Polish "Add jarmode tools command to print the SBOM"

See gh-51505

loader/spring-boot-jarmode-tools/src/main/java/org/springframework/boot/jarmode/tools/SbomCommand.java

@@ -73,14 +73,15 @@ class SbomCommand extends Command {
 
 	private String getSbomLocation(JarFile jarFile) throws IOException {
 		Manifest manifest = jarFile.getManifest();
-		if (manifest != null) {
-			String location = manifest.getMainAttributes().getValue(SBOM_LOCATION_ATTRIBUTE);
-			if (location != null) {
-				return location;
-			}
+		if (manifest == null) {
+			throw new JarModeErrorException("No manifest found in the jar");
 		}
-		throw new JarModeErrorException(
-				"No SBOM found in the jar; the manifest has no '%s' attribute".formatted(SBOM_LOCATION_ATTRIBUTE));
+		String location = manifest.getMainAttributes().getValue(SBOM_LOCATION_ATTRIBUTE);
+		if (location == null) {
+			throw new JarModeErrorException(
+					"No SBOM found in the jar; the manifest has no '%s' attribute".formatted(SBOM_LOCATION_ATTRIBUTE));
+		}
+		return location;
 	}
 
 	private void writeSbom(InputStream in, PrintStream out, Map<Option, @Nullable String> options) throws IOException {

loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/SbomCommandTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.jarmode.tools;
 
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -24,6 +25,8 @@ import java.io.PrintStream;
 import java.nio.file.Files;
 import java.util.ArrayDeque;
 import java.util.jar.Manifest;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
 
 import org.junit.jupiter.api.Test;
 
@@ -63,6 +66,13 @@ class SbomCommandTests extends AbstractJarModeTests {
 			.withMessage("No SBOM found in the jar; the manifest has no 'Sbom-Location' attribute");
 	}
 
+	@Test
+	void shouldFailWhenManifestIsMissing() throws IOException {
+		File archive = createArchiveWithoutManifest();
+		assertThatExceptionOfType(JarModeErrorException.class).isThrownBy(() -> run(archive))
+			.withMessage("No manifest found in the jar");
+	}
+
 	@Test
 	void shouldFailWhenSbomEntryIsMissing() throws IOException {
 		Manifest manifest = createManifest("Sbom-Location: " + SBOM_LOCATION);
@@ -133,6 +143,15 @@ class SbomCommandTests extends AbstractJarModeTests {
 		return createArchive(manifest, SBOM_LOCATION, SBOM_RESOURCE);
 	}
 
+	private File createArchiveWithoutManifest() throws IOException {
+		File file = new File(this.tempDir, "no-manifest.jar");
+		try (ZipOutputStream zip = new ZipOutputStream(new FileOutputStream(file))) {
+			zip.putNextEntry(new ZipEntry("some-file.txt"));
+			zip.closeEntry();
+		}
+		return file;
+	}
+
 	private byte[] getResourceContent(String resource) throws IOException {
 		try (InputStream stream = getClass().getResourceAsStream(resource)) {
 			assertThat(stream).as("Resource '%s'", resource).isNotNull();