Validate Code with Layer Diagrams

To make sure that code doesn't conflict with its design, you can validate code with layer diagrams in Visual Studio Ultimate and Visual Studio Premium. This can help you:

  • Find conflicts between dependencies in your code and dependencies on the layer diagram.

  • Find dependencies that might be affected by proposed changes.

    For example, you can edit the layer diagram to show potential architecture changes and then validate the code to see the affected dependencies.

  • Refactor or migrate code to a different design.

    Find code or dependencies that require work when you move the code to a different architecture.

You can validate code manually from an open layer diagram in Visual Studio or from a command prompt. You can also validate code automatically when running local builds or Team Foundation Build. See Channel 9 Video: Design and validate your architecture using layer diagrams.

Important noteImportant

You don't have to install Visual Studio on your Team Foundation Build server to run layer validation. However, if you run layer validation on a computer with different versions of Team Foundation Server and Visual Studio, Visual Studio might crash. To fix this issue, download and install the most recent update for both Visual Studio and Team Foundation Server agents.


  • Visual Studio Ultimate or Visual Studio Premium

  • A solution that has a modeling project with a layer diagram. This layer diagram must be linked to artifacts in Visual C# .NET or Visual Basic .NET projects that you want to validate. See Create Layer Diagrams from Code.

  1. On the layer diagram, select one or more layers, right-click your selection, and then click View Links.

  2. In Layer Explorer, look at the Supports Validation column. If the value is false, the item does not support validation.

You can link Web sites, Office documents, and plain text files to layers, but the validation process won't include them. Validation errors won't appear for references to projects or assemblies that are linked to separate layers when no dependencies appear between those layers. Such references are not considered dependencies unless the code uses those references.

When you drag items to the layer diagram, references to the corresponding .NET assemblies or projects are added automatically to the Layer References folder in the modeling project. This folder contains references to the assemblies and projects that are analyzed during validation. You can include other .NET assemblies and projects for validation without manually dragging them to the layer diagram.

  1. In Solution Explorer, right-click the modeling project or the Layer References folder, and then click Add Reference.

  2. In the Add Reference dialog box, select the assemblies or projects, and then click OK.

If you have an open layer diagram that is linked to solution items, you can run the Validate shortcut command from the diagram. You can also use the command prompt to run the msbuild command with the /p:ValidateArchitecture custom property set to True. For example, as you make changes in the code, perform layer validation regularly so that you can catch dependency conflicts early.

To validate code from an open layer diagram

  1. Right-click the diagram surface, and then click Validate Architecture.


    By default, the Build Action property on the layer diagram (.layerdiagram) file is set to Validate so that the diagram is included in the validation process.

    The Error List window reports any errors that occur. For more information about validation errors, see Understand and resolve layer validation errors.

  2. To view the source of each error, double-click the error in the Error List window.


    Visual Studio might show a dependency graph instead of the source of the error. This occurs when either the code has a dependency on an assembly that is not specified by the layer diagram, or the code is missing a dependency that is specified by the layer diagram. Review the dependency graph or the code to determine whether the dependency should exist. For more information about dependency graphs, see Visualize Code Dependencies on Dependency Graphs.

  3. To manage errors, see Manage validation errors.

To validate code at the command prompt

  1. Open the Visual Studio command prompt.

  2. Choose one of the following:

    • To validate code against a specific modeling project in the solution, run MSBuild with the following custom property.

      msbuild <FilePath+ModelProjectFileName>.modelproj /p:ValidateArchitecture=true

      - or -

      Browse to the folder that contains the modeling project (.modelproj) file and the layer diagram and then run MSBuild with the following custom property:

      msbuild /p:ValidateArchitecture=true 
    • To validate code against all modeling projects in the solution, run MSBuild with the following custom property:

      msbuild <FilePath+SolutionName>.sln /p:ValidateArchitecture=true 

      - or -

      Browse to the solution folder, which must contain a modeling project that contains a layer diagram, and then run MSBuild with the following custom property:

      msbuild /p:ValidateArchitecture=true

    Any errors that occur will be listed. For more information about MSBuild, see MSBuild and MSBuild Task.

For more information about validation errors, see Understand and resolve layer validation errors.

During the development process, you might want to suppress some of the reported conflicts during validation. For example, you might want to suppress errors that you are already addressing or that are not relevant to your particular scenario. When you suppress an error, it is a good practice to log a work item in Team Foundation.

To create a work item for a validation error

  • In the Error List window, right-click the error, point to Create Work Item, and then click the type of work item that you want to create.

Use these tasks to manage validation errors in the Error List window:


Follow these steps

Suppress selected errors during validation

Right-click the one or multiple selected errors, point to Manage Validation Errors, and then click Suppress Errors.

The suppressed errors appear with strikethrough formatting. When you run validation the next time, these errors will not appear.

Suppressed errors are tracked in a .suppressions file for the corresponding layer diagram file.

Stop suppressing selected errors

Right-click the selected suppressed error or errors, point to Manage Validation Errors, and then click Stop Suppressing Errors.

The selected suppressed errors will appear when you run validation the next time.

Restore all suppressed errors in the Error List window

Right-click anywhere in the Error List window, point to Manage Validation Errors, and then click Show All Suppressed Errors.

Hide all suppressed errors from the Error List window

Right-click anywhere in the Error List window, point to Manage Validation Errors, and then click Hide All Suppressed Errors.

You can perform layer validation every time that you run a local build. If your team uses Team Foundation Build, you can perform layer validation with gated check-ins, which you can specify by creating a custom MSBuild task, and use build reports to collect validation errors. To create gated check-in builds, see Define a Gated Check-In Build Process to Validate Changes.

To validate code automatically during a local build

  • Use a text editor to open the modeling project (.modelproj) file, and then include the following property:


- or -

  1. In Solution Explorer, right-click the modeling project that contains the layer diagram or diagrams, and then click Properties.

  2. In the Properties window, set the modeling project's Validate Architecture property to True.

    This includes the modeling project in the validation process.

  3. In Solution Explorer, click the layer diagram (.layerdiagram) file that you want to use for validation.

  4. In the Properties window, make sure that the diagram's Build Action property is set to Validate.

    This includes the layer diagram in the validation process.

To manage errors in the Error List window, see Manage Validation Errors.

To validate code automatically during a Team Foundation Build

  1. In Team Explorer, double-click the build definition, and then click Process.

  2. Under Build process parameters, expand Compilation, and type the following in the MSBuild Arguments parameter:


For more information about validation errors, see Understand and resolve layer validation errors. For more information about Team Foundation Build, see:

The following table describes layer validation issues and their resolution. These issues differ from errors that result from conflicts between the code and the design. For more information about these errors, see Understand and resolve layer validation errors.


Possible Cause


Validation errors do not occur as expected.

Validation does not work on layer diagrams that are copied from other layer diagrams in Solution Explorer and that are in the same modeling project. Layer diagrams that are copied in this way contain the same references as the original layer diagram.

  1. Add a new layer diagram to the modeling project.

  2. Copy the elements from the source layer diagram to the new diagram.

When you validate code against a layer diagram, validation errors occur when the code conflicts with the design. For example, the following conditions might cause validation errors to occur:

  • An artifact is assigned to the wrong layer. In this case, move the artifact.

  • An artifact, such as a class, uses another class in a way that conflicts with your architecture. In this case, refactor the code to remove the dependency.

To resolve these errors, update the code until no more errors appear during validation. You can perform this task in an iterative manner.

The following section describes the syntax that is used in these errors, explains the meaning of these errors, and suggests what you can do to resolve or manage them.




ArtifactN is an artifact that is associated with a layer on the layer diagram.

ArtifactTypeN is the type of ArtifactN, such as a Class or Method, for example:



The name of a namespace.


The name of a layer on the layer diagram.


The type of dependency relationship between Artifact1 and Artifact2. For example, Artifact1 has a Calls relationship with Artifact2.

Error Syntax

Error Description

AV0001: Invalid Dependency: Artifact1(ArtifactType1) --> Artifact2(ArtifactType2)

   Layers: LayerName1, LayerName2 | Dependencies: DependencyType

Artifact1 in LayerName1 should not have a dependency on Artifact2 in LayerName2 because LayerName1 does not have a direct dependency on LayerName2.

AV1001: Invalid Namespace: Artifact

   Layer: LayerName | Required Namespace: NamespaceName1 | Current Namespace: NamespaceName2

LayerName requires that its associated artifacts must belong to NamespaceName1. Artifact is in NamespaceName2, not NamespaceName1.

AV1002: Depends on Forbidden Namespace: Artifact1(ArtifactType1) | Artifact2(ArtifactType2)

   Layer: LayerName | Forbidden Namespace: NamespaceName | Dependencies: DependencyType

LayerName requires that its associated artifacts must not depend on NamespaceName. Artifact1 cannot depend on Artifact2 because Artifact2 is in NamespaceName.

AV1003: In Forbidden Namespace: Artifact(ArtifactType)

   Layer: LayerName | Forbidden Namespace: NamespaceName

LayerName requires that its associated artifacts cannot belong to NamespaceName. Artifact belongs to NamespaceName.

AV3001: Missing Link: Layer 'LayerName' links to 'Artifact' which cannot be found. Are you missing an assembly reference?

LayerName links to an artifact that cannot be found. For example, a link to a class might be missing because the modeling project is missing a reference to the assembly that contains the class.

AV9001: Architectural analysis found internal errors. Results might not be complete. For more information, see the detailed build event log or output window.

See the build event log or output window for more details.