Which of the following would NOT prompt a test of a spring switch?

The correct answer indicates that a cautious signal shown by the switch indicator would not necessitate a test of a spring switch. A caution signal typically alerts crew members to be vigilant but does not imply that the switch mechanism itself requires immediate evaluation or testing.

In railway operations, the switch indicator's role is to communicate the current position of the switch to the crew, and a caution signal may indicate an issue further down the line or an upcoming operational concern rather than a direct malfunction of the switch itself.

Other options, such as the switch being lined for the diverging route or being spiked, would suggest conditions that could require examining the switch's functionality to ensure safe operations, as they may create scenarios where switch integrity is critical. Additionally, scheduled training exercises often involve practical tests of equipment functionality, including spring switches, to maintain safety readiness.