The Scenario Definition section contains all files needed by your test. It also controls which test executor to use (JMeter, Gatling, Selenium, etc...) and which file to begin the test with.
Uploading or Including Files
Click the '+' icon to begin uploading files or click "Shared Folder" to include files from Shared Folders:
Once you have one or more files uploaded or included, you'll see the full Scenario Definition module. To add additional files, or to add/remove shared folders, hover over the "+" on the right and make your selection:
NOTE: You may on occasion find a file you upload to be marked invalid, possibly with a missing scenario message. This isn't always a show-stopper; if your main test file is marked invalid, there may be a problem, so double-check your script and try re-uploading it. If a test file other than your main file (such as additional JMX test fragments, for example), is marked invalid, you may safely ignore the warning. "Invalid" only means there may possibly be a problem if you were to designate that file as your main test script.
For more information about uploading files and including files from Shared Folders, have a look at "Uploading Files and Shared Folders".
Auto-Detect of Test Type and Entry Script
The first file with an extension that matches a supported test type will be selected as the primary or "entry" script to start your test with. BlazeMeter will use that file's type to set the Test type (JMeter for a JMX file, Gatling for a Scala file, etc.).
Manually choosing script to start test with
If you upload more than one script file, the additional script files will have an open circle next to them:
To select a different script as the one to start your test with, just click the open circle icon and it will change to an arrow icon, updating the "Start test with" field for you.
Manually choosing Test type if needed
Because some testing tools use the same type of files, you may need to set the Test type manually. If so, just use the drop-down to set test type and be sure the right file is marked to start the test with.
Distributing CSV data to engines: Split CSV
If your test will run on multiple engines, you might not want two engines to use the same row of data (for instance, to execute a login step for the same user).
To split your CSV into unique files for each server, select the 'Split CSV files with a unique subset per engine' option. The rows of data will be distributed to the engines as follows: line one will go to engine one, line two to engine two, line three to engine one, etc.
For more information about using a CSV file in your test, please refer to this article "CSV file Upload".