Compare 2 versions of a .NET assembly?

Question

How to compare 2 versions of a compiled .NET assembly to see changes between the 2 versions? I have a library not well-documented and I need to know what has been changed between the old version and the new version.

Answer 1

In addition to Reflector, you can use NDepend to perform this task. Please note that this is a commercial software, but the site offers a free trial. Here's an online tutorial on how one can use NDepend to compare two assemblies.

Answer 2

The tool NDepend offers many features to handle .NET code diff. Disclaimer: I am one of the developer of the tool.

The panel Search by Change is dedicated to browse assemblies code diff. Notice that:

• You can plug to NDepend any code diff tool used by the menu Compare older and newer version of source file
• If you don't have the source code, only the raw assemblies, there is the option Compare older and newer version disassembled with Reflector

Notice also in the screenshot that a CQLinq code query is generated to browse the diff.

from m in Application.Methods 
where m.CodeWasChanged() 
select new { m, m.NbLinesOfCode }

Many others default diff queries and rules are proposed by default, that will let you browse .NET code diff in a smart way.

• Types that used to be 100% covered but not anymore
• API Breaking Changes: Methods
• Avoid making complex methods even more complex
• Avoid decreasing code coverage by tests of types
• From now, all types added or refactored should respect basic quality principles
• Avoid transforming an immutable type into a mutable one
• Heuristic to find types moved from one namespace or assembly to another