Merge branch '4.0.x'

Closes gh-49427

core/spring-boot-docker-compose/build.gradle

@@ -32,6 +32,8 @@ dependencies {
 
 	dockerTestImplementation(project(":test-support:spring-boot-docker-test-support"))
 
+	dockerTestRuntimeOnly("org.testcontainers:testcontainers")
+
 	testImplementation(project(":core:spring-boot-test"))
 	testImplementation(project(":test-support:spring-boot-test-support"))
 	testImplementation("ch.qos.logback:logback-classic")

test-support/spring-boot-docker-test-support/src/main/java/org/springframework/boot/testsupport/container/DisabledIfDockerUnavailableCondition.java

@@ -21,6 +21,9 @@ import org.junit.jupiter.api.extension.ExecutionCondition;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.testcontainers.DockerClientFactory;
 
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+
 /**
  * An {@link ExecutionCondition} that disables execution if Docker is unavailable.
  *
@@ -30,12 +33,17 @@ import org.testcontainers.DockerClientFactory;
  */
 class DisabledIfDockerUnavailableCondition implements ExecutionCondition {
 
+	private static final boolean TESTCONTAINERS_PRESENT = ClassUtils.isPresent("org.testcontainers.DockerClientFactory",
+			DisabledIfDockerUnavailableCondition.class.getClassLoader());
+
 	private static final String SILENCE_PROPERTY = "visibleassertions.silence";
 
 	private static final ConditionEvaluationResult ENABLED = ConditionEvaluationResult.enabled("Docker available");
 
 	@Override
 	public ConditionEvaluationResult evaluateExecutionCondition(ExtensionContext context) {
+		Assert.isTrue(TESTCONTAINERS_PRESENT, "Testcontainers is required when using @DisabledIfDockerUnavailable."
+				+ " Add a dependency on org.testcontainers:testcontainers");
 		String originalSilenceValue = System.getProperty(SILENCE_PROPERTY);
 		try {
 			DockerClientFactory.instance().client();