libcnb-test: Stop exposing raw output in LogOutput (#607)

Since:
- There are no common use-cases that require raw output, and buildpacks
  in the wild aren't using these fields (checked using GitHub code search).
- It saves beginners from having to think about which `LogOutput`
  field they should be using.

This cleanup has been split out of the future Bollard migration PR.

CHANGELOG.md

@@ -12,7 +12,9 @@ separate changelogs for each crate were used. If you need to refer to these old
 
 ### Changed
 
-- `libcnb-test`: `ContainerContext::address_for_port` now returns `SocketAddr` directly instead of `Option<SocketAddr>`. ([#605](https://github.com/heroku/libcnb.rs/pull/605))
+- `libcnb-test`:
+  - `ContainerContext::address_for_port` now returns `SocketAddr` directly instead of `Option<SocketAddr>`. ([#605](https://github.com/heroku/libcnb.rs/pull/605))
+  - `LogOutput` no longer exposes `stdout_raw` and `stderr_raw`. ([#607](https://github.com/heroku/libcnb.rs/pull/607))
 - `libcnb-package`: buildpack target directory now contains the target triple. Users that implicitly rely on the output directory need to adapt. The output of `cargo libcnb package` will refer to the new locations. ([#580](https://github.com/heroku/libcnb.rs/pull/580))
 - `libherokubuildpack`: Switch the `flate2` decompression backend from `miniz_oxide` to `zlib`. ([#593](https://github.com/heroku/libcnb.rs/pull/593))
 - Bump minimum external dependency versions. ([#587](https://github.com/heroku/libcnb.rs/pull/587))

libcnb-test/src/log.rs

@@ -3,8 +3,6 @@ use tokio_stream::{Stream, StreamExt};
 /// Container log output.
 #[derive(Debug, Default)]
 pub struct LogOutput {
-    pub stdout_raw: Vec<u8>,
-    pub stderr_raw: Vec<u8>,
     pub stdout: String,
     pub stderr: String,
 }
@@ -19,25 +17,26 @@ pub(crate) async fn consume_container_log_output<
         .collect::<Result<Vec<bollard::container::LogOutput>, E>>()
         .await
         .map(|log_output_chunks| {
-            let mut acc = LogOutput::default();
+            let mut stdout_raw = Vec::new();
+            let mut stderr_raw = Vec::new();
 
             for log_output_chunk in log_output_chunks {
                 match log_output_chunk {
                     bollard::container::LogOutput::StdOut { message } => {
-                        acc.stdout_raw.append(&mut message.to_vec());
+                        stdout_raw.append(&mut message.to_vec());
                     }
                     bollard::container::LogOutput::StdErr { message } => {
-                        acc.stderr_raw.append(&mut message.to_vec());
+                        stderr_raw.append(&mut message.to_vec());
                     }
                     unimplemented_message => {
                         unimplemented!("message unimplemented: {unimplemented_message}")
                     }
                 }
             }
 
-            acc.stdout = String::from_utf8_lossy(&acc.stdout_raw).to_string();
-            acc.stderr = String::from_utf8_lossy(&acc.stderr_raw).to_string();
-
-            acc
+            LogOutput {
+                stdout: String::from_utf8_lossy(&stdout_raw).to_string(),
+                stderr: String::from_utf8_lossy(&stderr_raw).to_string(),
+            }
         })
 }