tests: hide simulator output by default, indent when showing

The test output was almost impossible to read with all the simulator
output being dumped alongside the test output.

Now this is hidden. With `--nocapture` it is shown indented below each
test.

Author: benma

README-rust.md

@@ -20,6 +20,10 @@ To run them, use:
 
     cargo test --features=simulator,tokio -- --test-threads 1
 
+Use `--nocapture` to also see some useful simulator output.
+
+    cargo test --features=simulator,tokio -- --test-threads 1 --nocapture
+
 If you want to test against a custom simulator build (e.g. when developing new firmware features),
 you can run:
 

tests/util/mod.rs

@@ -6,6 +6,7 @@
 use bitcoin::hashes::Hash;
 use reqwest::Client;
 use serde::{Deserialize, Serialize};
+use std::io::BufRead;
 use std::os::unix::fs::PermissionsExt;
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command};
@@ -37,11 +38,33 @@ struct Server(Child);
 
 impl Server {
     fn launch(filename: &str) -> Self {
-        Self(
-            Command::new(filename)
-                .spawn()
-                .expect("failed to start server"),
-        )
+        //let mut command = Command::new(filename);
+
+        let mut command = Command::new("stdbuf");
+        command
+            .arg("-oL") // Line buffering for stdout
+            .arg(filename)
+            .stdout(std::process::Stdio::piped());
+
+        command.stdout(std::process::Stdio::piped()); // Capture stdout
+
+        let mut child = command.spawn().expect("failed to start server");
+
+        // Take stdout handle from child
+        let stdout = child.stdout.take().unwrap();
+
+        // Spawn a thread to process the output, so we can print it indented for clarity.
+        std::thread::spawn(move || {
+            let reader = std::io::BufReader::new(stdout);
+            for line in reader.lines() {
+                match line {
+                    Ok(line) => println!("\t\t{}", line),
+                    Err(e) => eprintln!("Error reading line: {}", e),
+                }
+            }
+        });
+
+        Self(child)
     }
 }
 
@@ -127,7 +150,8 @@ pub async fn test_simulators_after_pairing(
         download_simulators().await.unwrap()
     };
     for simulator_filename in simulator_filenames {
-        println!("Simulator tests using {}", simulator_filename);
+        println!();
+        println!("\tSimulator tests using {}", simulator_filename);
         let _server = Server::launch(&simulator_filename);
         let noise_config = Box::new(bitbox_api::NoiseConfigNoCache {});
         let bitbox = bitbox_api::BitBox::<bitbox_api::runtime::TokioRuntime>::from_simulator(