dotCover 2019.2 Help

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JetBrains dotCover is a .NET unit test runner and code coverage tool. dotCover lets us analyze how much of our .NET application code is actually being tested. By measuring method calls during unit tests or when running the application manually, dotCover shows us which statements were covered and which were not.

dotCover integrates into Visual Studio 2010, 2012, 2013, 2015, 2017, and 2019. After installing dotCover with or without any other ReSharper Ultimate tools and opening Visual Studio, you will find dotCover commands under the ReSharper | Unit Tests and ReSharper | Cover in the main menu. From these menus, you can execute various commands available in dotCover.

Unit testing and code coverage

The most basic scenario of using dotCover is measuring how much of your code do tests cover. Baseline conditions are as follows. You have a solution opened in Visual Studio. Code in the solution is covered with some unit tests. The task is to understand how much of the code is covered.

To analyze coverage of unit tests in a solution

  1. Choose ReSharper | Unit Tests | Unit Tests from the main menu. This will open the Unit Test Explorer tool window. Here you can take a look at how many tests are there in the solution.

    unit test explorer howto

  2. In the Unit Test Explorer window, select the tests whose coverage you want to analyze. If you want to analyze all tests, select the top-level node in the tree. Note that you can limit coverage scope by using coverage filters.

  3. Click Cover Unit Tests ThemedIcon Cover Screen Gray . This will run a normal unit tests session but dotCover will collect coverage data in the background. Test results will be shown in real time in the newly opened Unit Test Sessions window. Coverage results (how tests cover particular classes and methods in your code) will be shown in the Unit Test Coverage tool window.

    unit test sessions coverage

  4. If you want to see what tests exactly cover a particular class or method, select it in the Unit Test Coverage window and in the context menu choose Show Covering Tests.

    covering tests

  5. Visualize code coverage by clicking the ThemedIcon Highlighting Screen Gray Highlight code button.

    default coverage highlighting
    By default, coverage and test results are shown by markers in the left gutter of the Visual Studio editor: a marker is red if any tests related to the current statement are failing, green if all tests are passing, and grey if there are no tests covering this statement.

  6. The Unit Test Coverage window contains one more very useful metric. After you click dotCover hot spots icon Hot Spots, it will show you a "cloud" of potentially risky classes: the classes that have high cyclomatic complexity but are poorly covered with tests.

    hot spots coverage

Coverage of applications

dotCover enables us to calculate code coverage for a specific use-case scenario. Hitting Ctrl+Alt+K P or choosing ReSharper | Cover | Cover Startup Project in the menu launches our solution's startup project under dotCover control. Alternatively, Ctrl+Alt+K K or ReSharper | Cover | Cover Application... enables us to specify the application to calculate code coverage for.

dotCover Dialog Boxes Coverage Configuration

Next, we can run our application and work through a use-case scenario and tell dotCover to get a snapshot once completed. As long as the tested application runs under dotCover control, the controller dialog is displayed where you can click Get Snapshot and inspect which lines of code were covered when we worked with the tested application.

dotCover controller

Filtering coverage results

Code coverage results can be cluttered with infrastructure code or projects that we are not interested in inspecting. We can exclude specific nodes by right-clicking them and choosing Exclude and Create Coverage Filter:

Excluding nodes from dotCover coverage results

Excluding item and creating a corresponding runtime coverage filter will tell dotCover not to cover the item next time we run coverage analysis.

Coverage filters can also be managed through the Coverage Filters dialog (Ctrl+Alt+K F, or ReSharper | Cover | Edit Coverage Filters... ). Filters can be defined for any solution you open or scoped to the active solution.

dotCover helps filtering coverage results

Once you've mastered these basics, you can learn the keyboard shortcuts or check how to work with the command-line version of dotCover.

Last modified: 30 September 2019