Check that all solutions run successfully

7 files changed, 169 insertions, 86 deletions

diff --git a/src/app_state.rs b/src/app_state.rs
index c7c090f..e9a5b10 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -11,7 +11,7 @@ use std::{
 use crate::{
     clear_terminal,
     embedded::EMBEDDED_FILES,
-    exercise::{Exercise, OUTPUT_CAPACITY},
+    exercise::{Exercise, RunnableExercise, OUTPUT_CAPACITY},
     info_file::ExerciseInfo,
     DEBUG_PROFILE,
 };
@@ -40,6 +40,25 @@ struct CargoMetadata {
     target_directory: PathBuf,
 }
 
+pub fn parse_target_dir() -> Result<PathBuf> {
+    // Get the target directory from Cargo.
+    let metadata_output = Command::new("cargo")
+        .arg("metadata")
+        .arg("-q")
+        .arg("--format-version")
+        .arg("1")
+        .arg("--no-deps")
+        .stdin(Stdio::null())
+        .stderr(Stdio::inherit())
+        .output()
+        .context(CARGO_METADATA_ERR)?
+        .stdout;
+
+    serde_json::de::from_slice::<CargoMetadata>(&metadata_output)
+        .context("Failed to read the field `target_directory` from the `cargo metadata` output")
+        .map(|metadata| metadata.target_directory)
+}
+
 pub struct AppState {
     current_exercise_ind: usize,
     exercises: Vec<Exercise>,
@@ -104,23 +123,7 @@ impl AppState {
         exercise_infos: Vec<ExerciseInfo>,
         final_message: String,
     ) -> Result<(Self, StateFileStatus)> {
-        // Get the target directory from Cargo.
-        let metadata_output = Command::new("cargo")
-            .arg("metadata")
-            .arg("-q")
-            .arg("--format-version")
-            .arg("1")
-            .arg("--no-deps")
-            .stdin(Stdio::null())
-            .stderr(Stdio::inherit())
-            .output()
-            .context(CARGO_METADATA_ERR)?
-            .stdout;
-        let target_dir = serde_json::de::from_slice::<CargoMetadata>(&metadata_output)
-            .context(
-                "Failed to read the field `target_directory` from the `cargo metadata` output",
-            )?
-            .target_directory;
+        let target_dir = parse_target_dir()?;
 
         let exercises = exercise_infos
             .into_iter()
@@ -381,7 +384,7 @@ impl AppState {
             write!(writer, "Running {exercise} ... ")?;
             writer.flush()?;
 
-            let success = exercise.run(&mut output, &self.target_dir)?;
+            let success = exercise.run_exercise(&mut output, &self.target_dir)?;
             if !success {
                 writeln!(writer, "{}\n", "FAILED".red())?;
 
diff --git a/src/cmd.rs b/src/cmd.rs
index b914ed8..6092f53 100644
--- a/src/cmd.rs
+++ b/src/cmd.rs
@@ -35,7 +35,7 @@ pub fn run_cmd(mut cmd: Command, description: &str, output: &mut Vec<u8>) -> Res
 pub struct CargoCmd<'a> {
     pub subcommand: &'a str,
     pub args: &'a [&'a str],
-    pub exercise_name: &'a str,
+    pub bin_name: &'a str,
     pub description: &'a str,
     /// RUSTFLAGS="-A warnings"
     pub hide_warnings: bool,
@@ -65,7 +65,7 @@ impl<'a> CargoCmd<'a> {
             .arg("always")
             .arg("-q")
             .arg("--bin")
-            .arg(self.exercise_name)
+            .arg(self.bin_name)
             .args(self.args);
 
         if self.hide_warnings {
diff --git a/src/dev/check.rs b/src/dev/check.rs
index 59352e9..6a3597c 100644
--- a/src/dev/check.rs
+++ b/src/dev/check.rs
@@ -2,12 +2,14 @@ use anyhow::{anyhow, bail, Context, Error, Result};
 use std::{
     cmp::Ordering,
     fs::{self, read_dir, OpenOptions},
-    io::Read,
+    io::{self, Read, Write},
     path::{Path, PathBuf},
 };
 
 use crate::{
+    app_state::parse_target_dir,
     cargo_toml::{append_bins, bins_start_end_ind, BINS_BUFFER_CAPACITY},
+    exercise::{RunnableExercise, OUTPUT_CAPACITY},
     info_file::{ExerciseInfo, InfoFile},
     CURRENT_FORMAT_VERSION, DEBUG_PROFILE,
 };
@@ -17,6 +19,29 @@ fn forbidden_char(input: &str) -> Option<char> {
     input.chars().find(|c| !c.is_alphanumeric() && *c != '_')
 }
 
+// Check that the Cargo.toml file is up-to-date.
+fn check_cargo_toml(
+    exercise_infos: &[ExerciseInfo],
+    current_cargo_toml: &str,
+    exercise_path_prefix: &[u8],
+) -> Result<()> {
+    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+
+    let old_bins = &current_cargo_toml.as_bytes()[bins_start_ind..bins_end_ind];
+    let mut new_bins = Vec::with_capacity(BINS_BUFFER_CAPACITY);
+    append_bins(&mut new_bins, exercise_infos, exercise_path_prefix);
+
+    if old_bins != new_bins {
+        if DEBUG_PROFILE {
+            bail!("The file `dev/Cargo.toml` is outdated. Please run `cargo run -- dev update` to update it");
+        }
+
+        bail!("The file `Cargo.toml` is outdated. Please run `rustlings dev update` to update it");
+    }
+
+    Ok(())
+}
+
 // Check the info of all exercises and return their paths in a set.
 fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<PathBuf>> {
     let mut names = hashbrown::HashSet::with_capacity(info_file.exercises.len());
@@ -136,24 +161,20 @@ fn check_exercises(info_file: &InfoFile) -> Result<()> {
     Ok(())
 }
 
-// Check that the Cargo.toml file is up-to-date.
-fn check_cargo_toml(
-    exercise_infos: &[ExerciseInfo],
-    current_cargo_toml: &str,
-    exercise_path_prefix: &[u8],
-) -> Result<()> {
-    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+fn check_solutions(info_file: &InfoFile) -> Result<()> {
+    let target_dir = parse_target_dir()?;
+    let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
 
-    let old_bins = &current_cargo_toml.as_bytes()[bins_start_ind..bins_end_ind];
-    let mut new_bins = Vec::with_capacity(BINS_BUFFER_CAPACITY);
-    append_bins(&mut new_bins, exercise_infos, exercise_path_prefix);
-
-    if old_bins != new_bins {
-        if DEBUG_PROFILE {
-            bail!("The file `dev/Cargo.toml` is outdated. Please run `cargo run -- dev update` to update it");
+    for exercise_info in &info_file.exercises {
+        let success = exercise_info.run_solution(&mut output, &target_dir)?;
+        if !success {
+            io::stderr().write_all(&output)?;
+
+            bail!(
+                "Failed to run the solution of the exercise {}",
+                exercise_info.name,
+            );
         }
-
-        bail!("The file `Cargo.toml` is outdated. Please run `rustlings dev update` to update it");
     }
 
     Ok(())
@@ -161,7 +182,6 @@ fn check_cargo_toml(
 
 pub fn check() -> Result<()> {
     let info_file = InfoFile::parse()?;
-    check_exercises(&info_file)?;
 
     // A hack to make `cargo run -- dev check` work when developing Rustlings.
     if DEBUG_PROFILE {
@@ -176,6 +196,9 @@ pub fn check() -> Result<()> {
         check_cargo_toml(&info_file.exercises, &current_cargo_toml, b"")?;
     }
 
+    check_exercises(&info_file)?;
+    check_solutions(&info_file)?;
+
     println!("\nEverything looks fine!");
 
     Ok(())
diff --git a/src/exercise.rs b/src/exercise.rs
index 4bc37cd..b6adc14 100644
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -17,6 +17,35 @@ use crate::{
 /// The initial capacity of the output buffer.
 pub const OUTPUT_CAPACITY: usize = 1 << 14;
 
+// Run an exercise binary and append its output to the `output` buffer.
+// Compilation must be done before calling this method.
+fn run_bin(bin_name: &str, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
+    writeln!(output, "{}", "Output".underlined())?;
+
+    // 7 = "/debug/".len()
+    let mut bin_path = PathBuf::with_capacity(target_dir.as_os_str().len() + 7 + bin_name.len());
+    bin_path.push(target_dir);
+    bin_path.push("debug");
+    bin_path.push(bin_name);
+
+    let success = run_cmd(Command::new(&bin_path), &bin_path.to_string_lossy(), output)?;
+
+    if !success {
+        // This output is important to show the user that something went wrong.
+        // Otherwise, calling something like `exit(1)` in an exercise without further output
+        // leaves the user confused about why the exercise isn't done yet.
+        writeln!(
+            output,
+            "{}",
+            "The exercise didn't run successfully (nonzero exit code)"
+                .bold()
+                .red(),
+        )?;
+    }
+
+    Ok(success)
+}
+
 /// See `info_file::ExerciseInfo`
 pub struct Exercise {
     pub dir: Option<&'static str>,
@@ -30,39 +59,25 @@ pub struct Exercise {
 }
 
 impl Exercise {
-    // Run the exercise's binary and append its output to the `output` buffer.
-    // Compilation should be done before calling this method.
-    fn run_bin(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
-        writeln!(output, "{}", "Output".underlined())?;
-
-        // 7 = "/debug/".len()
-        let mut bin_path =
-            PathBuf::with_capacity(target_dir.as_os_str().len() + 7 + self.name.len());
-        bin_path.push(target_dir);
-        bin_path.push("debug");
-        bin_path.push(self.name);
-
-        let success = run_cmd(Command::new(&bin_path), &bin_path.to_string_lossy(), output)?;
-
-        if !success {
-            // This output is important to show the user that something went wrong.
-            // Otherwise, calling something like `exit(1)` in an exercise without further output
-            // leaves the user confused about why the exercise isn't done yet.
-            writeln!(
-                output,
-                "{}",
-                "The exercise didn't run successfully (nonzero exit code)"
-                    .bold()
-                    .red(),
-            )?;
-        }
+    pub fn terminal_link(&self) -> StyledContent<TerminalFileLink<'_>> {
+        style(TerminalFileLink(self.path)).underlined().blue()
+    }
+}
 
-        Ok(success)
+impl Display for Exercise {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        self.path.fmt(f)
     }
+}
 
-    /// Compile, check and run the exercise.
-    /// The output is written to the `output` buffer after clearing it.
-    pub fn run(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
+pub trait RunnableExercise {
+    fn name(&self) -> &str;
+    fn strict_clippy(&self) -> bool;
+    fn test(&self) -> bool;
+
+    // Compile, check and run the exercise or its solution (depending on `bin_name´).
+    // The output is written to the `output` buffer after clearing it.
+    fn run(&self, bin_name: &str, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
         output.clear();
 
         // Developing the official Rustlings.
@@ -71,7 +86,7 @@ impl Exercise {
         let build_success = CargoCmd {
             subcommand: "build",
             args: &[],
-            exercise_name: self.name,
+            bin_name,
             description: "cargo build …",
             hide_warnings: false,
             target_dir,
@@ -87,7 +102,7 @@ impl Exercise {
         output.clear();
 
         // `--profile test` is required to also check code with `[cfg(test)]`.
-        let clippy_args: &[&str] = if self.strict_clippy {
+        let clippy_args: &[&str] = if self.strict_clippy() {
             &["--profile", "test", "--", "-D", "warnings"]
         } else {
             &["--profile", "test"]
@@ -95,7 +110,7 @@ impl Exercise {
         let clippy_success = CargoCmd {
             subcommand: "clippy",
             args: clippy_args,
-            exercise_name: self.name,
+            bin_name,
             description: "cargo clippy …",
             hide_warnings: false,
             target_dir,
@@ -107,14 +122,14 @@ impl Exercise {
             return Ok(false);
         }
 
-        if !self.test {
-            return self.run_bin(output, target_dir);
+        if !self.test() {
+            return run_bin(bin_name, output, target_dir);
         }
 
         let test_success = CargoCmd {
             subcommand: "test",
             args: &["--", "--color", "always", "--show-output"],
-            exercise_name: self.name,
+            bin_name,
             description: "cargo test …",
             // Hide warnings because they are shown by Clippy.
             hide_warnings: true,
@@ -124,18 +139,43 @@ impl Exercise {
         }
         .run()?;
 
-        let run_success = self.run_bin(output, target_dir)?;
+        let run_success = run_bin(bin_name, output, target_dir)?;
 
         Ok(test_success && run_success)
     }
 
-    pub fn terminal_link(&self) -> StyledContent<TerminalFileLink<'_>> {
-        style(TerminalFileLink(self.path)).underlined().blue()
+    /// Compile, check and run the exercise.
+    /// The output is written to the `output` buffer after clearing it.
+    #[inline]
+    fn run_exercise(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
+        self.run(self.name(), output, target_dir)
+    }
+
+    /// Compile, check and run the exercise's solution.
+    /// The output is written to the `output` buffer after clearing it.
+    fn run_solution(&self, output: &mut Vec<u8>, target_dir: &Path) -> Result<bool> {
+        let name = self.name();
+        let mut bin_name = String::with_capacity(name.len());
+        bin_name.push_str(name);
+        bin_name.push_str("_sol");
+
+        self.run(&bin_name, output, target_dir)
     }
 }
 
-impl Display for Exercise {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        self.path.fmt(f)
+impl RunnableExercise for Exercise {
+    #[inline]
+    fn name(&self) -> &str {
+        self.name
+    }
+
+    #[inline]
+    fn strict_clippy(&self) -> bool {
+        self.strict_clippy
+    }
+
+    #[inline]
+    fn test(&self) -> bool {
+        self.test
     }
 }
diff --git a/src/info_file.rs b/src/info_file.rs
index 5ea487f..f226f73 100644
--- a/src/info_file.rs
+++ b/src/info_file.rs
@@ -2,7 +2,7 @@ use anyhow::{bail, Context, Error, Result};
 use serde::Deserialize;
 use std::{fs, io::ErrorKind};
 
-use crate::embedded::EMBEDDED_FILES;
+use crate::{embedded::EMBEDDED_FILES, exercise::RunnableExercise};
 
 /// Deserialized from the `info.toml` file.
 #[derive(Deserialize)]
@@ -75,6 +75,23 @@ impl ExerciseInfo {
     }
 }
 
+impl RunnableExercise for ExerciseInfo {
+    #[inline]
+    fn name(&self) -> &str {
+        &self.name
+    }
+
+    #[inline]
+    fn strict_clippy(&self) -> bool {
+        self.strict_clippy
+    }
+
+    #[inline]
+    fn test(&self) -> bool {
+        self.test
+    }
+}
+
 /// The deserialized `info.toml` file.
 #[derive(Deserialize)]
 pub struct InfoFile {
diff --git a/src/run.rs b/src/run.rs
index 36899b9..899d0a9 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -4,14 +4,14 @@ use std::io::{self, Write};
 
 use crate::{
     app_state::{AppState, ExercisesProgress},
-    exercise::OUTPUT_CAPACITY,
+    exercise::{RunnableExercise, OUTPUT_CAPACITY},
     terminal_link::TerminalFileLink,
 };
 
 pub fn run(app_state: &mut AppState) -> Result<()> {
     let exercise = app_state.current_exercise();
     let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
-    let success = exercise.run(&mut output, app_state.target_dir())?;
+    let success = exercise.run_exercise(&mut output, app_state.target_dir())?;
 
     let mut stdout = io::stdout().lock();
     stdout.write_all(&output)?;
diff --git a/src/watch/state.rs b/src/watch/state.rs
index 14c3f01..dd43c56 100644
--- a/src/watch/state.rs
+++ b/src/watch/state.rs
@@ -8,7 +8,7 @@ use std::io::{self, StdoutLock, Write};
 use crate::{
     app_state::{AppState, ExercisesProgress},
     clear_terminal,
-    exercise::OUTPUT_CAPACITY,
+    exercise::{RunnableExercise, OUTPUT_CAPACITY},
     progress_bar::progress_bar,
     terminal_link::TerminalFileLink,
 };
@@ -54,7 +54,7 @@ impl<'a> WatchState<'a> {
         let success = self
             .app_state
             .current_exercise()
-            .run(&mut self.output, self.app_state.target_dir())?;
+            .run_exercise(&mut self.output, self.app_state.target_dir())?;
         if success {
             self.done_status =
                 if let Some(solution_path) = self.app_state.current_solution_path()? {