camunda test with testcontainers and mockito

one-time-examples/java-camunda-test-containers/README.md

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+# Camunda 7 Unit Testing in Java with TestContainers and Service Mocking
+
+## 📌 Overview
+This project demonstrates **how to write unit tests for Camunda BPMN processes in Java** using JUnit, Mockiito and TestContainers. It sets up a testable Camunda environment, mocks external dependencies, and validates process execution.
+
+## 🚀 Getting Started
+
+### **1. Prerequisites**
+Ensure you have the following installed:
+- Maven
+- Docker (for running Camunda in TestContainers)
+
+### **2. Installation and Running Tests**
+Clone the repository and install dependencies:
+
+```sh
+mvn install
+
+```
+
+This will:
+1. Start a **Camunda TestContainer**.
+2. Deploy a BPMN process.
+3. Execute test cases using mocked dependencies.
+4. Validate process execution.
+5. Tear down the container after tests complete.
+
+## 🛠 How It Works
+
+### **1. Setting Up Camunda for Tests and Deploying the process**
+The `CamundaWorkerTest.java` file starts a **Camunda TestContainer**:
+
+```java
+        camunda = new GenericContainer<>(DockerImageName.parse("camunda/camunda-bpm-platform:7.22.0"))
+                .withExposedPorts(8080);
+        camunda.start();
+
+        baseUrl = "http://" + camunda.getHost() + ":" + camunda.getMappedPort(8080) + "/engine-rest";
+        waitForCamunda();
+
+        camundaHelper = new CamundaHelper(baseUrl);
+
+        creditServiceMock = Mockito.mock(CreditService.class);
+        ExternalTaskWorker.start(baseUrl, creditServiceMock);
+
+        camundaHelper.deployBpmnDiagram("src/test/resources/java-script-external.bpmn");
+...
+```
+
+### **2. Writing Unit Tests**
+The unit tests are executed thru CamundaWorkerTest which validates Camunda process execution:
+```java
+
+        when(creditServiceMock.getCreditScore()).thenReturn(80);
+        when(creditServiceMock.getCustomerExists()).thenReturn(false);
+
+        String processKey = "ApplicationReceived";
+        var processInstance = camundaHelper.startProcessInstance(processKey, Map.of(
+            "someInput", Map.of("value", "test", "type", "String")
+        ));
+
+        sleep(5000);
+
+        assertTrue(camundaHelper.checkElement(processInstance.id, "Add Customer", true));
+        assertTrue(camundaHelper.checkElement(processInstance.id, "Send Confirmation", true));
+        assertTrue(camundaHelper.instanceIsCompleted(processInstance.id));
+
+        verify(creditServiceMock).getCreditScore();
+        verify(creditServiceMock).getCustomerExists();
+
+```
+
+### **3. Mocking External Dependencies**
+The `CreditService.java` file is **mocked in tests**:
+
+```java
+creditServiceMock = Mockito.mock(CreditService.class);
+```
+
+## 🔥 Key Features
+✔️ Uses **Mockito** for unit testing.  
+✔️ Runs Camunda BPM in a **TestContainer** (Docker).  
+✔️ Mocks **external dependencies** (e.g., `CreditService`).  
+✔️ Validates process execution (completed, user tasks, rejections).  

one-time-examples/java-camunda-test-containers/pom.xml

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+<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://www.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.example</groupId>
+	<artifactId>java-camunda-test-containers</artifactId>
+	<version>1.0-SNAPSHOT</version>
+
+	<dependencies>
+		<!-- Camunda External Task Client (Java) -->
+		<dependency>
+			<groupId>org.camunda.bpm</groupId>
+			<artifactId>camunda-external-task-client</artifactId>
+			<version>7.20.0</version>
+		</dependency>
+
+		<!-- Testcontainers -->
+		<dependency>
+			<groupId>org.testcontainers</groupId>
+			<artifactId>testcontainers</artifactId>
+			<version>1.19.3</version>
+		</dependency>
+
+		<!-- JUnit 5 -->
+		<dependency>
+			<groupId>org.junit.jupiter</groupId>
+			<artifactId>junit-jupiter</artifactId>
+			<version>5.10.2</version>
+			<scope>test</scope>
+		</dependency>
+
+		<!-- Mockito -->
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<version>5.12.0</version>
+			<scope>test</scope>
+		</dependency>
+
+		<!-- SLF4J for logging -->
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-simple</artifactId>
+			<version>2.0.9</version>
+		</dependency>
+
+		<dependency>
+			<groupId>javax.xml.bind</groupId>
+			<artifactId>jaxb-api</artifactId>
+			<version>2.3.1</version>
+		</dependency>
+		<dependency>
+			<groupId>org.glassfish.jaxb</groupId>
+			<artifactId>jaxb-runtime</artifactId>
+			<version>2.3.1</version>
+		</dependency>
+
+		<dependency>
+			<groupId>com.squareup.okhttp3</groupId>
+			<artifactId>okhttp</artifactId>
+			<version>4.12.0</version>
+		</dependency>
+
+
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-compiler-plugin</artifactId>
+				<version>3.10.1</version>
+				<configuration>
+					<source>17</source>
+					<target>17</target>
+				</configuration>
+			</plugin>
+			<plugin>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>3.0.0-M5</version>
+      </plugin>
+		</plugins>
+	</build>
+</project>

one-time-examples/java-camunda-test-containers/src/main/java/com/example/worker/CreditService.java

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+package com.example.worker;
+
+import java.util.Random;
+
+public class CreditService {
+    private final Random random = new Random();
+
+    public int getCreditScore() {
+        return 0 + random.nextInt(100); // Range: 0-100
+    }
+
+    public boolean getCustomerExists() {
+        return random.nextBoolean();
+    }
+}

one-time-examples/java-camunda-test-containers/src/main/java/com/example/worker/ExternalTaskWorker.java

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+
+package com.example.worker;
+
+import java.util.Map;
+import java.util.logging.Logger;
+
+import org.camunda.bpm.client.ExternalTaskClient;
+
+public class ExternalTaskWorker {
+
+	private static final Logger LOGGER = Logger.getLogger("ExternalTaskWorker");
+
+	public static void start(String baseUrl, CreditService creditService) {
+		ExternalTaskClient client = ExternalTaskClient
+									.create()
+									.baseUrl(baseUrl)
+									.asyncResponseTimeout(10000)
+									.build();
+
+		client.subscribe("credit-score")
+		.lockDuration(1000)
+		.handler((externalTask, externalTaskService) -> {
+
+			LOGGER.info("✔ credit-score triggered");
+
+			int creditScore = creditService.getCreditScore();
+			boolean customerExists = creditService.getCustomerExists();
+
+			LOGGER.info("✔ Credit Score: " + creditScore);
+			LOGGER.info("✔ Customer Exists: " + customerExists);
+
+			externalTaskService.complete(externalTask,
+					Map.of("creditScore", creditScore, "customerExists", customerExists));
+		})
+		.open();
+
+
+		client.subscribe("add-customer")
+		.lockDuration(1000)
+		.handler((externalTask, externalTaskService) -> {
+
+			LOGGER.info("✔ add-customer triggered");
+
+			boolean customerExists = externalTask.getVariable("customerExists");
+
+			LOGGER.info("customerExists" + customerExists);
+
+			if (customerExists) {
+				externalTaskService.handleBpmnError(externalTask, "CustomerExists","customer allready exist");
+			}else {
+				externalTaskService.complete(externalTask,
+						Map.of("messageSend", true));
+			}
+
+
+
+		})
+		.open();
+
+		client.subscribe("send-confirmation")
+		.lockDuration(1000)
+		.handler((externalTask, externalTaskService) -> {
+
+			LOGGER.info("✔ send-confirmation triggered");
+			externalTaskService.complete(externalTask,
+					Map.of("messageSend", true));
+		})
+		.open();
+
+
+		client.subscribe("send-rejection")
+		.lockDuration(1000)
+		.handler((externalTask, externalTaskService) -> {
+
+			LOGGER.info("✔ send-rejection triggered");
+			externalTaskService.complete(externalTask,
+					Map.of("rejected", true));
+		})
+		.open();
+
+
+	}
+}