run exercises with CWD set to their directory

exercises/24_async/async1.rs

@@ -6,18 +6,14 @@
 // Let's simulate this using asynchronous programming. Each person is
 // represented as an asynchronous task, which can be executed concurrently.
 
-const SCORES_CLASS_A: &str = "exercises/24_async/scores_class_a.txt";
-const SCORES_CLASS_B: &str = "exercises/24_async/scores_class_b.txt";
-const SCORES_CLASS_C: &str = "exercises/24_async/scores_class_c.txt";
-
 // Async tasks need to be executed by a "runtime", which is not provided by
 // Rust's standard library. Here, we use the mainstream runtime `tokio`.
 // The macro `tokio::main` wraps the entire main function in a runtime.
 #[tokio::main]
 async fn main() {
-    let mean_score_a = tokio::spawn(calculate_mean_score(SCORES_CLASS_A));
-    let mean_score_b = tokio::spawn(calculate_mean_score(SCORES_CLASS_B));
-    let mean_score_c = tokio::spawn(calculate_mean_score(SCORES_CLASS_C));
+    let mean_score_a = tokio::spawn(calculate_mean_score("scores_class_a.txt"));
+    let mean_score_b = tokio::spawn(calculate_mean_score("scores_class_b.txt"));
+    let mean_score_c = tokio::spawn(calculate_mean_score("scores_class_c.txt"));
 
     // TODO: Await the spawned tasks to check their results.
     assert_eq!(mean_score_a, 84); // alice

solutions/24_async/async1.rs

@@ -6,18 +6,14 @@
 // Let's simulate this using asynchronous programming. Each person is
 // represented as an asynchronous task, which can be executed concurrently.
 
-const SCORES_CLASS_A: &str = "exercises/24_async/scores_class_a.txt";
-const SCORES_CLASS_B: &str = "exercises/24_async/scores_class_b.txt";
-const SCORES_CLASS_C: &str = "exercises/24_async/scores_class_c.txt";
-
 // Async tasks need to be executed by a "runtime", which is not provided by
 // Rust's standard library. Here, we use the mainstream runtime `tokio`.
 // The macro `tokio::main` wraps the entire main function in a runtime.
 #[tokio::main]
 async fn main() {
-    let mean_score_a = tokio::spawn(calculate_mean_score(SCORES_CLASS_A));
-    let mean_score_b = tokio::spawn(calculate_mean_score(SCORES_CLASS_B));
-    let mean_score_c = tokio::spawn(calculate_mean_score(SCORES_CLASS_C));
+    let mean_score_a = tokio::spawn(calculate_mean_score("scores_class_a.txt"));
+    let mean_score_b = tokio::spawn(calculate_mean_score("scores_class_b.txt"));
+    let mean_score_c = tokio::spawn(calculate_mean_score("scores_class_c.txt"));
 
     assert_eq!(mean_score_a.await.unwrap(), 84); // alice
     assert_eq!(mean_score_b.await.unwrap(), 89); // bob

src/cmd.rs

@@ -13,7 +13,12 @@ const TIMEOUT_SECS: u64 = 30;
 
 /// Run a command with a description for a possible error and append the merged stdout and stderr.
 /// The boolean in the returned `Result` is true if the command's exit status is success.
-fn run_cmd(mut cmd: Command, description: &str, output: Option<&mut Vec<u8>>) -> Result<bool> {
+fn run_cmd(
+    mut cmd: Command,
+    description: &str,
+    cwd: Option<&str>,
+    output: Option<&mut Vec<u8>>,
+) -> Result<bool> {
     let spawn = |mut cmd: Command| {
         // The closure drops `cmd` which prevents a pipe deadlock.
         cmd.stdin(Stdio::null())
@@ -25,6 +30,9 @@ fn run_cmd(mut cmd: Command, description: &str, output: Option<&mut Vec<u8>>) ->
             .wait_timeout(Duration::from_secs(TIMEOUT_SECS))
             .with_context(|| format!("Failed to wait on `{description}` to exit"))
     };
+    if let Some(cwd) = cwd {
+        cmd.current_dir(cwd);
+    }
 
     let mut handle = if let Some(output) = output {
         let (mut reader, writer) =
@@ -133,7 +141,12 @@ impl CmdRunner {
     }
 
     /// The boolean in the returned `Result` is true if the command's exit status is success.
-    pub fn run_debug_bin(&self, bin_name: &str, output: Option<&mut Vec<u8>>) -> Result<bool> {
+    pub fn run_debug_bin(
+        &self,
+        bin_name: &str,
+        cwd: &str,
+        output: Option<&mut Vec<u8>>,
+    ) -> Result<bool> {
         // 7 = "/debug/".len()
         let mut bin_path =
             PathBuf::with_capacity(self.target_dir.as_os_str().len() + 7 + bin_name.len());
@@ -141,7 +154,7 @@ impl CmdRunner {
         bin_path.push("debug");
         bin_path.push(bin_name);
 
-        run_cmd(Command::new(&bin_path), bin_name, output)
+        run_cmd(Command::new(&bin_path), bin_name, Some(cwd), output)
     }
 }
 
@@ -161,7 +174,7 @@ impl CargoSubcommand<'_> {
 
     /// The boolean in the returned `Result` is true if the command's exit status is success.
     pub fn run(self, description: &str) -> Result<bool> {
-        run_cmd(self.cmd, description, self.output)
+        run_cmd(self.cmd, description, None, self.output)
     }
 }
 
@@ -179,7 +192,7 @@ mod tests {
         cmd.arg("Hello");
 
         let mut output = Vec::with_capacity(8);
-        run_cmd(cmd, "echo …", Some(&mut output)).unwrap();
+        run_cmd(cmd, "echo …", None, Some(&mut output)).unwrap();
 
         assert_eq!(output, b"Hello\n\n");
     }

src/exercise.rs

@@ -36,6 +36,7 @@ pub fn solution_link_line(
 // Compilation must be done before calling this method.
 fn run_bin(
     bin_name: &str,
+    cwd: &str,
     mut output: Option<&mut Vec<u8>>,
     cmd_runner: &CmdRunner,
 ) -> Result<bool> {
@@ -46,7 +47,7 @@ fn run_bin(
         output.push(b'\n');
     }
 
-    let success = cmd_runner.run_debug_bin(bin_name, output.as_deref_mut())?;
+    let success = cmd_runner.run_debug_bin(bin_name, cwd, output.as_deref_mut())?;
 
     if let Some(output) = output
         && !success
@@ -123,6 +124,14 @@ pub trait RunnableExercise {
             output.clear();
         }
 
+        let cwd_buf;
+        let cwd = if let Some(dir) = self.dir() {
+            cwd_buf = format!("exercises/{dir}");
+            cwd_buf.as_str()
+        } else {
+            "exercises"
+        };
+
         if self.test() {
             let output_is_some = output.is_some();
             let mut test_cmd = cmd_runner.cargo("test", bin_name, output.as_deref_mut());
@@ -131,7 +140,7 @@ pub trait RunnableExercise {
             }
             let test_success = test_cmd.run("cargo test …")?;
             if !test_success {
-                run_bin(bin_name, output, cmd_runner)?;
+                run_bin(bin_name, cwd, output, cmd_runner)?;
                 return Ok(false);
             }
 
@@ -151,7 +160,7 @@ pub trait RunnableExercise {
         }
 
         let clippy_success = clippy_cmd.run("cargo clippy …")?;
-        let run_success = run_bin(bin_name, output, cmd_runner)?;
+        let run_success = run_bin(bin_name, cwd, output, cmd_runner)?;
 
         Ok(clippy_success && run_success)
     }