Mailsac provides a REST API to fetch and read email. The REST API also allows you to reserve an email address that can forward messages to another mailsac email address, Slack, WebSocket, or webhook

This article describes how to integrate with Mailsac using Java and the JUnit testing framework. The JavaMail API will be used to send email via SMTP.

What is JUnit?

JUnit is a unit testing framework for the Java programming language. The latest version of the framework, JUnit 5, requires Java 8 or above. It supports testing using a command-line interface, build automation tools, and IDEs.

JUnit can be used to test individual components of code to ensure that each unit is performing as intended.

Setting Up the Environment

Depending on the environment, there are multiple ways to run tests. Testing using the command and JUnit are included in this example.

Testing Using Command-Line

Running tests from the command-line requires the ConsoleLauncher application(junit-platform-console-standalone-1.7.2.jar). JUnit ConsoleLauncher is published in the Maven Central repository under the junit-platform-console-standalone directory.

1. Navigate to the Maven Central directory
2. Download junit-platform-console-standalone-1.7.2.jar.
3. Create a directory for the project: mkdir mailsac-tests.
4. Move the jar file you downloaded into the directory mailsac-tests.
5. Create a directory inside mailsac-tests: mkdir test.
   
   Note: mailsac-tests/test will contain your source code.

JUnit Testing Introduction

This code example shows basic usage of the JUnit testing framework.

Inside the directory mailsac-tests/test, create a java file: touch TestClass.java.

Add the following code snippet to ./mailsac-tests/test/TestClass.java

import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

@DisplayName("tests truth")
class TestClass {

    @Test
    @DisplayName("true equals true")
    void trueEqualsTrue() {
        // The assertTrue method asserts that the supplied condition is true.
        // static void assertTrue(condition)
        assertTrue(true);
    }

    @Test
    @DisplayName("false equals false")
    void falseEqualsFalse() {
        // The assertEquals method asserts that expected and actual are equal.
        // static void assertEquals(expected, actual)
        assertEquals(false, false);
    }

}

@Test Denotes that a method is a test.

@DisplayName Declares a custom display name for the test class or test method.

Refer to JUnit annotations and JUnit Assertions for further reading.

Running JUnit Tests From The Command-Line

1. Inside the directory mailsac-tests, compile the test:javac -verbose -cp junit-platform-console-standalone-1.7.2.jar -d test test/TestClass.java.
2. Then run:java -jar junit-platform-console-standalone-1.7.2.jar --class-path test --scan-class-path.

The output should appear similar to this:

╷
├─ JUnit Jupiter ✔
│  └─ tests truth ✔
│     ├─ false equals false ✔
│     └─ true equals true ✔
└─ JUnit Vintage ✔

Test run finished after 92 ms
[         3 containers found      ]
[         0 containers skipped    ]
[         3 containers started    ]
[         0 containers aborted    ]
[         3 containers successful ]
[         0 containers failed     ]
[         2 tests found           ]
[         0 tests skipped         ]
[         2 tests started         ]
[         0 tests aborted         ]
[         2 tests successful      ]
[         0 tests failed          ]

The first section of output shows the name of the unit test (tests truth) and the test names (true equals true and false equals false). The checkmark next to the test name indicates it was successful.

The second section of output shows a summary of the test results.

Testing Using Build Tools

Testing from build automation tools, like Maven, is another option. In many ways, using build tools is the best option. For instance, they provide a standard directory layout that encourages industry standard naming conventions.

Maven abstracts many underlying mechanisms allowing developers to run a single command for validating, compiling, testing, packaging, verifying, installing, and deploying code.

This section will describe how to set up Maven for building, managing, and testing a project.

1. Navigate to the Apache Maven download page and follow the installation instructions. If you have Homebrew you can install Maven using the command: brew install maven.
2. After installing Maven, run on the command-line to initialize the directory mailsac-integration-test-java as a maven managed project:

mvn archetype:generate \
    -DgroupId=com.mailsac.api \
    -DartifactId=mailsac-integration-test-java \
    -DarchetypeArtifactId=maven-archetype-quickstart \
    -DarchetypeVersion=1.4 \
    -DinteractiveMode=false

3. Navigate into the directory: cd mailsac-integration-test-java
4. Update the <dependencies> and <build> sections of pom.xml with the following xml.

<!-- ... -->
<dependencies>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-api</artifactId>
    <version>5.7.2</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-engine</artifactId>
    <version>5.7.2</version>
    <scope>test</scope>
  </dependency>
</dependencies>
<!-- ... -->
<build>
  <pluginManagement>
    <!-- ... -->
    <plugins>
      <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.22.2</version>
      </plugin>
      <plugin>
        <artifactId>maven-failsafe-plugin</artifactId>
        <version>2.22.2</version>
      </plugin>
    </plugins>
    <!-- ... -->
  </pluginManagement>
</build>
<!-- ... -->

5. Edit the AppTest.java file: $EDITOR src/test/java/com/mailsac/api/AppTest.java

package com.mailsac.api;

import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;

class TestClass {

    @Test
    void trueEqualsTrue() {
        // The assertTrue method asserts that the supplied condition is true.
        // static void assertTrue(condition)
        assertTrue(true);
    }

    @Test
    void falseEqualsFalse() {
        // The assertEquals method asserts that expected and actual are equal.
        // static void assertEquals(expected, actual)
        assertEquals(false, false);
    }

}

6. In the directory mailsac-integration-test-java, run mvn clean package. This command deletes the folder target , packages the project into a new target folder, and runs a unit test.
7. Tests can be manually run using the command mvn test in the mailsac-integration-test-java directory.The output should appear similar to:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.mailsac.api.TestClass
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 s - in com.mailsac.api.TestClass
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0

Mailsac Java Integration Test

This section describes how to leverage Mailsac and JUnit to test mail delivery. Emails will be sent to Mailsac using SMTP and email delivery will be validated with JUnit.

There are 3 additional libraries that will be used:

• The Unirest library will to used to send REST requests to the Mailsac API
• Jackson to parse JSON
• JavaMail API to send email via SMTP

Integration Test Example

1. With Maven, add the following dependencies to pom.xml
   If you are not using Maven include the JAR files in the classpath:

https://mvnrepository.com/artifact/com.mashape.unirest/unirest-java/1.4.9

https://mvnrepository.com/artifact/com.sun.mail/javax.mail/1.6.2

https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind/2.12.5

<!-- ... -->
<dependencies>
  <!-- ... -->
  <dependency>
    <groupId>com.mashape.unirest</groupId>
    <artifactId>unirest-java</artifactId>
    <version>1.4.9</version>
  </dependency>
  <dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.2</version>
  </dependency>
  <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.5</version>
  </dependency>
</dependencies>
<!-- ... -->

2. Edit the AppTest.java file: $EDITOR src/test/java/com/mailsac/api/AppTest.java
   
   Import the required modules

package com.mailsac.api;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;
import com.mashape.unirest.http.exceptions.UnirestException;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Date;
import java.util.Properties;

import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

3. Acquire a Mailsac API key and configure SMTP sending. Export these parameters as environment variables:

export MAILSAC_API_KEY=your_mailsac_key;
export [email protected]
export [email protected]
export SMTP_USERNAME=your_smtp_username
export SMTP_PASSWORD=your_smtp_password
export SMTP_HOST=smtp.example.com

public class AppTest {
    // MAILSAC_API_KEY environment variable. Generated by mailsac. See
    // https://mailsac.com/api-keys
    static String mailsacAPIKey = "";
    // MAILSAC_TO_ADDRESS environment variable. Who you're sending an email to.
    static String mailsacToAddress = "";
    // SMTP_FROM_ADDRESS environment variable. Necessary if you are sending
    // through out.mailsac.com (unlikely - you most likely will replace
    // sendMail() below.
    static String fromAddress = "";
    // SMTP_USERNAME environment variable. Required for authenticated SMTP sending
    static String smtpUserName = "";
    // SMTP_PASSWORD environment variable. Required for authenticated SMTP sending
    static String smtpPassword = "";
    // SMTP_HOST environment variable. Hostname of your SMTP server
    static String smtpHost = "";
    // SMTP_PORT environment variable. Port used for SMTP sending
    static int smtpPort = 587;

    @BeforeAll
    static void setup() throws Exception {
        mailsacAPIKey = System.getenv().get("MAILSAC_API_KEY");
        mailsacToAddress = System.getenv().get("MAILSAC_TO_ADDRESS");
        fromAddress = System.getenv().get("SMTP_FROM_ADDRESS");
        smtpUserName = System.getenv().get("SMTP_USERNAME");
        smtpPassword = System.getenv().get("SMTP_PASSWORD");
        smtpHost = System.getenv().get("SMTP_HOST");
        if (System.getenv().get("SMTP_PORT") != null) {
            Integer.parseInt(System.getenv().get("SMTP_PORT"));
        }
        if (mailsacAPIKey == null || mailsacToAddress == null || fromAddress == null) {
            throw new Exception("Missing environment variable setup!");
        }
        if (smtpUserName == null || smtpPassword == null || smtpHost == null) {
            throw new Exception("Missing SMTP environment variables");
        }
        System.out.println(mailsacAPIKey);
        System.out.println(mailsacToAddress);
        System.out.println(fromAddress);
    }
}

4. Add a purgeInbox() method which makes a DELETE request to api/addresses/{email}/messages/(messageId}.
   
   This section of code should be added to the existing AppTest class.

public class AppTest {
  //...
 @BeforeEach
 @AfterEach
 // purgeInbox cleans up all messages in the inbox before and after running each
 // test,
 // so there is a clean state.
 void purgeInbox() throws UnirestException, JsonProcessingException {
     HttpResponse<String> response = Unirest
             .get(String.format("https://mailsac.com/api/addresses/%s/messages", mailsacToAddress))
             .header("Mailsac-Key", mailsacAPIKey)
             .asString();

     // Parse JSON
     ObjectMapper objectMapper = new ObjectMapper();
     Object[] messagesArray = objectMapper.readValue(response.getBody(), Object[].class);

     for (int i = 0; i < messagesArray.length; i++) {
         JsonNode m = objectMapper.convertValue(messagesArray[i], JsonNode.class);
         String id = m.get("_id").asText();
         System.out.printf("Purging inbox message %s\n", id);
         Unirest.delete(String.format("https://mailsac.com/api/addresses/%s/messages/%s", mailsacToAddress, id))
                 .header("Mailsac-Key", mailsacAPIKey)
                 .asString();
     }
 }
  //...
}

5. Implement a sendMail() method which sends an email. This section will likely likely be different depending on your use case. For example, you may be sending emails via your web application or via an email campaign.

public class AppTest {
    //...
    static void sendMail(String subject, String textMessage, String htmlMessage)
            throws UnsupportedEncodingException, MessagingException {
        Session session = Session.getDefaultInstance(new Properties());
        javax.mail.Transport transport = session.getTransport("smtp");
        MimeMessage msg = new MimeMessage(session);

        // set message headers
        msg.addHeader("Content-type", "text/HTML; charset=UTF-8");
        msg.addHeader("format", "flowed");
        msg.addHeader("Content-Transfer-Encoding", "8bit");

        msg.setFrom(fromAddress);
        msg.setReplyTo(InternetAddress.parse(fromAddress));
        msg.setSubject(subject, "UTF-8");
        msg.setText(textMessage, "UTF-8");
        msg.setContent(htmlMessage, "text/html");

        msg.setSentDate(new Date());

        msg.setRecipients(Message.RecipientType.TO, mailsacToAddress);
        msg.saveChanges();
        System.out.println("Email message is ready to send");
        transport.connect(smtpHost, smtpPort, smtpUserName, smtpPassword);
        transport.sendMessage(msg, msg.getAllRecipients());

        System.out.println("Email sent successfully");
    }
    // ...
}

6. Add test. Use a for loop to check if the message was received by scanning the recipient inbox periodically. If the recipient inbox is not empty, and a message was found, the test verifies the message content:
   
   This test uses the Mailsac API endpoint /api/addresses/{email}/messages which lists all messages in an inbox.
   

public class AppTest {
    //...
    @Test
    void checkEmailWithLink() throws MessagingException, UnirestException, IOException, InterruptedException {
        sendMail("Hello!", "Check out https://example.com", "Check out <a href='https://example.com'>My website</a>");
        // Check inbox for the message up to 10x, waiting 5 seconds between checks.
        found: {
            for (int i = 0; i < 10; i++) {
                // Send request to fetch a JSON array of email message objects from mailsac
                HttpResponse<String> response = Unirest
                        .get(String.format("https://mailsac.com/api/addresses/%s/messages", mailsacToAddress))
                        .header("Mailsac-Key", mailsacAPIKey)
                        .asString();

                // Parse JSON
                ObjectMapper objectMapper = new ObjectMapper();
                Object[] messagesArray = objectMapper.readValue(response.getBody(), Object[].class);

                System.out.printf("Fetched %d messages from Mailsac for address %s\n", messagesArray.length,
                        mailsacToAddress);
                eachMessage: {
                    for (int m = 0; m < messagesArray.length; m++) {
                        // Convert object into JSON to fetch a field
                        JsonNode thisMessage = objectMapper.convertValue(messagesArray[m], JsonNode.class);

                        // After a message is found, the JSON object is checked to see if the link was
                        // sent correctly
                        assertTrue(thisMessage.get("links").toString().contains("https://example.com"),
                                "Missing / Incorrect link in email");

                        System.out.printf("Message id %s contained the correct link\n",
                                thisMessage.get("_id").asText());

                        return; // end the tests
                    }
                }

                System.out.println("Message not found yet, waiting 5 secs");
                Thread.sleep(5000);
            }

            // Fail the test if we haven't reached assertTrue above
            fail("Never received expected message!");
        }
    }
    // ..
}

7. At this point, the code is complete. Package the project: mvn clean package. This will also run a test.
   
   Subsequent changes to the source file do not require you to run mvn clean package again. Instead, run mvn test.
   
   The output should appear similar to this:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.mailsac.api.AppTest
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 9.148 s s - in com.mailsac.api.AppTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

GitHub Repository

If you encounter any difficulties, git clone https://github.com/mailsac/mailsac-integration-test-java. Make edits as necessary, and run mvn package.

Alternatively, if your tests fail because of error codes when making requests to the Mailsac API, please refer to the API Specification for further reading.

Next Steps

The Mailsac API Specification has generated code examples in Java + Unirest for making requests. It also has code examples in other languages.

This example can be adjusted to get all private email addresses for an account and purge their inboxes if necessary.

Please visit our forums if you have any questions!

When you send to any inbox @mailsac.com, if a + plus symbol is included, we remove that symbol and everything after it.

jeff+12345asdf@mailsac.com

will be delivered to

[email protected]

Many email services including Gmail, iCloud and Fastmail support stripping the + plus symbol and everything after it in the local-part of the address (everything before the @ symbol).

Plus-addressing has long been a useful feature to segment user accounts across services. At Mailsac we offer a variety of disposable email and forwarding utilities that are designed for software QA engineers and developers. Things like forwarding all messages in a domain to a single address, or automatically routing email to webhooks or slack, are really easy – may not even require DNS setup.

All the code shown in this article is published at https://github.com/mailsac/mailsac-integration-test-examples

Integration tests identify errors between systems. These tests can be slow to run because of the interactions between multiple systems.

Mailsac can facilitate integration testing between web apps and transactional email services.

This article explains how to use WebSockets to make your email integration tests faster and simpler than with REST API polling.

Explaining the differences: REST APIs vs WebSockets

A REST API call uses a HTTP request for creating, reading, updating, and deleting objects. The HTTP connection between the client and server is short lived. An example of this is the List Messages In Inbox endpoint. The endpoint will return JSON formatted information about email messages in a Mailsac Inbox. Each time a client checks for new messages a new HTTP connection will be used.

A WebSocket is a persistent connection between a client and server providing full-duplex communication. By reusing an established connection there is no need to poll the REST API for changes, instead data can be pushed to the client in real time. WebSockets often listen on port 80/443 but does not use HTTP, except for the initial connection handshake.

REST API Polling Examples

The examples below use the “old way” – hit the Mailsac REST API and “poll” the inbox for new messages.

• Using Selenium To Test Account Email Signups
• Write Integration Tests Using Mailsac
• Delivery Confirmation Test
• Email Validation with Selenium

Polling is reliable and familiar for API programmers.

However, this approach can result in significant delays between when the email was received by Mailsac and when the test checks for a new message. Every few seconds, you ask the server if there are new messages.

Using a Web Socket Instead of Polling

What if the server could notify you that there are new messages? That’s where WebSockets come in.

This code example uses Node.js and Mocha test framework. Portions of the code example are presented below.

Steps to Validate Email Contents Using a WebSocket

Here’s how you can get notified of a new email message:

1. Establish a WebSocket connection with Mailsac
2. Send an email using SMTP to a private Mailsac address
3. Receive content of the email over the established WebSocket
4. Validate the content of the email
5. Send a second email using SMTP to a private Mailsac addrress
6. Receive content of second email over the established WebSocket
7. Validate the content of the second email
8. Delete both email messages
9. Close WebSocket connection

Test Configuration

This test requires several variables be defined. They can be set by editing the script or by setting environment variables.

const mailsacAPIKey = process.env.MAILSAC_API_KEY || ''; // Generated by mailsac. See https://mailsac.com/api-keys
const mailsacToAddress = process.env.MAILSAC_TO_ADDRESS || ''; // Mailsac email address where the email will be sent
const smtpUserName = process.env.SMTP_USER || ''; // Username for smtp server authentication
const smtpPassword = process.env.SMTP_PASSWORD || ''; // Password for smtp server authentication
const smtpHost = process.env.SMTP_HOST || ''; // hostname of the smtp server
const smtpPort = process.env.SMTP_PORT || 587; // port the smtp is listening on

Setup: Configure Mailsac Address for WebSocket Forwarding

The Mailsac address used in this example needs to have WebSocket forwarding enabled on it. Any messages sent to the email address will be forwarded by the Mailsac WebSocket server.

To enable WebSocket forwarding the Mailsac address must be private. Private addresses have additional features such as forwarding to Slack, forwarding to a Webhook, and forwarding to a WebSocket. Select the “Settings” button next to the email address you want to configure from Manage Owned Email Addresses. Select the check box to “Enabled forwarding all incoming email via web socket” and select “Save Settings”.

1. Establish WebSocket Connection

The NPM package ws is a WebSocket client used to connect to the Mailsac WebSocket service.

The Websocket connection to Mailsac is established on lines 12-14. The ws package will only reject a Promise if it fails to connect to the WebSocket server due to a network error. Wrapping the connection in a Promise allows for additional validations.

The Mailsac WebSocket server will send the message ({"status":200,"msg":"Listening","addresses":["[email protected]"]}) after the initial connection. In lines 16-26 the initial message is parsed and checked for value of the property status. The Promise is rejected if the initial status message is not received or does not have a status code of 200.

const mailsacAPIKey = process.env.MAILSAC_API_KEY || ''; // Generated by mailsac. See https://mailsac.com/api-keys
const mailsacToAddress = process.env.MAILSAC_TO_ADDRESS || ''; // Mailsac email address where the email will be sent

describe("send email to mailsac", function () {

  // Open websocket waiting for email. This websocket will be reused for tests in this file.
  before(() => {
    return new Promise((resolve, reject) => {
      ws = new WebSocket(
        `wss://sock.mailsac.com/incoming-messages?key=${mailsacAPIKey}&addresses=${mailsacToAddress}`
      );
      let wsMessage; // message response object
      ws.on("message", (msg) => {
        try {
          wsMessage = JSON.parse(msg);
        } catch {
          assert(wsMessage, "Failed to parse JSON from websocket message");
        }
        if (wsMessage.status != 200) {
          reject(new Error("connection error: " + wsMessage.error));
          return;
        }
        resolve(wsMessage);
      });
      ws.on("error", (err) => {
        reject(err);
      });
    });
  });
});

2. Send email using SMTP

The NPM package nodemailer is used to send a test email via SMTP.

The connection to the STMP server is configured in lines 4-10. Most SMTP servers will require authentication.

The email’s to, from, subject, and content are set in lines 14-18. The email will be sent to the address defined in the configuration at the beginning of the script or the environment variable MAILSAC_TO_ADDRESS. The email will include a link to the website https://example.com.

  it("sends email with link to example.com website", async () => {
    // create a transporter object using the default SMTP transport
    const transport = nodemailer.createTransport({
      host: smtpHost,
      port: smtpPort,
      auth: {
        user: smtpUserName,
        pass: smtpPassword,
      },
    });
    // send mail using the defined transport object
    const result = await transport.sendMail({
      from: smtpUserName, // sender address
      to: mailsacToAddress, // recipient address
      subject: "Hello!",
      text: "Check out https://example.com",
      html: "Check out <a href https://example.com>My website</a>",
    });
  });

3. Receive Message via WebSocket

Once the email arrives, Mailsac will send a JSON formatted version of the email on the WebSocket established earlier in this example. ws.on("message", (msg) => { ... } is a function that will run when new message is sent by the WebSocket server. The msg is parsed as JSON. Then the Promise will resolve if the message has a to property. The existence of the to property is checked to make sure the message sent by the WebSocket server was an email and not a status message. The await keyword will cause the test to wait until a message is sent over the WebSocket or the test times out.

const wsMessage = await new Promise((resolve) => {
  ws.on("message", (msg) => {
    const wsResponse = JSON.parse(msg);
    if (wsResponse.to) {
      resolve(wsResponse);
    }
  });
});

Example JSON formatted message

{

    "status": 200,
    "email": 

{

    "text": "string",
    "body": "string",
    "raw": "string",
    "headers": { },
    "_id": "m3phnJ2ag3example-0",
    "from": 

[

    {
        "name": "string",
        "address": "string"
    }

],
"to": 
[

    {
        "name": "string",
        "address": "string"
    }

],
"cc": 
[

    {
        "name": "string",
        "address": "string"
    }

],
"bcc": 
[

    {
        "name": "string",
        "address": "string"
    }

],
"subject": "string",
"savedBy": "string",
"originalInbox": "string",
"inbox": "[email protected]",
"domain": "example.com",
"received": "1985-04-12T23:20:50.52Z",
"size": 0,
"attachments": 
[

    "5ea9c924627e68f988c9c7ca44340892"

],
"ip": "string",
"via": "string",
"folder": "inbox",
"labels": 
[

    "string"

],
"read": true,
"rtls": true,
"links": 

        [
            "string"
        ],
        "spam": 0.345
    }

}

4. Validate Content of the Email

The assert package is used to validate the contents of the email. The subject and text properties are assigned to new variables. assert.equal(subject, "Hello!"); will cause an exception if subject is not equal to Hello!. The test framework Mocha will interpret this as a failure and the test will fail. Likewise, if the variable email_text is not Check out https://example.com the test will fail.

const subject = wsMessage.subject;
const email_text = wsMessage.text;
assert.equal(subject, "Hello!");
assert.equal(email_text, "Check out https://example.com");

5-7. Send Another Email and Validate Its Content

The reason to send a second email is to demonstrate that the Mailsac WebSocket connection can be reused. This second test will reuse the WebSocket connection established (variable name ws) in the before() block in step 1. The only difference between the first and second test is the content of the email.

// Sends a second email reusing the websocket.
it("sends email with link to unsubscribe.example.com website", async () => {
  const transport = nodemailer.createTransport({
    host: smtpHost,
    port: smtpPort,
    auth: {
      user: smtpUserName,
      pass: smtpPassword,
    },
  });
  const result = await transport.sendMail({
    from: smtpUserName, // sender address
    to: mailsacToAddress, // recipient address
    subject: "Unsubscribe",
    text: "Click the link to unsubscribe https://unsubscribe.example.com",
    html: "Check out <a href https://example.com>My website</a>",
  });

  console.log("Sent email with messageId: ", result.messageId);

  const wsMessage = await new Promise((resolve) => {
    ws.on("message", (msg) => {
      const wsResponse = JSON.parse(msg);
      if (wsResponse.to) {
        resolve(wsResponse);
      }
    });
  });

  assert(wsMessage, "Never received messages!");

  const subject = wsMessage.subject;
  const email_text = wsMessage.text;
  assert.equal(subject, "Unsubscribe");
  assert.equal(
    email_text,
    "Click the link to unsubscribe https://unsubscribe.example.com"
  );
});

8. Delete Emails to Prevent Leaky Tests

An after() block will run after the tests have completed. The REST API Endpoint – Delete All Messages In An In Inbox is called to delete the test emails. By deleting all the test emails, it prevents these emails from being fetched in another test, which could impact the results of another test. It is best practice to clean up tests after they ran.

The NPM package supertest is used to make the REST call to delete the messages. Virtually any HTTP client library could be used to do this. Feel free to use the HTTP client library you feel most comfortable with.

afte(() =>
  request("https://mailsac.com")
    .delete(`/api/addresses/${mailsacToAddress}/messages`)
    .set("Mailsac-Key", mailsacAPIKey)
    .expect(204)
);

9. Close WebSocket Connection

An after() block is used to close the WebSocket connection after all the tests have completed. It is best practice to close all connections on the termination of the test.

// close websocket after all tests finish
after(() => ws.close());

Next Steps

The use of WebSockets helps speed up tests and uses API calls more efficiently.

See the WebSocket Test Page to see a WebSocket in action in your browser. This page includes a basic code example usage ofoffor a WebSocket client and is a great starting point before divining into integration testing using WebSockets.

If you have questions about this example or the Mailsac WebSocket service please post on https://forum.mailsac.com

Mailsac has a REST API that can be leveraged to validate emails are being received with the correct contents. This can be useful for web applications that send customized emails to customers.

This example will demonstrate how to send an email via an SMTP server and validate the email was received. The code used in this example is available on GitHub.

Setup Project Directory

Node version 12 or greater is required for this example due to the use of async and await.

Begin by creating a directory for the project.

mkdir mailsac-tests
cd mailsac-tests
npm init # enter project information, for test command use 'mocha'

Verify package.json looks something like this. The most important part is "scripts": { "test": "mocha" }

{
  "name": "mailsac-integration-tests",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "directories": {
    "test": "test"
  },
  "scripts": {
    "test": "mocha"
  },
  "author": "",
  "license": "ISC"
}

Installing a Test Framework

The test framework for this example is Mocha. It is a test framework for Javascript applications. A test framework will allow us to write tests against our code.

Setup Test Directory

These directions are inspired by the Mocha Getting Started Guide.

cd mailsac-tests
npm install --save-dev mocha
mkdir test
$EDITOR test/test.js # or open with your favorite editor

Write a Test to Test For Truth

This section is for people who are new to Mocha and test frameworks. Skip ahead if you know how to write tests.

Mocha follows a Behavior Driven Development (BDD) model of testing. This allows for human readable descriptions of software behavior. The first line of the code shows exactly what the following tests will test (ie describe("tests truth"). The following lines state the expected outcome of the test (ie it(true equals true).

This test uses Node’s built in assert. The first parameter passed to assert() is checked for true. If it is true, the assert passes. If the value is false, it throws an exception. In this example, we assert that true is true and that false is equal to false.

Create a describe block in test/test.js

describe("tests truth", () => {
    it('true equals true', function() {
        assert(true); // assert checks for truth
    });
    it('false equals false', () => {
        // assert equal checks the first and second parameter are equal
        assert.equal(false,false);
    });
})

This code can be run and the test should pass. Run the test with npm test . Confirm the test passed.

Congratulations! You have a working test.

Write an Integration Test

In this example, an email will be sent to Mailsac using the ubiquitous Javascript SMTP library NodeMailer, then the test framework will call Mailsac to validate that the email was received.

Install Dependencies

There are a few Node modules that will make sending an email and interacting with the Mailsac REST API easier. NodeMailer will be used to send the email via SMTP. SuperTest will be used to call the Mailsac API.

npm install

Integration Test Example

Back in the text editor, open / create the file test.js in the test folder. Copy and paste the following code or see GitHub for the complete example.

Import required modules

const assert = require("assert");
const nodemailer = require("nodemailer");
const request = require("supertest");

Configure SMTP settings and Mailsac Credentials

// Generated by mailsac. See https://mailsac.com/api-keys
const mailsacAPIKey = "";
// Mailsac email address where the email will be sent
const mailsacToAddress = "[email protected]";
// Username for smtp server authentication
const smtpUserName = "";
// Password for smtp server authentication
const smtpPassword = "";
// hostname of the smtp server
const smtpHost = "";
// port the smtp is listening on
const smtpPort = 587;

Create wait Function

The test will contact the Mailsac API multiple times while waiting for the email to arrive. This function will be used later in a for loop while waiting for the email to arrive.

const wait = (millis) => new Promise((resolve) => setTimeout(resolve, millis));

Add a Describe block with Timeout and Test Cleanup

The describe callback describes in human readable terms what the test is going to do. The increased timeout is required because the default timeout for Mocha is 2 seconds. The test email will likely not arrive that quickly. The afterEach section is used to delete all messages after the test runs. This prevents a leaky test.

describe("send email to mailsac", function () {
  this.timeout(50000); // test can take a long time to run. This increases the default timeout for mocha

  /* delete all messages in the inbox after the test runs to prevent leaky tests.
       This requires the inbox to private, which is a paid feature of Mailsac.
       The afterEach section could be omitted if using a public address
    */
  afterEach(() =>
    request("https://mailsac.com")
      .delete(`/api/addresses/${mailsacToAddress}/messages`)
      .set("Mailsac-Key", mailsacAPIKey)
      .expect(204)
  );
});

Add it block and NodeMailer Configuration

The it interface describes what the test will do "sends email with link to example.com website“. The transport variable is used to store the configuration of the SMTP server.

result = await transport.sendMail({… Attempts to send the email and capture the result.

describe("send email to mailsac", function () {
...

  it("sends email with link to example.com website", async () => {
    // create a transporter object using the default SMTP transport
    const transport = nodemailer.createTransport({
      host: smtpHost,
      port: smtpPort,
      auth: {
        user: smtpUserName,
        pass: smtpPassword,
      },
    });
    // send mail using the defined transport object
    const result = await transport.sendMail({
      from: smtpUserName, // sender address
      to: mailsacToAddress, // recipient address
      subject: "Hello!",
      text: "Check out https://example.com",
      html: "Check out <a href https://example.com>My website</a>",
    });

    // logs the messageId of the email, confirming the
    // email was submitted to the smtp server
    console.log("Sent email with messageId: ", result.messageId);
});

Add Loop to Check Mail

This section of code uses a for loop and a http library (supertest) to check if the message has arrived at Mailsac. The test uses the Mailsac API endpoint /api/addresses/{email}/messages which lists all messages in an inbox.

describe("send email to mailsac", function () {
...

  it("sends email with link to example.com website", async () => {
...
    // Check email in the inbox 10x, waiting 5 secs in between. Once we find mail, abort the loop.
    let messages = [];
    for (let i = 0; i < 10; i++) {
      // returns the JSON array of email message objects from mailsac.
      const res = await request("https://mailsac.com")
        .get(`/api/addresses/${mailsacToAddress}/messages`)
        .set("Mailsac-Key", mailsacAPIKey);

      messages = res.body;
      if (messages.length > 0) {
        break;
      }
      await wait(4500);
    }
  });
});

Add Assertion to Check for Link in the Message

assert is used twice. First, to check to see if any messages were fetched from the Mailsac inbox. This checks the length of the messages array to see if any messages were received. The second assert is used to check for a link to http://example.com .

describe("send email to mailsac", function () {
  // ...
  it("sends email with link to example.com website", async () => {
    // ...
    let messages = [];
    for (let i = 0; i < 10; i++) {
      // ... await get messages from mailsac
    }
    assert(messages.length, "Never received messages!");

    // After a message is retrieved from mailsac, the JSON object is checked to see if the link was parsed from the email and it is the correct link
    const link = messages[0].links.find((l) => "https://example.com");
    assert(link, "Missing / Incorrect link in email");
  });
});

Run Test

At this point the test code is complete and can be run using npm test. If all went well the following output is written to the console.

npm test

Run Test Using GitHub Repository

If you are having some trouble with the tests, I recommend downloading the code from GitHub and running it.

git clone https://github.com/mailsac/mailsac-integration-test-examples.git
cd mailsac-integration-test-examples
npm install
$EDITOR test/test.js # or open with your favorite editor

Edit the test.js and fill in your SMTP settings and Mailsac API key

const mailsacAPIKey = ""; // Generated by mailsac. See https://mailsac.com/api-keys
const mailsacToAddress = "[email protected]"; // Mailsac email address where the email will be sent
const smtpUserName = ""; // Username for smtp server authentication
const smtpPassword = ""; // Password for smtp server authentication
const smtpHost = ""; // hostname of the smtp server
const smtpPort = 587; // port the smtp is listening on

Run test running the command npm test in your terminal.

Next Steps

The example above can be used as part of your team’s quality assurance process. A real world example would be validating password reset links to customers. This test could be used to validate that when a customer requests a password reset an email is sent to them containing the correct password reset link.

If you have any questions about this example or want to talk about other implementations reach out to our community at https://forum.mailsac.com .