Adding some simple unit tests.

src/main/java/io/github/applecommander/applesingle/AppleSingle.java

@@ -123,7 +123,7 @@ public class AppleSingle {
 		int resourceForkOffset = prodosFileInfoOffset + 8;
 		int dataForkOffset = resourceForkOffset + (hasResourceFork ? resourceFork.length : 0);
 		
-		writeFileHeader(outputStream);
+		writeFileHeader(outputStream, entries);
 		writeHeader(outputStream, 3, realNameOffset, realName.length());
 		writeHeader(outputStream, 11, prodosFileInfoOffset, 8);
 		if (hasResourceFork) writeHeader(outputStream, 2, resourceForkOffset, resourceFork.length);
@@ -145,17 +145,20 @@ public class AppleSingle {
 		}
 	}
 	
-	private void writeFileHeader(OutputStream outputStream) throws IOException {
-		ByteBuffer buf = ByteBuffer.allocate(24).order(ByteOrder.BIG_ENDIAN);
-		buf.putLong(MAGIC_NUMBER);
-		buf.putLong(VERSION_NUMBER);
+	private void writeFileHeader(OutputStream outputStream, int numberOfEntries) throws IOException {
+		final byte[] filler = new byte[16];
+		ByteBuffer buf = ByteBuffer.allocate(26).order(ByteOrder.BIG_ENDIAN);
+		buf.putInt(MAGIC_NUMBER);
+		buf.putInt(VERSION_NUMBER);
+		buf.put(filler);
+		buf.putShort((short)numberOfEntries);
 		outputStream.write(buf.array());
 	}
 	private void writeHeader(OutputStream outputStream, int entryId, int offset, int length) throws IOException {
 		ByteBuffer buf = ByteBuffer.allocate(12).order(ByteOrder.BIG_ENDIAN);
-		buf.putLong(entryId);
-		buf.putLong(offset);
-		buf.putLong(length);
+		buf.putInt(entryId);
+		buf.putInt(offset);
+		buf.putInt(length);
 		outputStream.write(buf.array());
 	}
 	private void writeRealName(OutputStream outputStream) throws IOException {
@@ -165,7 +168,7 @@ public class AppleSingle {
 		ByteBuffer buf = ByteBuffer.allocate(8).order(ByteOrder.BIG_ENDIAN);
 		buf.putShort((short)prodosFileInfo.access);
 		buf.putShort((short)prodosFileInfo.fileType);
-		buf.putLong(prodosFileInfo.fileType);
+		buf.putInt(prodosFileInfo.fileType);
 		outputStream.write(buf.array());
 	}
 	private void writeResourceFork(OutputStream outputStream) throws IOException {

src/test/java/io/github/applecommander/applesingle/AppleSingleTest.java

@@ -0,0 +1,58 @@
+package io.github.applecommander.applesingle;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+import org.junit.Test;
+
+public class AppleSingleTest {
+	private static final String AS_HELLO_BIN = "/hello.applesingle.bin";
+	
+	@Test
+	public void testSampleFromCc65() throws IOException {
+		AppleSingle as = AppleSingle.read(getClass().getResourceAsStream(AS_HELLO_BIN)); 
+		
+		assertNull(as.getRealName());
+		assertNull(as.getResourceFork());
+		assertNotNull(as.getDataFork());
+		assertNotNull(as.getProdosFileInfo());
+		
+		ProdosFileInfo info = as.getProdosFileInfo();
+		assertEquals(0xc3, info.getAccess());
+		assertEquals(0x06, info.getFileType());
+		assertEquals(0x0803, info.getAuxType());
+	}
+
+	@Test
+	public void testCreateAndReadAppleSingle() throws IOException {
+		final byte[] dataFork = "testing testing 1-2-3".getBytes();
+		final String realName = "test.as";
+		
+		// Using default ProDOS info and skipping resource fork
+		AppleSingle createdAS = AppleSingle.builder()
+				.dataFork(dataFork)
+				.realName(realName)
+				.build();
+		assertNotNull(createdAS);
+		assertEquals(realName, createdAS.getRealName());
+		assertArrayEquals(dataFork, createdAS.getDataFork());
+		assertNull(createdAS.getResourceFork());
+		assertNotNull(createdAS.getProdosFileInfo());
+		
+		ByteArrayOutputStream actualBytes = new ByteArrayOutputStream();
+		createdAS.save(actualBytes);
+		assertNotNull(actualBytes);
+		
+		AppleSingle readAS = AppleSingle.read(actualBytes.toByteArray());
+		assertNotNull(readAS);
+		assertEquals(realName, readAS.getRealName());
+		assertArrayEquals(dataFork, readAS.getDataFork());
+		assertNull(readAS.getResourceFork());
+		assertNotNull(readAS.getProdosFileInfo());
+	}
+}