Improve error when Docker Compose file not found

Fixes gh-35383

spring-boot-project/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/core/DockerComposeFile.java

@@ -109,8 +109,8 @@ public final class DockerComposeFile {
 	 */
 	public static DockerComposeFile of(File file) {
 		Assert.notNull(file, "File must not be null");
-		Assert.isTrue(file.exists(), () -> "'%s' does not exist".formatted(file));
+		Assert.isTrue(file.exists(), () -> "Docker Compose file '%s' does not exist".formatted(file));
-		Assert.isTrue(file.isFile(), () -> "'%s' is not a file".formatted(file));
+		Assert.isTrue(file.isFile(), () -> "Docker compose file '%s' is not a file".formatted(file));
 		return new DockerComposeFile(file);
 	}
 

spring-boot-project/spring-boot-docker-compose/src/main/java/org/springframework/boot/docker/compose/lifecycle/DockerComposeLifecycleManager.java

@@ -43,6 +43,7 @@ import org.springframework.core.log.LogMessage;
  * @author Moritz Halbritter
  * @author Andy Wilkinson
  * @author Phillip Webb
+ * @author Scott Frederick
  * @see DockerComposeListener
  */
 class DockerComposeLifecycleManager {
@@ -124,7 +125,12 @@ class DockerComposeLifecycleManager {
 	protected DockerComposeFile getComposeFile() {
 		DockerComposeFile composeFile = (this.properties.getFile() != null)
 				? DockerComposeFile.of(this.properties.getFile()) : DockerComposeFile.find(this.workingDirectory);
-		logger.info(LogMessage.format("Found Docker Compose file '%s'", composeFile));
+		if (composeFile == null) {
+			File dir = (this.workingDirectory != null) ? this.workingDirectory : new File(".");
+			throw new IllegalStateException("No Docker Compose file found in directory '%s'"
+				.formatted(dir.toPath().toAbsolutePath().toString()));
+		}
+		logger.info(LogMessage.format("Using Docker Compose file '%s'", composeFile));
 		return composeFile;
 	}
 

spring-boot-project/spring-boot-docker-compose/src/test/java/org/springframework/boot/docker/compose/lifecycle/DockerComposeLifecycleManagerTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.docker.compose.lifecycle;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Paths;
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -42,6 +43,7 @@ import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.util.FileCopyUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.BDDMockito.then;
@@ -54,6 +56,7 @@ import static org.mockito.Mockito.never;
  * @author Moritz Halbritter
  * @author Andy Wilkinson
  * @author Phillip Webb
+ * @author Scott Frederick
  */
 class DockerComposeLifecycleManagerTests {
 
@@ -113,6 +116,24 @@ class DockerComposeLifecycleManagerTests {
 		then(this.dockerCompose).should(never()).hasDefinedServices();
 	}
 
+	@Test
+	void startWhenComposeFileNotFoundThrowsException() {
+		DockerComposeLifecycleManager manager = new DockerComposeLifecycleManager(new File("."),
+				this.applicationContext, null, this.shutdownHandlers, this.properties, this.eventListeners,
+				this.skipCheck, this.serviceReadinessChecks);
+		assertThatIllegalStateException().isThrownBy(manager::start)
+			.withMessageContaining(Paths.get(".").toAbsolutePath().toString());
+	}
+
+	@Test
+	void startWhenComposeFileNotFoundAndWorkingDirectoryNullThrowsException() {
+		DockerComposeLifecycleManager manager = new DockerComposeLifecycleManager(null, this.applicationContext, null,
+				this.shutdownHandlers, this.properties, this.eventListeners, this.skipCheck,
+				this.serviceReadinessChecks);
+		assertThatIllegalStateException().isThrownBy(manager::start)
+			.withMessageContaining(Paths.get(".").toAbsolutePath().toString());
+	}
+
 	@Test
 	void startWhenInTestDoesNotStart() {
 		given(this.skipCheck.shouldSkip(any(), any())).willReturn(true);