Merge #14935: tests: Test for expected return values when calling functions returning a success code

c84c2b8c92 tests: Test for expected return values when calling functions returning a success code (practicalswift)

Pull request description:

  Test for expected return values when calling functions returning a success code (instead of discarding the return values).

  **Note to reviewers:** The following commands can be used to verify that the only text fragments added in this PR are `BOOST_CHECK(`, `!` and `)` :

  ```
  $ git diff HEAD~1 | grep -E '^[\-][^\-]' | cut -b2- > before.txt
  $ git diff HEAD~1 | grep -E '^[\+][^\+]' | cut -b2- > after.txt
  $ cat after.txt | sed 's/BOOST_CHECK(//g' | sed 's/));/);/g' | tr -d '!' > after-sed.txt
  $ diff -u before.txt after-sed.txt
  $
  ```

Tree-SHA512: ff0863ef2046a2eda3c44e9c6b9aedfe167881f2fa58db29fef859416831233ef6502a3a11fd2322bc1a924db83df8d4a5c5879298007f2a7b085e2a7286af70

src/test/cuckoocache_tests.cpp

@@ -141,7 +141,7 @@ static void test_cache_erase(size_t megabytes)
         set.insert(hashes_insert_copy[i]);
     /** Erase the first quarter */
     for (uint32_t i = 0; i < (n_insert / 4); ++i)
-        set.contains(hashes[i], true);
+        BOOST_CHECK(set.contains(hashes[i], true));
     /** Insert the second half */
     for (uint32_t i = (n_insert / 2); i < n_insert; ++i)
         set.insert(hashes_insert_copy[i]);
@@ -221,7 +221,7 @@ static void test_cache_erase_parallel(size_t megabytes)
             size_t start = ntodo*x;
             size_t end = ntodo*(x+1);
             for (uint32_t i = start; i < end; ++i)
-                set.contains(hashes[i], true);
+                BOOST_CHECK(set.contains(hashes[i], true));
         });
 
     /** Wait for all threads to finish