Find method to clarify gtest output statements.

Generally, we can perform the tests then the test will give an output on how the test failed. But, this isn't immediately clear to the students sometimes. We have been getting by doing
```
ASSERT_EQ(output, expected) <

Start by reviewing the existing ASSERT_EQ usage and the ASSERT_STD_OUTPUT_MSG macro shown in the issue, including how it captures standard output. Determine how test failures should communicate where and how students went wrong, then verify that the resulting gtest output is clearer for failed standard-output checks.

Written by the indexing model from the issue text.