# How To Use Test Runner

The **Test Runner** brings *nUnit* style functionality to Linx, making regression testing of a Linx solution easier.

The Test Runner [console](/testrunner/testrunnerconsole.md) can also be used to run these tests.

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## Test Project

The test runner will execute tests created in a Test Project. To add a Test Project, right-click on the Solution and select “Add Test Project.”

<figure><img src="/files/miabHruMaCCLUc2BuBaX" alt="Test Project Add"><figcaption></figcaption></figure>

Tests are added to a Test Project by adding functions and setting their type. Functions added to a Test Project have the following types:

* Function – a standard Linx function ignored by the test runner
* One-time setup – runs once before tests run
* One-time teardown – runs once after tests finish
* Setup – runs before every test
* Teardown – runs after every test
* Test – a test

<figure><img src="/files/Yl6HNB0oapds9R0lNjF6" alt="Type of Tests"><figcaption></figcaption></figure>

Test, setup, teardown, one-time setup, and one-time teardown functions can be added anywhere in a Test Project. The Test Runner executes test functions in the following order:

1. Execute one-time setup functions in parent folders starting from the project root and working down.
2. For each folder:
   1. Execute one-time setup functions
   2. For each test function:
      * Execute setup functions
      * Execute the test function
      * Execute teardown functions
      * For each sub-folder, repeat 2
   3. Execute one-time teardown functions
3. Execute one-time teardown functions in parent folders, starting with the parent and working up.

Multiple setup or one-time setup functions in the same folder execute alphabetically.

Multiple teardown or one-time teardown functions in the same folder execute in reverse alphabetical order.

If any setup or one-time setup function fails, the test run for the folder stops.

Multiple tests in the same folder may run in any order.

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## Executing tests

To run tests, right-click on any test function or folder that contains tests and select "Run Tests". If you select a folder or the Test Project, all the tests it contains, including those in subfolders, will run.

<figure><img src="/files/Iyidnmc7SzenuXshWEJt" alt="Run Tests"><figcaption></figcaption></figure>

See the results of tests in the Test Explorer. Here you can also see the error if a test failed.

<figure><img src="/files/UbvzEOeIhkTURlwVINCS" alt="Test Explorer With Error"><figcaption></figcaption></figure>

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## Start and Stop a Service

Use the [StartService](/reference/plugins/linx/content/startservice.md) and [StopService](/reference/plugins/linx/content/stopservice.md) functions to start or stop a Linx service. Services are typically started in setup functions and stopped in teardown functions.

## Setup and Teardown Data

Setup and teardown functions can pass data to downstream setup, teardown, or test functions. To emit data, add a result to the emitting function. To consume the value, add a parameter with the same name and type to the consuming function.


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