Create a new unit test for #1274 and propose a fix

src/main/java/spoon/support/compiler/jdt/JDTBasedSpoonCompiler.java

@@ -415,16 +415,18 @@ protected void buildModel(CompilationUnitDeclaration[] units) {
 		JDTTreeBuilder builder = new JDTTreeBuilder(factory);
 		unitLoop:
 		for (CompilationUnitDeclaration unit : units) {
-			final String unitPath = new String(unit.getFileName());
-			for (final CompilationUnitFilter cuf : compilationUnitFilters) {
-				if (cuf.exclude(unitPath)) {
-					// do not traverse this unit
-					continue unitLoop;
+			if (!unit.isEmpty()) {
+				final String unitPath = new String(unit.getFileName());
+				for (final CompilationUnitFilter cuf : compilationUnitFilters) {
+					if (cuf.exclude(unitPath)) {
+						// do not traverse this unit
+						continue unitLoop;
+					}
+				}
+				unit.traverse(builder, unit.scope);
+				if (getFactory().getEnvironment().isCommentsEnabled()) {
+					new JDTCommentBuilder(unit, factory).build();
 				}
-			}
-			unit.traverse(builder, unit.scope);
-			if (getFactory().getEnvironment().isCommentsEnabled()) {
-				new JDTCommentBuilder(unit, factory).build();
 			}
 		}
 	}

src/test/java/spoon/test/api/APITest.java

@@ -54,7 +54,7 @@ public void testBasicAPIUsage() throws Exception {
 		// this test shows a basic usage of the Launcher API without command line
 		// and asserts there is no exception
 		Launcher spoon = new Launcher();
-		spoon.setArgs(new String[] {"--output-type", "nooutput" });
+		spoon.setArgs(new String[] {"--compile", "--output-type", "compilationunits" });
 		spoon.addInputResource("src/test/resources/spoon/test/api");
 		spoon.run();
 		Factory factory = spoon.getFactory();

src/test/java/spoon/test/support/ResourceTest.java

@@ -1,6 +1,8 @@
 package spoon.test.support;
 
+import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 
 import java.io.File;
@@ -30,14 +32,17 @@ public void testFileSystemFolder() throws Exception {
 		FileSystemFolder fileSystemFolder = new FileSystemFolder(new File(dir));
 
 		// there is one file in api
-		assertEquals(1, fileSystemFolder.getAllFiles().size());
-		assertEquals(1, fileSystemFolder.getAllJavaFiles().size());
+		assertEquals(2, fileSystemFolder.getAllFiles().size());
+		assertEquals(2, fileSystemFolder.getAllJavaFiles().size());
 
 		String entry = "src/test/resources/spoon/test/api/Foo.java";
 		FileSystemFile file = new FileSystemFile(new File(entry));
 
-		// this file in Foo.java
-		assertEquals(file, fileSystemFolder.getAllFiles().get(0));
+		String entry1 = "src/test/resources/spoon/test/api/CommentedClass.java";
+		FileSystemFile file1 = new FileSystemFile(new File(entry1));
+
+		assertThat(fileSystemFolder.getAllFiles().contains(file), is(true));
+		assertThat(fileSystemFolder.getAllFiles().contains(file1), is(true));
 	}
 
 	@Test
@@ -52,10 +57,10 @@ public void testVirtualFolder() throws Exception {
 		folder.addFolder(fileSystemFolder);
 		folder.addFolder(fileSystemFolder2);
 
-		assertEquals(3, folder.getAllFiles().size());
+		assertEquals(4, folder.getAllFiles().size());
 
 		// the README is not a Java file
-		assertEquals(2, folder.getAllJavaFiles().size());
+		assertEquals(3, folder.getAllJavaFiles().size());
 	}
 
 	@Test

src/test/resources/spoon/test/api/CommentedClass.java

@@ -0,0 +1,7 @@
+//package spoon.test.api.testclasses;
+//
+///**
+// * Created by urli on 03/05/2017.
+// */
+//public class CommentedClass {
+//}