CTA Sequence Development & Customization 2 — Questions and Answers
Question 1: Which TestStand feature allows you to define a custom execution flow by overriding the default behavior of the Sequential process model?
- Station Callback sequences (Correct answer)
- Thread locals
- Sequence file properties
- Step type plugins
Correct answer: Station Callback sequences
Station Callback sequences let you override default process model behavior at specific execution hooks without modifying the process model itself.
Question 2: In TestStand, what is the primary purpose of the 'Cleanup' subsequence within a sequence?
- To initialize variables before the main body runs
- To execute steps that must run regardless of pass/fail outcome (Correct answer)
- To define the sequence's public interface
- To reset the UUT between test runs
Correct answer: To execute steps that must run regardless of pass/fail outcome
The Cleanup subsequence always executes after the Main Body and Post-Expression, ensuring resources are released even if an error occurred.
Question 3: When using a Template sequence in TestStand, what is the key advantage over copying an existing sequence?
- Templates execute faster at runtime
- Templates allow dynamic step type loading
- Changes to the template automatically propagate to all sequences based on it (Correct answer)
- Templates bypass sequence file locking
Correct answer: Changes to the template automatically propagate to all sequences based on it
Template sequences enable inheritance so that modifications to the base template are reflected in all derived sequences, reducing maintenance overhead.
Question 4: A developer wants to pass a large data array between two separate sequence files without using global variables. What is the recommended approach?
- Use FileGlobals in both sequence files
- Pass the array as a parameter in the subsequence call step (Correct answer)
- Store the array in a station global
- Use the TestStand API to write to shared memory
Correct answer: Pass the array as a parameter in the subsequence call step
Passing data as parameters in subsequence call steps keeps data encapsulated and avoids the side effects of shared globals.
Question 5: Which locals scope in TestStand is accessible only within the currently executing sequence and is destroyed when the sequence exits?
- FileGlobals
- StationGlobals
- Locals (Correct answer)
- RunState.Root
Correct answer: Locals
Locals are sequence-scoped variables that exist only for the lifetime of that sequence's execution.
Question 6: What happens when a TestStand step's 'Run Mode' is set to 'Skip'?
- The step executes but its result is ignored
- The step is not executed and its status is set to Skipped (Correct answer)
- The step pauses execution for user input
- The step executes in a separate thread
Correct answer: The step is not executed and its status is set to Skipped
Setting Run Mode to Skip causes TestStand to bypass that step entirely, recording it with a Skipped status in the report.
Question 7: In a TestStand sequence, which expression context is evaluated AFTER the step's code module executes?
- Pre-Expression
- Post-Expression (Correct answer)
- Step Properties expression
- Sequence Pre-Step
Correct answer: Post-Expression
The Post-Expression is evaluated after the code module runs, commonly used to check results or set flags based on step output.
CTA Sequence Development & Customization 2
Which TestStand feature allows you to define a custom execution flow by overriding the default behavior of the Sequential process model?