Doesn't fail on empty pom; fixes gh-71

spring-cloud-release-tools-core/src/main/java/org/springframework/cloud/release/internal/pom/PomReader.java

@@ -19,6 +19,7 @@ import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.Reader;
+import java.nio.file.Files;
 
 import org.apache.maven.model.Model;
 import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
@@ -37,12 +38,19 @@ class PomReader {
 		if (file.isDirectory()) {
 			pom = new File(file,"pom.xml");
 		}
+		String fileText = "";
 		try(Reader reader = new FileReader(pom)) {
+			if (file.isFile()) {
+				fileText = new String(Files.readAllBytes(file.toPath()));
+			}
 			MavenXpp3Reader xpp3Reader = new MavenXpp3Reader();
 			return xpp3Reader.read(reader);
 		}
 		catch (XmlPullParserException | IOException e) {
-			throw new IllegalStateException("Failed to read file: "+pom.getAbsolutePath(), e);
+			if (file.isFile() && fileText.length() == 0) {
+				throw new IllegalStateException("File [" + pom.getAbsolutePath() + "] is empty", e);
+			}
+			throw new IllegalStateException("Failed to read file: " + pom.getAbsolutePath(), e);
 		}
 	}
 }

spring-cloud-release-tools-core/src/test/java/org/springframework/cloud/release/internal/pom/PomReaderTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.release.internal.pom;
 
+import java.io.EOFException;
 import java.io.File;
 import java.io.IOException;
 import java.net.URI;
@@ -38,6 +39,7 @@ public class PomReaderTests {
 	PomReader pomReader = new PomReader();
 	File springCloudReleaseProjectPom;
 	File springCloudReleaseProject;
+	File empty;
 	File licenseFile;
 
 	@Before
@@ -45,6 +47,7 @@ public class PomReaderTests {
 		URI scRelease = GitRepoTests.class.getResource("/projects/spring-cloud-release").toURI();
 		this.springCloudReleaseProject = new File(scRelease);
 		this.springCloudReleaseProjectPom = new File(scRelease.getPath(), "pom.xml");
+		this.empty = new File(GitRepoTests.class.getResource("/projects/project/empty.xml").toURI());
 		this.licenseFile = new File(scRelease.getPath(), "LICENSE.txt");
 	}
 
@@ -77,4 +80,12 @@ public class PomReaderTests {
 				.hasMessageStartingWith("Failed to read file: ")
 				.hasCauseInstanceOf(XmlPullParserException.class);
 	}
+
+	@Test
+	public void should_throw_exception_when_file_is_empty() {
+		thenThrownBy(() -> this.pomReader.readPom(this.empty))
+				.hasMessageStartingWith("File [")
+				.hasMessageContaining("] is empty")
+				.hasCauseInstanceOf(EOFException.class);
+	}
 }