groupId>

         <artifactId>jackson-mapper-asl</artifactId>

         <version>1.9.13</version>

      </dependency>

      <dependency>

         <groupId>com.google.code.gson</groupId>

         <artifactId>gson</artifactId>

         <version>2.8.0</version>

      </dependency>

      <dependency>

         <groupId>com.googlecode.json-simple</groupId>

         <artifactId>json-simple</artifactId>

         <version>1.1</version>

      </dependency>

   </dependencies>

   <dependencyManagement>

      <dependencies>

         <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-dependencies</artifactId>

            <version>Brixton.SR5</version>

            <type>pom</type>

            <scope>import</scope>

         </dependency>

      </dependencies>

   </dependencyManagement>



   <build>

      <finalName>server</finalName>

      <plugins>

         <plugin>

            <groupId>com.mysema.maven</groupId>

            <artifactId>apt-maven-plugin</artifactId>

            <version>1.1.3</version>

            <executions>

               <execution>

                  <goals>

                     <goal>process</goal>

                  </goals>

                  <configuration>

                    
<outputDirectory>${project.build.directory}/generated-sources/java</outputDirectory>

                     <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>

                  </configuration>

               </execution>

            </executions>

         </plugin>

         <plugin>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-maven-plugin</artifactId>

         </plugin>

      </plugins>

   </build>

</project>

Build.gradle file:

apply plugin: 'java'

apply plugin: 'maven'



group = 'com.addapps'

version = '0.0.1-SNAPSHOT'



description = """server"""



sourceCompatibility = 1.5

targetCompatibility = 1.5

tasks.withType(JavaCompile) {

   options.encoding = 'UTF-8'

}







repositories {



     maven { url "http://repo.maven.apache.org/maven2" }

}

dependencies {

    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-zuul', version:'1.0.0.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-mobile', version:'1.4.2.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-security', version:'1.4.2.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version:'1.4.2.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-websocket', version:'1.4.2.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa', version:'1.4.2.RELEASE'

    compile group: 'org.springframework.boot', name: 'spring-boot-starter-jersey', version:'1.4.2.RELEASE'

    compile group: 'com.querydsl', name: 'querydsl-apt', version:'4.0.4'

    compile group: 'com.querydsl', name: 'querydsl-jpa', version:'4.0.4'

    compile group: 'io.jsonwebtoken', name: 'jjwt', version:'0.6.0'

    compile group: 'org.json', name: 'json', version:'20140107'

    compile group: 'com.sun.jersey', name: 'jersey-client', version:'1.8'

    compile group: 'org.apache.commons', name: 'commons-io', version:'1.3.2'

    compile group: 'org.codehaus.jackson', name: 'jackson-mapper-asl', version:'1.9.13'

    compile group: 'com.google.code.gson', name: 'gson', version:'2.8.0'

    compile group: 'com.googlecode.json-simple', name: 'json-simple', version:'1.1'

    runtime group: 'mysql', name: 'mysql-connector-java', version:'5.1.17'

    runtime group: 'org.springframework.boot', name: 'spring-boot-devtools', version:'1.4.2.RELEASE'

    testCompile(group: 'org.springframework.boot', name: 'spring-boot-starter-test', version:'1.4.2.RELEASE') {

exclude(module: 'commons-logging')

    }

}

settings.gradle file:

rootProject.name = 'server'