To enable code coverage for X++ code in your test automation, a few things have to be setup. Typically, more tweaking is needed since you will likely be using some platform/foundation/appsuite objects and code, and don't want code coverage to show up for those. Additionally, the X++ compiler generates some extra IL to support certain features, which can be ignored. Unfortunately there is one feature that may throw off your results, we'll talk about this further down.
One important note: Code Coverage is a feature of Visual Studio Enterprise and is not available in lower SKUs. See this comparison chart under Testing Tools | Code Coverage.
To get started, you can download the sample RunSettings file here: CodeCoverage You will need to update this file to include your own packages (="modules" in IL terminology). At the top of the file, you will find the following XML:
You will need to replace the "MyPackageName" with the name of your package. You can add multiple lines here and use wildcards, of course. You could add Dynamics.AX.* but that would then include any and all packages under test (including Application Suite, for example). This example also shows how to exclude a package explicitly, for example in this case the test package itself. If you have multiple packages to exclude and include, you would enter it this way:
To enable code coverage in Visual Studio, open the Test menu, select Test Settings and Select Test Settings File. Select your settings file. You can then run code coverage from menu Test > Analyze Code Coverage and then selecting All Tests or Selected Tests (this is your selection in the Test Explorer window). You can open the code coverage results and double click any of the lines - which will open the code and highlight the coverage.
To enable code coverage in the automated build, edit your build definition. Click on the Execute Tests task, and find the Run Settings File parameter. If you have a generic run settings file, you can place it in the C:\DynamicsSDK folder on the build VM, and point to it here (full path). Optionally, if you have a settings file specific for certain packages or build definitions, you can be more flexible here. For example, if the run settings file is in source control in the Metadata folder, you can point this argument to "$(Build.SourcesDirectory)\Metadata\MySettings.runsettings".
The biggest issue with this is the extra IL code that our compiler generates, namely the pre- and post-handler code that is generated. This is placed inside any method, and is thus evaluated by code coverage even though your X++ source doesn't contain this code. As such most methods will never get 100% coverage. If a method has the [Hookable(false)] attribute (which makes the X++ compiler not add the extra IL code), or if the method actually has pre/post handlers, the coverage will be fine. Note that Chain-of-Command logic that the compiler generates is nicely filtered out.