The <Execution> element defines how your tests are executed. The following attributes are available:

Attribute Required/Optional Description
stopAfterFailures Optional The number of failed tests after which the execution of all tests is stopped. Set this to 0 (zero) to execute all tests, irrespective of the number of failures. If not specified, this defaults to 10.
Note: The value in the default .srprofile shipped with the NuGet package is 3.
testSchedulingMode Optional Determines the order in which SpecRun executes your tests:
Sequential: Tests are always executed in the same order (default). The order in which tests are executed is predictable and always the same, but cannot be influenced manually.
Random: The order of tests is randomised. This can be useful to detect flickering scenarios that may pass/fail depending on the order in which the other tests area executed.
Adaptive: SpecRun uses the statistics available in the pass/fail history to determine which tests to run first. Previously failing tests and new tests are executed before successful and stable tests.
Note: If you set the testSchedulingMode to Adaptive when no previous test execution results are available (e.g. no server has been configured, or the server is unreachable), the tests are executed using the Random option instead.
testThreadCount Optional The number of tests threads used to execute tests (default=1).
While there is no maximum number of threads, setting this value too high can reduce performance as the individual threads compete for processing power. Setting the number of threads to one less that your number of cores is recommended for Process test thread isolation (testThreadIsolation setting). You can generally use higher numbers for isolation using AppDomain and SharedAppDomains.
Note: Just increasing the number of threads on its own may cause issues, e.g. if the threads access the same database. It thus makes sense to combine this with a relocation and transformation of the .config file using the {TestThreadId} placeholder in the name of the new file and database instances (see below).
Note: Before and After hooks (e.g. BeforeTestRun, AfterTestRun etc.) are executed per thread.
retryFor Optional Determines which tests should be retried based on their status. Available options:
None: No tests are retried
Failing: Failing test are retried (default)
All: All tests are retried, including those that pass
Note: Tests are retried immediately after returning the corresponding status and before any subsequent tests are executed.
retryCount Optional The number of times tests whose execution status matches the value defined in <retryFor> are retried (default = 2).
apartmentState Optional Sets the apartment state used to execute the tests. Possible values:
STA: Single Threaded Apartment. Use this if your application is not thread-safe
MTA: Multi-Threaded Apartment
Unknown: The ApartmentState is not set (default); tests run in same thread as SpecFlow+