separate unit test for decimal sbc

src/cpu.rs

@@ -780,7 +780,7 @@ mod tests {
     use num::range_inclusive;
 
 	#[test]
-	fn decimal_mode_test() {
+	fn decimal_add_test() {
 		let mut cpu = CPU::new();
 		cpu.registers.status.or(Status::PS_DECIMAL_MODE);
 		
@@ -804,7 +804,13 @@ mod tests {
         assert_eq!(cpu.registers.status.contains(Status::PS_ZERO), true);
         assert_eq!(cpu.registers.status.contains(Status::PS_NEGATIVE), false);
         assert_eq!(cpu.registers.status.contains(Status::PS_OVERFLOW), true);
+	}
 
+	#[test]
+	fn decimal_subtract_test() {
+		let mut cpu = CPU::new();
+		cpu.registers.status.or(Status::PS_DECIMAL_MODE);
+		
 		cpu.subtract_with_carry(0x48);
         assert_eq!(cpu.registers.accumulator as u8, 0x52);
         assert_eq!(cpu.registers.status.contains(Status::PS_CARRY), true);