tests: spawn_test: use BOOST_CHECK_EQUAL() for checking equality of t…

…emporary_buffer

so we can have better understanding of failures, if this test fails.

Signed-off-by: Kefu Chai <[email protected]>

Closes scylladb#1327

tests/unit/spawn_test.cc

@@ -100,7 +100,7 @@ SEASTAR_TEST_CASE(test_spawn_input) {
             }).then([&stdout] {
                 return stdout.read_exactly(text.size());
             }).then([] (temporary_buffer<char> echo) {
-                BOOST_CHECK(echo == echo.copy_of(text));
+                BOOST_CHECK_EQUAL(sstring(echo.get(), echo.size()), text);
             }).finally([&p] {
                 return p.wait().discard_result();
             });