Added test to confirm empty bdf file on build binary

src/main/java/edu/cmu/sv/arinc838/builder/SoftwareDefinitionFileBuilder.java

@@ -179,7 +179,12 @@ public SdfFile buildXml() {
 	}
 
 	@Override
-	public int buildBinary(BdfFile file) throws IOException {
+	public int buildBinary(BdfFile file) throws IOException, IllegalArgumentException{
+
+		if (file.length() != 0){
+			throw new IllegalArgumentException();
+		}
+
 		file.seek(0);
 		// write the header
 		file.writePlaceholder(); // file size
@@ -210,7 +215,9 @@ public int buildBinary(BdfFile file) throws IOException {
 		for (int i = 0; i < size; i++) {
 			this.getFileDefinitions().get(i).buildBinary(file);
 		}
-
+
+		//calculate CRC up to this point
+
 		// write the SDF integrity def
 		file.writeSdfIntegrityDefinitionPointer();
 		this.getSdfIntegrityDefinition().setIntegrityValue(

src/main/java/edu/cmu/sv/arinc838/writer/BdfWriter.java

@@ -21,10 +21,15 @@ public class BdfWriter implements SdfWriter {
 	public String write(String path, SoftwareDefinitionFileBuilder builder)
 			throws Exception {		
 
+
 		File fileOnDisk =new File(path+builder.getBinaryFileName());
 
+
 		BdfFile file = new BdfFile(fileOnDisk);
 
+		//This file must be empty
+		file.setLength(0);
+
 		write(file, builder);
 
 		return fileOnDisk.getAbsolutePath();

src/test/java/edu/cmu/sv/arinc838/builder/SoftwareDefinitionFileBuilderTest.java

@@ -324,7 +324,7 @@ public void testBuildBinaryWritesSoftwareDefinition() throws IOException {
 		InOrder order = inOrder(file, swDescription, thdBuilder,
 				thdBuilderLast, fdBuilder, fdBuilderLast, sdfInteg, lspInteg);
 
-		when(file.length()).thenReturn(14L);
+		when(file.length()).thenReturn(0L, 14L);
 		int bytesWritten = swDefFileBuilder.buildBinary(file);
 		assertEquals(bytesWritten, 14L);
 
@@ -348,8 +348,9 @@ public void testBuildBinaryWritesSoftwareDefinition() throws IOException {
 		order.verify(fdBuilder, times(2)).buildBinary(file);
 		order.verify(fdBuilderLast).buildBinary(file);
 
+		order.verify(file)
 		order.verify(file).writeSdfIntegrityDefinitionPointer();
-		// TODO actually calculate the CRC
+
 		order.verify(sdfInteg).setIntegrityValue(
 				Converter.hexToBytes("0000000A"));
 		order.verify(sdfInteg).buildBinary(file);
@@ -504,4 +505,17 @@ public void testInitializeXmlClearsTargetHardwareDefinitions(){
 
 		assertEquals(builder.getTargetHardwareDefinitions().size(), swDefFile.getThwDefinitions().size());		
 	}
+
+
+	@Test (expectedExceptions = IllegalArgumentException.class)
+	public void testBinaryFileIsEmptyPriorToBuild() throws FileNotFoundException, IOException{
+		BdfFile bdf = new BdfFile(File.createTempFile("tmp", "BDF"));
+		bdf.write(3);
+
+		SoftwareDefinitionFileBuilder builder = new SoftwareDefinitionFileBuilder();
+
+		builder.buildBinary(bdf);
+
+	}
+
 }