$ cargo test -- --show-output
   Compiling silly-function v0.1.0 (file:///projects/silly-function)
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.60s
     Running unittests src/lib.rs (target/debug/deps/silly_function-160869f38cff9166)

running 2 tests
test tests::this_test_will_fail ... FAILED
test tests::this_test_will_pass ... ok

successes:

---- tests::this_test_will_pass stdout ----
I got the value 4


successes:
    tests::this_test_will_pass

failures:

---- tests::this_test_will_fail stdout ----
I got the value 8
thread 'tests::this_test_will_fail' panicked at src/lib.rs:19:9:
assertion `left == right` failed
  left: 10
 right: 5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    tests::this_test_will_fail

test result: FAILED. 1 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

error: test failed, to rerun pass `--lib`