Add test module for CLI

settings.gradle

@@ -11,4 +11,5 @@ include(
         ":streams-bootstrap-test",
         ":streams-bootstrap-large-messages",
         ":streams-bootstrap-cli",
+        ":streams-bootstrap-cli-test",
 )

streams-bootstrap-cli-test/build.gradle.kts

@@ -0,0 +1,6 @@
+description = "Utils for testing your Kafka Streams Application"
+
+dependencies {
+    api(project(":streams-bootstrap-test"))
+    api(project(":streams-bootstrap-cli"))
+}

streams-bootstrap-cli-test/lombok.config

@@ -0,0 +1,3 @@
+# This file is generated by the 'io.freefair.lombok' Gradle plugin
+config.stopBubbling = true
+lombok.addLombokGeneratedAnnotation = true

streams-bootstrap-cli-test/src/main/java/com/bakdata/kafka/TestApplicationHelper.java

@@ -0,0 +1,65 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 bakdata
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.bakdata.kafka;
+
+import com.bakdata.fluent_kafka_streams_tests.TestTopology;
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public final class TestApplicationHelper {
+
+    private final @NonNull TestEnvironment environment;
+
+    public ConfiguredStreamsApp<? extends StreamsApp> createConfiguredApp(
+            final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.configure(app);
+        app.prepareRun();
+        return app.createConfiguredApp();
+    }
+
+    public <K, V> TestTopology<K, V> createTopology(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        final ConfiguredStreamsApp<? extends StreamsApp> configuredApp = this.createConfiguredApp(app);
+        final TestTopologyFactory testTopologyFactory = this.createTestTopologyFactory();
+        return testTopologyFactory.createTopology(configuredApp);
+    }
+
+    public <K, V> TestTopology<K, V> createTopologyExtension(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        final ConfiguredStreamsApp<? extends StreamsApp> configuredApp = this.createConfiguredApp(app);
+        final TestTopologyFactory testTopologyFactory = this.createTestTopologyFactory();
+        return testTopologyFactory.createTopologyExtension(configuredApp);
+    }
+
+    public void configure(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        app.setSchemaRegistryUrl(this.environment.getSchemaRegistryUrl());
+    }
+
+    private TestTopologyFactory createTestTopologyFactory() {
+        return new TestTopologyFactory(this.environment);
+    }
+
+}

streams-bootstrap-cli-test/src/main/java/com/bakdata/kafka/TestApplicationRunner.java

@@ -0,0 +1,119 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 bakdata
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.bakdata.kafka;
+
+import static java.util.Collections.emptyList;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+import java.lang.Thread.UncaughtExceptionHandler;
+import java.util.List;
+import lombok.Getter;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor
+public final class TestApplicationRunner {
+
+    private final @NonNull String bootstrapServers;
+    private final @NonNull TestEnvironment environment;
+
+    public void run(final KafkaStreamsApplication<? extends StreamsApp> app, final String[] args) {
+        final String[] newArgs = this.setupArgs(args, emptyList());
+        final Thread thread = new Thread(() -> KafkaApplication.startApplicationWithoutExit(app, newArgs));
+        thread.start();
+    }
+
+    public int clean(final KafkaStreamsApplication<? extends StreamsApp> app, final String[] args) {
+        final String[] newArgs = this.setupArgs(args, List.of("clean"));
+        return KafkaApplication.startApplicationWithoutExit(app, newArgs);
+    }
+
+    public int reset(final KafkaStreamsApplication<? extends StreamsApp> app, final String[] args) {
+        final String[] newArgs = this.setupArgs(args, List.of("reset"));
+        return KafkaApplication.startApplicationWithoutExit(app, newArgs);
+    }
+
+    public Thread run(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.prepareExecution(app);
+        final Thread thread = new Thread(app);
+        final UncaughtExceptionHandler handler = new CapturingUncaughtExceptionHandler();
+        thread.setUncaughtExceptionHandler(handler);
+        thread.start();
+        return thread;
+    }
+
+    public void clean(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.prepareExecution(app);
+        app.clean();
+    }
+
+    public void reset(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.prepareExecution(app);
+        app.reset();
+    }
+
+    public void prepareExecution(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.configure(app);
+        app.onApplicationStart();
+    }
+
+    public ConsumerGroupVerifier verify(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        this.configure(app);
+        final KafkaEndpointConfig endpointConfig = app.getEndpointConfig();
+        final KafkaTestClient testClient = new KafkaTestClient(endpointConfig);
+        try (final ConfiguredStreamsApp<? extends StreamsApp> configuredApp = app.createConfiguredApp()) {
+            final String uniqueAppId = configuredApp.getUniqueAppId();
+            return new ConsumerGroupVerifier(uniqueAppId, testClient::admin);
+        }
+    }
+
+    public KafkaTestClient newTestClient() {
+        return new KafkaTestClient(KafkaEndpointConfig.builder()
+                .bootstrapServers(this.bootstrapServers)
+                .schemaRegistryUrl(this.environment.getSchemaRegistryUrl())
+                .build());
+    }
+
+    public void configure(final KafkaStreamsApplication<? extends StreamsApp> app) {
+        app.setBootstrapServers(this.bootstrapServers);
+        app.setSchemaRegistryUrl(this.environment.getSchemaRegistryUrl());
+    }
+
+    private String[] setupArgs(final String[] args, final Iterable<String> command) {
+        final Builder<String> argBuilder = ImmutableList.<String>builder()
+                .add(args)
+                .add("--bootstrap-servers", this.bootstrapServers);
+        if (this.environment.getSchemaRegistryUrl() != null) {
+            argBuilder.add("--schema-registry-url", this.environment.getSchemaRegistryUrl());
+        }
+        final List<String> newArgs = argBuilder
+                .addAll(command)
+                .build();
+        return newArgs.toArray(new String[0]);
+    }
+
+}

streams-bootstrap-cli/build.gradle.kts

@@ -18,6 +18,7 @@ dependencies {
     testImplementation(group = "org.mockito", name = "mockito-core", version = mockitoVersion)
     testImplementation(group = "org.mockito", name = "mockito-junit-jupiter", version = mockitoVersion)
     testImplementation(testFixtures(project(":streams-bootstrap-core")))
+    testImplementation(project(":streams-bootstrap-cli-test"))
     testImplementation(group = "com.ginsberg", name = "junit5-system-exit", version = "1.1.2")
     val confluentVersion: String by project
     testImplementation(group = "io.confluent", name = "kafka-streams-avro-serde", version = confluentVersion)

streams-bootstrap-cli/src/main/java/com/bakdata/kafka/KafkaApplication.java

@@ -257,36 +257,36 @@ public final CleanableApp<CR> createCleanableApp() {
         return cleanableApp;
     }
 
-    /**
-     * Create a new {@code ConfiguredApp} that will be executed according to the given config.
-     *
-     * @param app app to configure.
-     * @param configuration configuration for app
-     * @return {@code ConfiguredApp}
-     */
-    protected abstract CA createConfiguredApp(final A app, AppConfiguration<T> configuration);
-
     /**
      * Called before starting the application, e.g., invoking {@link #run()}
      */
-    protected void onApplicationStart() {
+    public void onApplicationStart() {
         // do nothing by default
     }
 
     /**
      * Called before running the application, i.e., invoking {@link #run()}
      */
-    protected void prepareRun() {
+    public void prepareRun() {
         // do nothing by default
     }
 
     /**
      * Called before cleaning the application, i.e., invoking {@link #clean()}
      */
-    protected void prepareClean() {
+    public void prepareClean() {
         // do nothing by default
     }
 
+    /**
+     * Create a new {@code ConfiguredApp} that will be executed according to the given config.
+     *
+     * @param app app to configure.
+     * @param configuration configuration for app
+     * @return {@code ConfiguredApp}
+     */
+    protected abstract CA createConfiguredApp(final A app, AppConfiguration<T> configuration);
+
     private void startApplication() {
         Runtime.getRuntime().addShutdownHook(new Thread(this::close));
         this.onApplicationStart();

streams-bootstrap-cli/src/main/java/com/bakdata/kafka/KafkaStreamsApplication.java

@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2024 bakdata
+ * Copyright (c) 2025 bakdata
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -154,7 +154,7 @@ public final ConfiguredStreamsApp<T> createConfiguredApp(final T app,
      * Called before cleaning the application, i.e., invoking {@link #clean()} or {@link #reset()}
      */
     @Override
-    protected void prepareClean() {
+    public void prepareClean() {
         super.prepareClean();
     }
 

streams-bootstrap-cli/src/test/java/com/bakdata/kafka/integration/RunStreamsAppTest.java

@@ -24,13 +24,15 @@
 
 package com.bakdata.kafka.integration;
 
+import static com.bakdata.kafka.TestEnvironment.withoutSchemaRegistry;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.bakdata.kafka.KafkaStreamsApplication;
 import com.bakdata.kafka.KafkaTest;
 import com.bakdata.kafka.KafkaTestClient;
 import com.bakdata.kafka.SenderBuilder.SimpleProducerRecord;
 import com.bakdata.kafka.SimpleKafkaStreamsApplication;
+import com.bakdata.kafka.TestApplicationRunner;
 import com.bakdata.kafka.TestTopologyFactory;
 import com.bakdata.kafka.test_applications.Mirror;
 import java.nio.file.Path;
@@ -53,12 +55,10 @@ void shouldRunApp() {
         final KafkaTestClient testClient = this.newTestClient();
         testClient.createTopic(output);
         try (final KafkaStreamsApplication<?> app = new SimpleKafkaStreamsApplication<>(Mirror::new)) {
-            app.setBootstrapServers(this.getBootstrapServers());
             app.setKafkaConfig(TestTopologyFactory.createStreamsTestConfig(this.stateDir));
             app.setInputTopics(List.of(input));
             app.setOutputTopic(output);
-            // run in Thread because the application blocks indefinitely
-            new Thread(app).start();
+            new TestApplicationRunner(this.getBootstrapServers(), withoutSchemaRegistry()).run(app);
             testClient.send()
                     .with(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class)
                     .with(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class)

streams-bootstrap-cli/src/test/java/com/bakdata/kafka/integration/StreamsCleanUpTest.java

@@ -25,12 +25,15 @@
 package com.bakdata.kafka.integration;
 
 
+import static com.bakdata.kafka.TestEnvironment.withoutSchemaRegistry;
+
 import com.bakdata.kafka.CloseFlagApp;
 import com.bakdata.kafka.KafkaStreamsApplication;
 import com.bakdata.kafka.KafkaTest;
 import com.bakdata.kafka.KafkaTestClient;
 import com.bakdata.kafka.SenderBuilder.SimpleProducerRecord;
 import com.bakdata.kafka.SimpleKafkaStreamsApplication;
+import com.bakdata.kafka.TestApplicationRunner;
 import com.bakdata.kafka.TestTopologyFactory;
 import com.bakdata.kafka.test_applications.WordCount;
 import com.bakdata.kafka.util.ImprovedAdminClient;
@@ -84,7 +87,7 @@ void shouldClean() {
 
             // Wait until all stream applications are completely stopped before triggering cleanup
             this.awaitClosed(app.createExecutableApp());
-            app.clean();
+            this.clean(app);
 
             try (final ImprovedAdminClient admin = testClient.admin()) {
                 this.softly.assertThat(admin.getTopicClient().exists(app.getOutputTopic()))
@@ -120,7 +123,7 @@ void shouldReset() {
 
             // Wait until all stream applications are completely stopped before triggering cleanup
             this.awaitClosed(app.createExecutableApp());
-            app.reset();
+            this.reset(app);
 
             try (final ImprovedAdminClient admin = testClient.admin()) {
                 this.softly.assertThat(admin.getTopicClient().exists(app.getOutputTopic()))
@@ -141,26 +144,37 @@ void shouldCallClose() {
             this.newTestClient().createTopic(app.getInputTopics().get(0));
             this.softly.assertThat(app.isClosed()).isFalse();
             this.softly.assertThat(app.isAppClosed()).isFalse();
-            app.clean();
+            this.clean(app);
             this.softly.assertThat(app.isAppClosed()).isTrue();
             app.setAppClosed(false);
-            app.reset();
+            this.reset(app);
             this.softly.assertThat(app.isAppClosed()).isTrue();
         }
     }
 
+    private void clean(final KafkaStreamsApplication<?> app) {
+        this.createTestRunner().clean(app);
+    }
+
+    private void reset(final KafkaStreamsApplication<?> app) {
+        this.createTestRunner().reset(app);
+    }
+
     private void runAppAndClose(final KafkaStreamsApplication<?> app) {
         this.runApp(app);
         app.stop();
     }
 
     private void runApp(final KafkaStreamsApplication<?> app) {
-        // run in Thread because the application blocks indefinitely
-        new Thread(app).start();
+        this.createTestRunner().run(app);
         // Wait until stream application has consumed all data
         this.awaitProcessing(app.createExecutableApp());
     }
 
+    private TestApplicationRunner createTestRunner() {
+        return new TestApplicationRunner(this.getBootstrapServers(), withoutSchemaRegistry());
+    }
+
     private CloseFlagApp createCloseFlagApplication() {
         final CloseFlagApp app = new CloseFlagApp();
         app.setInputTopics(List.of("input"));
@@ -196,7 +210,6 @@ private KafkaStreamsApplication<?> createWordCountApplication() {
     }
 
     private <T extends KafkaStreamsApplication<?>> T configure(final T application) {
-        application.setBootstrapServers(this.getBootstrapServers());
         application.setKafkaConfig(TestTopologyFactory.createStreamsTestConfig(this.stateDir));
         return application;
     }