7 Steps to Write Your Own Custom Rule using FXCOP

</Rules>

Step 2

The first thing is to reference and import the FXCOP SDK. So add a reference to the FxCopSdk.DLL. You can find FxCopSdk.dll where FxCop is installed.

Once you have added a reference, you need to import the DLL in the class file.

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.FxCop.Sdk;

Step 3

For defining custom rule, you need to inherit from the 'BaseIntrospectionRule' class of FxCop. So below is the custom class 'ClsCheck' which inherits from 'BaseIntrospectionrule' class. The constructor of 'ClsCheck' is very important. We are basically calling the parent constructor where we need to pass the class name and the XML file. So we have passed the 'clsCheck' class and the 'Connection.XML' file name. We also have to override the 'Check' method. The 'Check' method is called when every method is parsed. If there are any issues, we need to return back a problemcollection array which will be displayed in the FXCOP UI.

public class clsCheck : BaseIntrospectionRule
{
public clsCheck(): base("clsCheck", "MyRules.Connection", typeof(clsCheck).Assembly) { }
public override ProblemCollection Check(Member member)
{
..........
}

}

Step 4

So the first thing is we convert the member into the Method object. We have defined two Boolean variables, one which specifies that the connection object has been opened and the second that the connection object has been closed.

Method method = member as Method;
bool boolFoundConnectionOpened = false;
bool boolFoundConnectionClosed = false;
Instruction objInstr = null;

Step 5

Every method has an instruction collection which is nothing but the actual code. So we loop through all instructions and check if we find the string of SQLConnection. If yes, we set the Boolean value of the found connection to true. If we find that we have found 'Dbconnection.close', we set the found connection closed to true.

for (int i = 0; i < method.Instructions.Count; i++)
{
objInstr = method.Instructions[i];
if (objInstr.Value != null)
{
if (objInstr.Value.ToString().Contains("System.Data.SqlClient.SqlConnection"))
{
boolFoundConnectionOpened = true;
}
if (boolFoundConnectionOpened)
{
if(objInstr.Value.ToString().Contains("System.Data.Common.DbConnection.Close"))
{
boolFoundConnectionClosed = true;
}
}
}
}

Step 6

Now the last thing. We check if the connection is opened, was it closed? If not, then we get the message of the connection.xml file and add it to the problems collection. This problems collection is returned to the FXCOP to display it.

if((boolFoundConnectionOpened)&&(boolFoundConnectionClosed ==false))
{
Resolution resolu = GetResolution(new string[] { method.ToString() });
Problems.Add(new Problem(resolu));
}

return Problems;

Step 7

Once you have compiled the DLL, add the DLL as rules and run the analyze project button. Below is the project which was analyzed and the 'objConnection' object which was open and was never closed.

public void addInvoiceDetails(int intInvoiceid_fk,
int intCustomerId,
int intProductid_fk,
double dblTotalAmount,
double dblTotalAmountPaid)
{
SqlConnection objConnection = new SqlConnection();
}

You can see in the output how the method name is displayed with the resolution read from the connection.xml file.

At the top of this article you can get the Source Code.