[C++] Equality assertions don't handle Inf / -Inf properly

[asfimport]

I got this error when working on a PR which added unit tests:

../src/arrow/testing/gtest_util.cc:101: Failure
Failed
Expected:
  [
    2.5,
    inf,
    -inf
  ]
Actual:
  [
    2.5,
    inf,
    -inf
  ]

Reporter: Antoine Pitrou / @pitrou
Assignee: Liya Fan / @liyafan82

PRs and other links:

• GitHub Pull Request #7826

_{Note: This issue was originally created as ARROW-9495. Please see the migration documentation for further details.}

[asfimport]

Liya Fan / @liyafan82:
@pitrou Thank you for opening this issue.
The reason may be that our test cases compare arrays by Array::ApproxEquals to workarond floating point errors, however, Array::ApproxEquals is not working for infinity/-infinity.

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 7826
#7826