Content-modification system with testing and reporting feature

A non-transitory computer-readable storage medium, having stored thereon program instructions that, upon execution by at least one processor, cause performance of a first set of operations comprising:

• identifying, by a content-presentation device, an upcoming content modification opportunity on an identified channel, wherein the upcoming content modification opportunity relates to a modifiable content-segment;
• receiving, by the content-presentation device, the modifiable content-segment;
• performing, by the content-presentation device, a second set of operations to prepare the content-presentation device to perform a content-modification operation in connection with the upcoming content modification opportunity on the identified channel;
• receiving, by the content-presentation device, an instruction to operate in a test mode;
• and
• responsive to receiving the instruction, outputting, by the content-presentation device, for presentation the modifiable content-segment without a modification that relates to supplemental content.

A computing system comprising:

• at least one processor;
• and
• a non-transitory computer-readable storage medium, having stored thereon program instructions that, upon execution by the at least one processor, cause performance of a first set of operations comprising:
• identifying, by a content-presentation device, an upcoming content modification opportunity on an identified channel, wherein the upcoming content modification opportunity relates to a modifiable content-segment;
• receiving, by the content-presentation device, the modifiable content-segment;
• performing, by the content-presentation device, a second set of operations to prepare the content-presentation device to perform a content-modification operation in connection with the upcoming content modification opportunity on the identified channel;
• receiving, by the content-presentation device, an instruction to operate in a test mode;
• responsive to receiving the instruction, outputting, by the content-presentation device, for presentation the modifiable content-segment without a modification that relates to supplemental content;
• and
• transmitting reporting data that indicates that a time the content-presentation device retrieved the supplemental content is before a scheduled modification start-time of the content-modification operation.