Adding users dynamically is valuable in Multi-Test runs which assess the target server limits. While running a load test, you might notice that the target servers are handling the load quite well. As an alternative to shutting down and starting a new test with a different configuration, you can simply add additional tests to your active Multi-Test on the fly, adding more users or load. Once a test is added to the Multi-Test, its results will be aggregated with the rest of the Multi-Test results, forming a big picture analysis.

You can add any test while the Multi-Test is running by simply starting the single test, then selecting the option to add it to the Multi-Test.

Note: Only tests within the same project can be included in a Multi-Test. 

• Add Tests Dynamically
• Add Tests via the API

Add Tests Dynamically

Follow these steps:

1. Create a Multi-Test and run it.
   
2. If you believe you could use some more load, or want to add another scenario to the Multi-Test, select and run your single test as usual. Click Tests, Show all tests.
   A list of all available tests appears on the left side panel. 
3. Click the 'Play' button for the test you want to add.
   
   
4. In the pop-up window, expand the Run this test as part of a master session? drop-down list.
5. Select to run as a single standalone test, or as part of any Multi-Test that is currently active.

If you choose to run the test under the Multi-Test, then right after the new test finishes its startup stage, its results will be aggregated together with the overall results of the Multi-Test.
In the report shown below, notice the moment in which a new test was added to the load.

Add Tests via the API

Alternatively, you can add a single test to a currently running multi-test via the API. To do so, perform a POST to the following endpoint:

https://a.blazemeter.com/api/v4/tests/{{testId}}/start?delayedStart=true&masterId={{masterId}}

The above API includes the following options:

• {{testID}} = The test ID of the single test you wish to add.
• {{masterID}} = The master ID of the multi-test you wish to add the single test to.

For more information, see the API documentation.