Refactor SUB handlers

X86DisassemblerTests/InstructionTests/SubRm8Imm8Tests.cs

@@ -1,6 +1,24 @@
-namespace X86DisassemblerTests.InstructionTests;
+using X86Disassembler.X86;
+
+namespace X86DisassemblerTests.InstructionTests;
 
 public class SubRm8Imm8Tests
 {
-    
+    [Fact]
+    public void SubRm8Imm8_Decodes_Correctly()
+    {
+        // Arrange
+        // SUB BL, 0x42
+        byte[] codeBuffer = new byte[] { 0x80, 0xeb, 0x42 };
+        var decoder = new Disassembler(codeBuffer, 0x1000);
+        
+        // Act
+        var instructions = decoder.Disassemble();
+
+        // Assert
+        Assert.Single(instructions);
+        Assert.NotNull(instructions[0]);
+        Assert.Equal("sub", instructions[0].Mnemonic);
+        Assert.Equal("bl, 0x42", instructions[0].Operands);
+    }
 }