Unnecessary project rebuilds when unit testing in Visual Studio

Question

I know about this question (and answers), but despite trying all the suggested options I am still stuck.

I have a solution with multiple projects, but for this particular case let's say I've got my ExampleProjectA and a corresponding unit test project ExampleProjectATest. The first one is added as a reference to the test project - not via Visual Studio's "Project References" but as a link to the DLL (something like "..\Path\$(Config)\ExampleProjectA.dll") - this is due to build server requirements in our company, but the problem also existed when we still had "Project References".

• Building and then running a single unit test works fine
• Changing just a single letter in a unit test and then letting the test run always results in a rebuild of ExampleProjectA, even though this shouldn't be necessary
• Setting all (there were only a few) files in ExampleProjectA from "Copy always" to "Copy if newer" in their respective properties didn't help
• Checking the checkbox under Tools => Options => Projects and Solutions => Build an Run (see below) also didn't change anything

To see if there was any more information available, I changed the build output settings to diagnostic. Each time a rebuild of ExampleProjectA is triggered, the first line in the output windows is

1>Project 'ExampleProjectATest' is not up to date. Input file 'c:\tfs\mysolution-dev\exampleprojectatest\myfolder\namegeneratortest.cs' is modified after output file 'C:\tfs\mysolution-dev\exampleprojectatest\bin\Release\exampleprojectatest.pdb'.

The class name written to the window (e.g. namegeneratortest.cs) changes according to which test file I change.

Not sure why this message comes up, but the next step was to disable the debugging information as shown below under Project properties => Build => Advanced => Output => Debug Info => None:

Still the same, nothing's changed.

Another thing I tried was to check the timestamps of the files contained in my solution folder (as there was a case where a user had a file with a future timestamp - see linked post) - to no avail.

Last thing I tried was to change the build settings in the Configuration Manager to a different target platform - some settings wouldn't let me build the solution successfully, some other settings did, but the problem described persisted, so no change.

The behaviour is similar (not the same though) with both the Visual Studio Test Runner and the one provided by ReSharper.

Visual Studio Test Runner

Project 'ExampleProject' is not up to date. Input file 'C:\tfs\mysolution-dev\exampleprojecta\Views\Shared\someview.cshtml' is modified after output file 'C:\tfs\mysolution-dev\exampleprojecta\bin\exampleprojecta.pdb'.

ReSharper Test Runner

Project 'ExampleProjectATest' is not up to date. Input file 'c:\tfs\mysolution-dev\exampleprojectatest\myfolder\namegeneratortest.cs' is modified after output file 'C:\tfs\mysolution-dev\exampleprojectatest\bin\Release\exampleprojectatest.pdb'.

I'm using Visual Studio 2013 Premium Edition with ReSharper 8.2 and the latest updates, the projects in our solution file are in C#.

Update

To clarify - the first line in the output window does show that the test project has to be rebuilt - this is fine. The following lines, however, indicate that also ExampleProjectA has to be rebuilt, which shouldn't be necessary. Subsequent messages to the output window also show that other projects (referenced from ExampleProjectA have to be rebuilt.

Update 2

Despite installing Update 4, nothing has changed.

Answer 1

For my case the solution was to change the build action of a config file from "Copy always" to "Copy if newer". It took a while to find as I had to change the build output details to get the details about which file was causing the error, e.g.

Project 'xyz' is not up to date. Project item 'c:\my\path\web.config.dev' has 'Copy to Output Directory' attribute set to 'Copy always'.

From my experience it can also happen that different file names are shown when building multiple times, so make sure you have the right one and / or build again if the problem persists.

Also have a look at this question and its answers to find some more information.

Answer 2

I have worked around this problem by deleting the .pdb file in the \obj folder. It seems that visual studio is checking file modification time to decide if it should build or not the project (in your case ExampleProjectA) and the .cshtml is newer than the pdb. But when launching the build, project changes in .cshtml files are not triggering the .pdb rebuild, so the problem remains.

By deleting the .pdb in \obj folder (not in \bin as the file there is copied from \obj and would keep the old modification time) the modification time for the .pdb is newer than the .cshtml and the VS doesn't need to build the project before running the tests. Of course this only works until the next time you modify a .cshtml file, that's why I qualify it as just a workaround.