From 67fa01774223b08833c21baeb13bdec9e4a298a0 Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 01:56:01 +0200
Subject: [PATCH 1/6] Use os_pipe

---
 Cargo.lock         |  11 +++++
 Cargo.toml         |   1 +
 src/app_state.rs   |  13 +++++-
 src/exercise.rs    | 110 +++++++++++++++++++++++++++++++++++++++------
 src/main.rs        |   6 ++-
 src/run.rs         |  11 +++--
 src/watch/state.rs |  26 +++--------
 7 files changed, 135 insertions(+), 43 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 5f0b597..823fec3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -519,6 +519,16 @@ version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
+[[package]]
+name = "os_pipe"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57119c3b893986491ec9aa85056780d3a0f3cf4da7cc09dd3650dbd6c6738fb9"
+dependencies = [
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "parking_lot"
 version = "0.12.1"
@@ -677,6 +687,7 @@ dependencies = [
  "crossterm",
  "hashbrown",
  "notify-debouncer-mini",
+ "os_pipe",
  "predicates",
  "ratatui",
  "rustlings-macros",
diff --git a/Cargo.toml b/Cargo.toml
index f4615b1..31e7456 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -50,6 +50,7 @@ clap = { version = "4.5.4", features = ["derive"] }
 crossterm = "0.27.0"
 hashbrown = "0.14.3"
 notify-debouncer-mini = "0.4.1"
+os_pipe = "1.1.5"
 ratatui = "0.26.2"
 rustlings-macros = { path = "rustlings-macros", version = "6.0.0-beta.0" }
 serde.workspace = true
diff --git a/src/app_state.rs b/src/app_state.rs
index 33d3de2..4160f6e 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -11,7 +11,12 @@ use std::{
     process::{Command, Stdio},
 };
 
-use crate::{embedded::EMBEDDED_FILES, exercise::Exercise, info_file::ExerciseInfo, DEBUG_PROFILE};
+use crate::{
+    embedded::EMBEDDED_FILES,
+    exercise::{Exercise, OUTPUT_CAPACITY},
+    info_file::ExerciseInfo,
+    DEBUG_PROFILE,
+};
 
 const STATE_FILE_NAME: &str = ".rustlings-state.txt";
 const BAD_INDEX_ERR: &str = "The current exercise index is higher than the number of exercises";
@@ -302,11 +307,13 @@ impl AppState {
         let Some(ind) = self.next_pending_exercise_ind() else {
             writer.write_all(RERUNNING_ALL_EXERCISES_MSG)?;
 
+            let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
             for (exercise_ind, exercise) in self.exercises().iter().enumerate() {
                 writer.write_fmt(format_args!("Running {exercise} ... "))?;
                 writer.flush()?;
 
-                if !exercise.run()?.status.success() {
+                let success = exercise.run(&mut output)?;
+                if !success {
                     writer.write_fmt(format_args!("{}\n\n", "FAILED".red()))?;
 
                     self.current_exercise_ind = exercise_ind;
@@ -322,6 +329,8 @@ impl AppState {
                 }
 
                 writer.write_fmt(format_args!("{}\n", "ok".green()))?;
+
+                output.clear();
             }
 
             writer.execute(Clear(ClearType::All))?;
diff --git a/src/exercise.rs b/src/exercise.rs
index 45ac208..17cc8d7 100644
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -2,11 +2,42 @@ use anyhow::{Context, Result};
 use crossterm::style::{style, StyledContent, Stylize};
 use std::{
     fmt::{self, Display, Formatter},
-    path::Path,
-    process::{Command, Output},
+    io::{Read, Write},
+    process::Command,
 };
 
-use crate::{info_file::Mode, terminal_link::TerminalFileLink, DEBUG_PROFILE};
+use crate::{in_official_repo, info_file::Mode, terminal_link::TerminalFileLink, DEBUG_PROFILE};
+
+// TODO
+pub const OUTPUT_CAPACITY: usize = 1 << 12;
+
+fn run_command(mut cmd: Command, cmd_description: &str, output: &mut Vec<u8>) -> Result<bool> {
+    let (mut reader, writer) = os_pipe::pipe().with_context(|| {
+        format!("Failed to create a pipe to run the command `{cmd_description}``")
+    })?;
+
+    let mut handle = cmd
+        .stdout(writer.try_clone().with_context(|| {
+            format!("Failed to clone the pipe writer for the command `{cmd_description}`")
+        })?)
+        .stderr(writer)
+        .spawn()
+        .with_context(|| format!("Failed to run the command `{cmd_description}`"))?;
+
+    // Prevent pipe deadlock.
+    drop(cmd);
+
+    reader
+        .read_to_end(output)
+        .with_context(|| format!("Failed to read the output of the command `{cmd_description}`"))?;
+
+    output.push(b'\n');
+
+    handle
+        .wait()
+        .with_context(|| format!("Failed to wait on the command `{cmd_description}` to exit"))
+        .map(|status| status.success())
+}
 
 pub struct Exercise {
     pub dir: Option<&'static str>,
@@ -22,13 +53,30 @@ pub struct Exercise {
 }
 
 impl Exercise {
-    fn cargo_cmd(&self, command: &str, args: &[&str]) -> Result<Output> {
+    fn run_bin(&self, output: &mut Vec<u8>) -> Result<bool> {
+        writeln!(output, "{}", "Output".bold().magenta().underlined())?;
+
+        let bin_path = format!("target/debug/{}", self.name);
+        run_command(Command::new(&bin_path), &bin_path, output)
+    }
+
+    fn cargo_cmd(
+        &self,
+        command: &str,
+        args: &[&str],
+        cmd_description: &str,
+        output: &mut Vec<u8>,
+        dev: bool,
+    ) -> Result<bool> {
         let mut cmd = Command::new("cargo");
         cmd.arg(command);
 
         // A hack to make `cargo run` work when developing Rustlings.
-        if DEBUG_PROFILE && Path::new("tests").exists() {
-            cmd.arg("--manifest-path").arg("dev/Cargo.toml");
+        if dev {
+            cmd.arg("--manifest-path")
+                .arg("dev/Cargo.toml")
+                .arg("--target-dir")
+                .arg("target");
         }
 
         cmd.arg("--color")
@@ -36,15 +84,43 @@ impl Exercise {
             .arg("-q")
             .arg("--bin")
             .arg(self.name)
-            .args(args)
-            .output()
-            .context("Failed to run Cargo")
+            .args(args);
+
+        run_command(cmd, cmd_description, output)
     }
 
-    pub fn run(&self) -> Result<Output> {
+    fn cargo_cmd_with_bin_output(
+        &self,
+        command: &str,
+        args: &[&str],
+        cmd_description: &str,
+        output: &mut Vec<u8>,
+        dev: bool,
+    ) -> Result<bool> {
+        // Discard the output of `cargo build` because it will be shown again by the Cargo command.
+        output.clear();
+
+        let cargo_cmd_success = self.cargo_cmd(command, args, cmd_description, output, dev)?;
+
+        let run_success = self.run_bin(output)?;
+
+        Ok(cargo_cmd_success && run_success)
+    }
+
+    pub fn run(&self, output: &mut Vec<u8>) -> Result<bool> {
+        output.clear();
+
+        // Developing the official Rustlings.
+        let dev = DEBUG_PROFILE && in_official_repo();
+
+        let build_success = self.cargo_cmd("build", &[], "cargo build …", output, dev)?;
+        if !build_success {
+            return Ok(false);
+        }
+
         match self.mode {
-            Mode::Run => self.cargo_cmd("run", &[]),
-            Mode::Test => self.cargo_cmd(
+            Mode::Run => self.run_bin(output),
+            Mode::Test => self.cargo_cmd_with_bin_output(
                 "test",
                 &[
                     "--",
@@ -54,10 +130,16 @@ impl Exercise {
                     "--format",
                     "pretty",
                 ],
+                "cargo test …",
+                output,
+                dev,
             ),
-            Mode::Clippy => self.cargo_cmd(
+            Mode::Clippy => self.cargo_cmd_with_bin_output(
                 "clippy",
-                &["--", "-D", "warnings", "-D", "clippy::float_cmp"],
+                &["--", "-D", "warnings"],
+                "cargo clippy …",
+                output,
+                dev,
             ),
         }
     }
diff --git a/src/main.rs b/src/main.rs
index 790fff6..a928504 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -75,10 +75,14 @@ enum Subcommands {
     Dev(DevCommands),
 }
 
+fn in_official_repo() -> bool {
+    Path::new("dev/rustlings-repo.txt").exists()
+}
+
 fn main() -> Result<()> {
     let args = Args::parse();
 
-    if !DEBUG_PROFILE && Path::new("dev/rustlings-repo.txt").exists() {
+    if !DEBUG_PROFILE && in_official_repo() {
         bail!("{OLD_METHOD_ERR}");
     }
 
diff --git a/src/run.rs b/src/run.rs
index a2b6972..1db8dcb 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -4,20 +4,19 @@ use std::io::{self, Write};
 
 use crate::{
     app_state::{AppState, ExercisesProgress},
+    exercise::OUTPUT_CAPACITY,
     terminal_link::TerminalFileLink,
 };
 
 pub fn run(app_state: &mut AppState) -> Result<()> {
     let exercise = app_state.current_exercise();
-    let output = exercise.run()?;
+    let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
+    let success = exercise.run(&mut output)?;
 
     let mut stdout = io::stdout().lock();
-    stdout.write_all(&output.stdout)?;
-    stdout.write_all(b"\n")?;
-    stdout.write_all(&output.stderr)?;
-    stdout.flush()?;
+    stdout.write_all(&output)?;
 
-    if !output.status.success() {
+    if !success {
         app_state.set_pending(app_state.current_exercise_ind())?;
 
         bail!(
diff --git a/src/watch/state.rs b/src/watch/state.rs
index 5f4abf3..df492dc 100644
--- a/src/watch/state.rs
+++ b/src/watch/state.rs
@@ -8,6 +8,7 @@ use std::io::{self, StdoutLock, Write};
 
 use crate::{
     app_state::{AppState, ExercisesProgress},
+    exercise::OUTPUT_CAPACITY,
     progress_bar::progress_bar,
     terminal_link::TerminalFileLink,
 };
@@ -21,8 +22,7 @@ enum DoneStatus {
 pub struct WatchState<'a> {
     writer: StdoutLock<'a>,
     app_state: &'a mut AppState,
-    stdout: Option<Vec<u8>>,
-    stderr: Option<Vec<u8>>,
+    output: Vec<u8>,
     show_hint: bool,
     done_status: DoneStatus,
     manual_run: bool,
@@ -35,8 +35,7 @@ impl<'a> WatchState<'a> {
         Self {
             writer,
             app_state,
-            stdout: None,
-            stderr: None,
+            output: Vec::with_capacity(OUTPUT_CAPACITY),
             show_hint: false,
             done_status: DoneStatus::Pending,
             manual_run,
@@ -51,11 +50,8 @@ impl<'a> WatchState<'a> {
     pub fn run_current_exercise(&mut self) -> Result<()> {
         self.show_hint = false;
 
-        let output = self.app_state.current_exercise().run()?;
-        self.stdout = Some(output.stdout);
-
-        if output.status.success() {
-            self.stderr = None;
+        let success = self.app_state.current_exercise().run(&mut self.output)?;
+        if success {
             self.done_status =
                 if let Some(solution_path) = self.app_state.current_solution_path()? {
                     DoneStatus::DoneWithSolution(solution_path)
@@ -66,7 +62,6 @@ impl<'a> WatchState<'a> {
             self.app_state
                 .set_pending(self.app_state.current_exercise_ind())?;
 
-            self.stderr = Some(output.stderr);
             self.done_status = DoneStatus::Pending;
         }
 
@@ -116,16 +111,7 @@ impl<'a> WatchState<'a> {
 
         self.writer.execute(Clear(ClearType::All))?;
 
-        if let Some(stdout) = &self.stdout {
-            self.writer.write_all(stdout)?;
-            self.writer.write_all(b"\n")?;
-        }
-
-        if let Some(stderr) = &self.stderr {
-            self.writer.write_all(stderr)?;
-            self.writer.write_all(b"\n")?;
-        }
-
+        self.writer.write_all(&self.output)?;
         self.writer.write_all(b"\n")?;
 
         if self.show_hint {

From f92d45fa685e308c009cdf09d341bda41fcf9c52 Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 02:03:26 +0200
Subject: [PATCH 2/6] Use write macros instead of write_fmt

---
 src/app_state.rs   |  6 +++---
 src/list/state.rs  |  3 +--
 src/run.rs         |  7 ++++---
 src/watch/state.rs | 37 ++++++++++++++++++++-----------------
 4 files changed, 28 insertions(+), 25 deletions(-)

diff --git a/src/app_state.rs b/src/app_state.rs
index 4160f6e..11ac8ee 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -309,12 +309,12 @@ impl AppState {
 
             let mut output = Vec::with_capacity(OUTPUT_CAPACITY);
             for (exercise_ind, exercise) in self.exercises().iter().enumerate() {
-                writer.write_fmt(format_args!("Running {exercise} ... "))?;
+                write!(writer, "Running {exercise} ... ")?;
                 writer.flush()?;
 
                 let success = exercise.run(&mut output)?;
                 if !success {
-                    writer.write_fmt(format_args!("{}\n\n", "FAILED".red()))?;
+                    writeln!(writer, "{}\n", "FAILED".red())?;
 
                     self.current_exercise_ind = exercise_ind;
 
@@ -328,7 +328,7 @@ impl AppState {
                     return Ok(ExercisesProgress::Pending);
                 }
 
-                writer.write_fmt(format_args!("{}\n", "ok".green()))?;
+                writeln!(writer, "{}", "ok".green())?;
 
                 output.clear();
             }
diff --git a/src/list/state.rs b/src/list/state.rs
index 0253bb9..19a77fe 100644
--- a/src/list/state.rs
+++ b/src/list/state.rs
@@ -231,8 +231,7 @@ impl<'a> UiState<'a> {
             .context("Invalid selection index")?;
 
         let exercise_path = self.app_state.reset_exercise_by_ind(ind)?;
-        self.message
-            .write_fmt(format_args!("The exercise {exercise_path} has been reset"))?;
+        write!(self.message, "The exercise {exercise_path} has been reset")?;
 
         Ok(self.with_updated_rows())
     }
diff --git a/src/run.rs b/src/run.rs
index 1db8dcb..cbc9ad7 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -25,11 +25,12 @@ pub fn run(app_state: &mut AppState) -> Result<()> {
         );
     }
 
-    stdout.write_fmt(format_args!(
-        "{}{}\n",
+    writeln!(
+        stdout,
+        "{}{}",
         "✓ Successfully ran ".green(),
         exercise.path.green(),
-    ))?;
+    )?;
 
     if let Some(solution_path) = app_state.current_solution_path()? {
         println!(
diff --git a/src/watch/state.rs b/src/watch/state.rs
index df492dc..40c01bf 100644
--- a/src/watch/state.rs
+++ b/src/watch/state.rs
@@ -88,19 +88,18 @@ impl<'a> WatchState<'a> {
         self.writer.write_all(b"\n")?;
 
         if self.manual_run {
-            self.writer.write_fmt(format_args!("{}un/", 'r'.bold()))?;
+            write!(self.writer, "{}un/", 'r'.bold())?;
         }
 
         if !matches!(self.done_status, DoneStatus::Pending) {
-            self.writer.write_fmt(format_args!("{}ext/", 'n'.bold()))?;
+            write!(self.writer, "{}ext/", 'n'.bold())?;
         }
 
         if !self.show_hint {
-            self.writer.write_fmt(format_args!("{}int/", 'h'.bold()))?;
+            write!(self.writer, "{}int/", 'h'.bold())?;
         }
 
-        self.writer
-            .write_fmt(format_args!("{}ist/{}uit? ", 'l'.bold(), 'q'.bold()))?;
+        write!(self.writer, "{}ist/{}uit? ", 'l'.bold(), 'q'.bold())?;
 
         self.writer.flush()
     }
@@ -115,28 +114,31 @@ impl<'a> WatchState<'a> {
         self.writer.write_all(b"\n")?;
 
         if self.show_hint {
-            self.writer.write_fmt(format_args!(
-                "{}\n{}\n\n",
+            writeln!(
+                self.writer,
+                "{}\n{}\n",
                 "Hint".bold().cyan().underlined(),
                 self.app_state.current_exercise().hint,
-            ))?;
+            )?;
         }
 
         if !matches!(self.done_status, DoneStatus::Pending) {
-            self.writer.write_fmt(format_args!(
-                "{}\n\n",
+            writeln!(
+                self.writer,
+                "{}\n",
                 "Exercise done ✓
 When you are done experimenting, enter `n` or `next` to go to the next exercise 🦀"
                     .bold()
                     .green(),
-            ))?;
+            )?;
         }
 
         if let DoneStatus::DoneWithSolution(solution_path) = &self.done_status {
-            self.writer.write_fmt(format_args!(
-                "A solution file can be found at {}\n\n",
+            writeln!(
+                self.writer,
+                "A solution file can be found at {}\n",
                 style(TerminalFileLink(solution_path)).underlined().green()
-            ))?;
+            )?;
         }
 
         let line_width = size()?.0;
@@ -145,10 +147,11 @@ When you are done experimenting, enter `n` or `next` to go to the next exercise
             self.app_state.exercises().len() as u16,
             line_width,
         )?;
-        self.writer.write_fmt(format_args!(
-            "{progress_bar}Current exercise: {}\n",
+        writeln!(
+            self.writer,
+            "{progress_bar}Current exercise: {}",
             self.app_state.current_exercise().terminal_link(),
-        ))?;
+        )?;
 
         self.show_prompt()?;
 

From 2af0cd9ccef07edf27abf7046dbe15e32d1b476d Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 03:25:45 +0200
Subject: [PATCH 3/6] Replace `mode` by `test` and `strict_clippy`

---
 info.toml                       | 143 +++++++++++---------------------
 src/app_state.rs                |   5 +-
 src/dev/new.rs                  |  13 ++-
 src/exercise.rs                 | 131 +++++++++++++++++------------
 src/info_file.rs                |  22 ++---
 tests/fixture/failure/info.toml |   3 +-
 tests/fixture/state/info.toml   |   5 +-
 tests/fixture/success/info.toml |   3 +-
 8 files changed, 147 insertions(+), 178 deletions(-)

diff --git a/info.toml b/info.toml
index d5369d5..1494472 100644
--- a/info.toml
+++ b/info.toml
@@ -39,7 +39,7 @@ https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md
 [[exercises]]
 name = "intro1"
 dir = "00_intro"
-mode = "run"
+test = false
 # TODO: Fix hint
 hint = """
 Remove the `I AM NOT DONE` comment in the `exercises/intro00/intro1.rs` file
@@ -48,7 +48,7 @@ to move on to the next exercise."""
 [[exercises]]
 name = "intro2"
 dir = "00_intro"
-mode = "run"
+test = false
 hint = """
 The compiler is informing us that we've got the name of the print macro wrong, and has suggested an alternative."""
 
@@ -57,7 +57,7 @@ The compiler is informing us that we've got the name of the print macro wrong, a
 [[exercises]]
 name = "variables1"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 The declaration in the first line in the main function is missing a keyword
 that is needed in Rust to create a new variable binding."""
@@ -65,7 +65,7 @@ that is needed in Rust to create a new variable binding."""
 [[exercises]]
 name = "variables2"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 The compiler message is saying that Rust cannot infer the type that the
 variable binding `x` has with what is given here.
@@ -84,7 +84,7 @@ What if `x` is the same type as `10`? What if it's a different type?"""
 [[exercises]]
 name = "variables3"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 Oops! In this exercise, we have a variable binding that we've created on in the
 first line in the `main` function, and we're trying to use it in the next line,
@@ -98,7 +98,7 @@ programming language -- thankfully the Rust compiler has caught this for us!"""
 [[exercises]]
 name = "variables4"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 In Rust, variable bindings are immutable by default. But here we're trying
 to reassign a different value to `x`! There's a keyword we can use to make
@@ -107,7 +107,7 @@ a variable binding mutable instead."""
 [[exercises]]
 name = "variables5"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 In `variables4` we already learned how to make an immutable variable mutable
 using a special keyword. Unfortunately this doesn't help us much in this
@@ -125,7 +125,7 @@ Try to solve this exercise afterwards using this technique."""
 [[exercises]]
 name = "variables6"
 dir = "01_variables"
-mode = "run"
+test = false
 hint = """
 We know about variables and mutability, but there is another important type of
 variable available: constants.
@@ -145,7 +145,7 @@ https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#constants
 [[exercises]]
 name = "functions1"
 dir = "02_functions"
-mode = "run"
+test = false
 hint = """
 This main function is calling a function that it expects to exist, but the
 function doesn't exist. It expects this function to have the name `call_me`.
@@ -155,7 +155,7 @@ Sounds a lot like `main`, doesn't it?"""
 [[exercises]]
 name = "functions2"
 dir = "02_functions"
-mode = "run"
+test = false
 hint = """
 Rust requires that all parts of a function's signature have type annotations,
 but `call_me` is missing the type annotation of `num`."""
@@ -163,7 +163,7 @@ but `call_me` is missing the type annotation of `num`."""
 [[exercises]]
 name = "functions3"
 dir = "02_functions"
-mode = "run"
+test = false
 hint = """
 This time, the function *declaration* is okay, but there's something wrong
 with the place where we're calling the function."""
@@ -171,7 +171,7 @@ with the place where we're calling the function."""
 [[exercises]]
 name = "functions4"
 dir = "02_functions"
-mode = "run"
+test = false
 hint = """
 The error message points to the function `sale_price` and says it expects a type
 after the `->`. This is where the function's return type should be -- take a
@@ -180,7 +180,7 @@ look at the `is_even` function for an example!"""
 [[exercises]]
 name = "functions5"
 dir = "02_functions"
-mode = "run"
+test = false
 hint = """
 This is a really common error that can be fixed by removing one character.
 It happens because Rust distinguishes between expressions and statements:
@@ -199,7 +199,6 @@ They are not the same. There are two solutions:
 [[exercises]]
 name = "if1"
 dir = "03_if"
-mode = "test"
 hint = """
 It's possible to do this in one line if you would like!
 
@@ -215,7 +214,6 @@ Remember in Rust that:
 [[exercises]]
 name = "if2"
 dir = "03_if"
-mode = "test"
 hint = """
 For that first compiler error, it's important in Rust that each conditional
 block returns the same type! To get the tests passing, you will need a couple
@@ -224,7 +222,6 @@ conditions checking different input values."""
 [[exercises]]
 name = "if3"
 dir = "03_if"
-mode = "test"
 hint = """
 In Rust, every arm of an `if` expression has to return the same type of value.
 Make sure the type is consistent across all arms."""
@@ -234,7 +231,6 @@ Make sure the type is consistent across all arms."""
 [[exercises]]
 name = "quiz1"
 dir = "quizzes"
-mode = "test"
 hint = "No hints this time ;)"
 
 # PRIMITIVE TYPES
@@ -242,19 +238,19 @@ hint = "No hints this time ;)"
 [[exercises]]
 name = "primitive_types1"
 dir = "04_primitive_types"
-mode = "run"
+test = false
 hint = "No hints this time ;)"
 
 [[exercises]]
 name = "primitive_types2"
 dir = "04_primitive_types"
-mode = "run"
+test = false
 hint = "No hints this time ;)"
 
 [[exercises]]
 name = "primitive_types3"
 dir = "04_primitive_types"
-mode = "run"
+test = false
 hint = """
 There's a shorthand to initialize Arrays with a certain size that does not
 require you to type in 100 items (but you certainly can if you want!).
@@ -270,7 +266,6 @@ for `a.len() >= 100`?"""
 [[exercises]]
 name = "primitive_types4"
 dir = "04_primitive_types"
-mode = "test"
 hint = """
 Take a look at the 'Understanding Ownership -> Slices -> Other Slices' section
 of the book: https://doc.rust-lang.org/book/ch04-03-slices.html and use the
@@ -285,7 +280,7 @@ https://doc.rust-lang.org/nomicon/coercions.html"""
 [[exercises]]
 name = "primitive_types5"
 dir = "04_primitive_types"
-mode = "run"
+test = false
 hint = """
 Take a look at the 'Data Types -> The Tuple Type' section of the book:
 https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
@@ -298,7 +293,6 @@ of the tuple. You can do it!!"""
 [[exercises]]
 name = "primitive_types6"
 dir = "04_primitive_types"
-mode = "test"
 hint = """
 While you could use a destructuring `let` for the tuple here, try
 indexing into it instead, as explained in the last example of the
@@ -311,7 +305,6 @@ Now you have another tool in your toolbox!"""
 [[exercises]]
 name = "vecs1"
 dir = "05_vecs"
-mode = "test"
 hint = """
 In Rust, there are two ways to define a Vector.
 1. One way is to use the `Vec::new()` function to create a new vector
@@ -326,7 +319,6 @@ of the Rust book to learn more.
 [[exercises]]
 name = "vecs2"
 dir = "05_vecs"
-mode = "test"
 hint = """
 In the first function we are looping over the Vector and getting a reference to
 one `element` at a time.
@@ -349,7 +341,6 @@ What do you think is the more commonly used pattern under Rust developers?
 [[exercises]]
 name = "move_semantics1"
 dir = "06_move_semantics"
-mode = "test"
 hint = """
 So you've got the "cannot borrow immutable local variable `vec` as mutable"
 error on the line where we push an element to the vector, right?
@@ -363,7 +354,6 @@ happens!"""
 [[exercises]]
 name = "move_semantics2"
 dir = "06_move_semantics"
-mode = "test"
 hint = """
 When running this exercise for the first time, you'll notice an error about
 "borrow of moved value". In Rust, when an argument is passed to a function and
@@ -384,7 +374,6 @@ try them all:
 [[exercises]]
 name = "move_semantics3"
 dir = "06_move_semantics"
-mode = "test"
 hint = """
 The difference between this one and the previous ones is that the first line
 of `fn fill_vec` that had `let mut vec = vec;` is no longer there. You can,
@@ -394,7 +383,6 @@ an existing binding to be a mutable binding instead of an immutable one :)"""
 [[exercises]]
 name = "move_semantics4"
 dir = "06_move_semantics"
-mode = "test"
 hint = """
 Stop reading whenever you feel like you have enough direction :) Or try
 doing one step and then fixing the compiler errors that result!
@@ -408,7 +396,6 @@ So the end goal is to:
 [[exercises]]
 name = "move_semantics5"
 dir = "06_move_semantics"
-mode = "test"
 hint = """
 Carefully reason about the range in which each mutable reference is in
 scope. Does it help to update the value of referent (`x`) immediately after
@@ -420,7 +407,7 @@ https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#mutable-ref
 [[exercises]]
 name = "move_semantics6"
 dir = "06_move_semantics"
-mode = "run"
+test = false
 hint = """
 To find the answer, you can consult the book section "References and Borrowing":
 https://doc.rust-lang.org/stable/book/ch04-02-references-and-borrowing.html
@@ -441,7 +428,6 @@ Another hint: it has to do with the `&` character."""
 [[exercises]]
 name = "structs1"
 dir = "07_structs"
-mode = "test"
 hint = """
 Rust has more than one type of struct. Three actually, all variants are used to
 package related data together.
@@ -461,7 +447,6 @@ https://doc.rust-lang.org/book/ch05-01-defining-structs.html"""
 [[exercises]]
 name = "structs2"
 dir = "07_structs"
-mode = "test"
 hint = """
 Creating instances of structs is easy, all you need to do is assign some values
 to its fields.
@@ -473,7 +458,6 @@ https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-ins
 [[exercises]]
 name = "structs3"
 dir = "07_structs"
-mode = "test"
 hint = """
 For `is_international`: What makes a package international? Seems related to
 the places it goes through right?
@@ -489,13 +473,13 @@ https://doc.rust-lang.org/book/ch05-03-method-syntax.html"""
 [[exercises]]
 name = "enums1"
 dir = "08_enums"
-mode = "run"
+test = false
 hint = "No hints this time ;)"
 
 [[exercises]]
 name = "enums2"
 dir = "08_enums"
-mode = "run"
+test = false
 hint = """
 You can create enumerations that have different variants with different types
 such as no data, anonymous structs, a single string, tuples, ...etc"""
@@ -503,7 +487,6 @@ such as no data, anonymous structs, a single string, tuples, ...etc"""
 [[exercises]]
 name = "enums3"
 dir = "08_enums"
-mode = "test"
 hint = """
 As a first step, you can define enums to compile this code without errors.
 
@@ -517,7 +500,7 @@ to get value in the variant."""
 [[exercises]]
 name = "strings1"
 dir = "09_strings"
-mode = "run"
+test = false
 hint = """
 The `current_favorite_color` function is currently returning a string slice
 with the `'static` lifetime. We know this because the data of the string lives
@@ -531,7 +514,7 @@ another way that uses the `From` trait."""
 [[exercises]]
 name = "strings2"
 dir = "09_strings"
-mode = "run"
+test = false
 hint = """
 Yes, it would be really easy to fix this by just changing the value bound to
 `word` to be a string slice instead of a `String`, wouldn't it?? There is a way
@@ -546,7 +529,6 @@ https://doc.rust-lang.org/stable/book/ch15-02-deref.html#implicit-deref-coercion
 [[exercises]]
 name = "strings3"
 dir = "09_strings"
-mode = "test"
 hint = """
 There's tons of useful standard library functions for strings. Let's try and use some of them:
 https://doc.rust-lang.org/std/string/struct.String.html#method.trim
@@ -557,7 +539,7 @@ the string slice into an owned string, which you can then freely extend."""
 [[exercises]]
 name = "strings4"
 dir = "09_strings"
-mode = "run"
+test = false
 hint = "No hints this time ;)"
 
 # MODULES
@@ -565,7 +547,7 @@ hint = "No hints this time ;)"
 [[exercises]]
 name = "modules1"
 dir = "10_modules"
-mode = "run"
+test = false
 hint = """
 Everything is private in Rust by default-- but there's a keyword we can use
 to make something public! The compiler error should point to the thing that
@@ -574,7 +556,7 @@ needs to be public."""
 [[exercises]]
 name = "modules2"
 dir = "10_modules"
-mode = "run"
+test = false
 hint = """
 The delicious_snacks module is trying to present an external interface that is
 different than its internal structure (the `fruits` and `veggies` modules and
@@ -586,7 +568,7 @@ Learn more at https://doc.rust-lang.org/book/ch07-04-bringing-paths-into-scope-w
 [[exercises]]
 name = "modules3"
 dir = "10_modules"
-mode = "run"
+test = false
 hint = """
 `UNIX_EPOCH` and `SystemTime` are declared in the `std::time` module. Add a
 `use` statement for these two to bring them into scope. You can use nested
@@ -597,7 +579,6 @@ paths or the glob operator to bring these two in using only one line."""
 [[exercises]]
 name = "hashmaps1"
 dir = "11_hashmaps"
-mode = "test"
 hint = """
 Hint 1: Take a look at the return type of the function to figure out
         the type for the `basket`.
@@ -609,7 +590,6 @@ Hint 2: Number of fruits should be at least 5. And you have to put
 [[exercises]]
 name = "hashmaps2"
 dir = "11_hashmaps"
-mode = "test"
 hint = """
 Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
 Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
@@ -618,7 +598,6 @@ Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-
 [[exercises]]
 name = "hashmaps3"
 dir = "11_hashmaps"
-mode = "test"
 hint = """
 Hint 1: Use the `entry()` and `or_insert()` methods of `HashMap` to insert
         entries corresponding to each team in the scores table.
@@ -636,7 +615,6 @@ Learn more at https://doc.rust-lang.org/book/ch08-03-hash-maps.html#updating-a-v
 [[exercises]]
 name = "quiz2"
 dir = "quizzes"
-mode = "test"
 hint = "No hints this time ;)"
 
 # OPTIONS
@@ -644,7 +622,6 @@ hint = "No hints this time ;)"
 [[exercises]]
 name = "options1"
 dir = "12_options"
-mode = "test"
 hint = """
 Options can have a `Some` value, with an inner value, or a `None` value,
 without an inner value.
@@ -656,7 +633,6 @@ it doesn't panic in your face later?"""
 [[exercises]]
 name = "options2"
 dir = "12_options"
-mode = "test"
 hint = """
 Check out:
 
@@ -673,7 +649,7 @@ Also see `Option::flatten`
 [[exercises]]
 name = "options3"
 dir = "12_options"
-mode = "run"
+test = false
 hint = """
 The compiler says a partial move happened in the `match` statement. How can
 this be avoided? The compiler shows the correction needed.
@@ -686,7 +662,6 @@ https://doc.rust-lang.org/std/keyword.ref.html"""
 [[exercises]]
 name = "errors1"
 dir = "13_error_handling"
-mode = "test"
 hint = """
 `Ok` and `Err` are the two variants of `Result`, so what the tests are saying
 is that `generate_nametag_text` should return a `Result` instead of an `Option`.
@@ -702,7 +677,6 @@ To make this change, you'll need to:
 [[exercises]]
 name = "errors2"
 dir = "13_error_handling"
-mode = "test"
 hint = """
 One way to handle this is using a `match` statement on
 `item_quantity.parse::<i32>()` where the cases are `Ok(something)` and
@@ -718,7 +692,7 @@ and give it a try!"""
 [[exercises]]
 name = "errors3"
 dir = "13_error_handling"
-mode = "run"
+test = false
 hint = """
 If other functions can return a `Result`, why shouldn't `main`? It's a fairly
 common convention to return something like `Result<(), ErrorType>` from your
@@ -730,7 +704,6 @@ positive results."""
 [[exercises]]
 name = "errors4"
 dir = "13_error_handling"
-mode = "test"
 hint = """
 `PositiveNonzeroInteger::new` is always creating a new instance and returning
 an `Ok` result.
@@ -742,7 +715,7 @@ everything is... okay :)"""
 [[exercises]]
 name = "errors5"
 dir = "13_error_handling"
-mode = "run"
+test = false
 hint = """
 There are two different possible `Result` types produced within `main()`, which
 are propagated using `?` operators. How do we declare a return type from
@@ -766,7 +739,6 @@ https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reen
 [[exercises]]
 name = "errors6"
 dir = "13_error_handling"
-mode = "test"
 hint = """
 This exercise uses a completed version of `PositiveNonzeroInteger` from
 errors4.
@@ -788,7 +760,7 @@ https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
 [[exercises]]
 name = "generics1"
 dir = "14_generics"
-mode = "run"
+test = false
 hint = """
 Vectors in Rust make use of generics to create dynamically sized arrays of any
 type.
@@ -798,7 +770,6 @@ You need to tell the compiler what type we are pushing onto this vector."""
 [[exercises]]
 name = "generics2"
 dir = "14_generics"
-mode = "test"
 hint = """
 Currently we are wrapping only values of type `u32`.
 
@@ -812,7 +783,6 @@ If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html
 [[exercises]]
 name = "traits1"
 dir = "15_traits"
-mode = "test"
 hint = """
 A discussion about Traits in Rust can be found at:
 https://doc.rust-lang.org/book/ch10-02-traits.html
@@ -821,7 +791,6 @@ https://doc.rust-lang.org/book/ch10-02-traits.html
 [[exercises]]
 name = "traits2"
 dir = "15_traits"
-mode = "test"
 hint = """
 Notice how the trait takes ownership of `self`, and returns `Self`.
 
@@ -834,7 +803,6 @@ the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""
 [[exercises]]
 name = "traits3"
 dir = "15_traits"
-mode = "test"
 hint = """
 Traits can have a default implementation for functions. Structs that implement
 the trait can then use the default version of these functions if they choose not
@@ -846,7 +814,6 @@ See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#def
 [[exercises]]
 name = "traits4"
 dir = "15_traits"
-mode = "test"
 hint = """
 Instead of using concrete types as parameters you can use traits. Try replacing
 the '??' with 'impl <what goes here?>'
@@ -857,7 +824,7 @@ See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#tra
 [[exercises]]
 name = "traits5"
 dir = "15_traits"
-mode = "run"
+test = false
 hint = """
 To ensure a parameter implements multiple traits use the '+ syntax'. Try
 replacing the '??' with 'impl <> + <>'.
@@ -870,7 +837,6 @@ See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#spe
 [[exercises]]
 name = "quiz3"
 dir = "quizzes"
-mode = "test"
 hint = """
 To find the best solution to this challenge you're going to need to think back
 to your knowledge of traits, specifically 'Trait Bound Syntax'
@@ -882,7 +848,7 @@ You may also need this: `use std::fmt::Display;`."""
 [[exercises]]
 name = "lifetimes1"
 dir = "16_lifetimes"
-mode = "run"
+test = false
 hint = """
 Let the compiler guide you. Also take a look at the book if you need help:
 https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html"""
@@ -890,7 +856,7 @@ https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html"""
 [[exercises]]
 name = "lifetimes2"
 dir = "16_lifetimes"
-mode = "run"
+test = false
 hint = """
 Remember that the generic lifetime `'a` will get the concrete lifetime that is
 equal to the smaller of the lifetimes of `x` and `y`.
@@ -904,7 +870,7 @@ inner block:
 [[exercises]]
 name = "lifetimes3"
 dir = "16_lifetimes"
-mode = "run"
+test = false
 hint = """
 If you use a lifetime annotation in a struct's fields, where else does it need
 to be added?"""
@@ -914,7 +880,6 @@ to be added?"""
 [[exercises]]
 name = "tests1"
 dir = "17_tests"
-mode = "test"
 hint = """
 You don't even need to write any code to test -- you can just test values and
 run that, even though you wouldn't do that in real life. :)
@@ -929,7 +894,6 @@ ones pass, and which ones fail :)"""
 [[exercises]]
 name = "tests2"
 dir = "17_tests"
-mode = "test"
 hint = """
 Like the previous exercise, you don't need to write any code to get this test
 to compile and run.
@@ -942,7 +906,6 @@ argument comes first and which comes second!"""
 [[exercises]]
 name = "tests3"
 dir = "17_tests"
-mode = "test"
 hint = """
 You can call a function right where you're passing arguments to `assert!`. So
 you could do something like `assert!(having_fun())`.
@@ -953,7 +916,6 @@ what you're doing using `!`, like `assert!(!having_fun())`."""
 [[exercises]]
 name = "tests4"
 dir = "17_tests"
-mode = "test"
 hint = """
 We expect method `Rectangle::new()` to panic for negative values.
 
@@ -967,7 +929,6 @@ https://doc.rust-lang.org/stable/book/ch11-01-writing-tests.html#checking-for-pa
 [[exercises]]
 name = "iterators1"
 dir = "18_iterators"
-mode = "test"
 hint = """
 Step 1:
 
@@ -990,7 +951,6 @@ https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
 [[exercises]]
 name = "iterators2"
 dir = "18_iterators"
-mode = "test"
 hint = """
 Step 1:
 
@@ -1016,7 +976,6 @@ powerful and very general. Rust just needs to know the desired type."""
 [[exercises]]
 name = "iterators3"
 dir = "18_iterators"
-mode = "test"
 hint = """
 The `divide` function needs to return the correct error when even division is
 not possible.
@@ -1035,7 +994,6 @@ powerful! It can make the solution to this exercise infinitely easier."""
 [[exercises]]
 name = "iterators4"
 dir = "18_iterators"
-mode = "test"
 hint = """
 In an imperative language, you might write a `for` loop that updates a mutable
 variable. Or, you might write code utilizing recursion and a match clause. In
@@ -1047,7 +1005,6 @@ Hint 2: Check out the `fold` and `rfold` methods!"""
 [[exercises]]
 name = "iterators5"
 dir = "18_iterators"
-mode = "test"
 hint = """
 The documentation for the `std::iter::Iterator` trait contains numerous methods
 that would be helpful here.
@@ -1066,7 +1023,6 @@ a different method that could make your code more compact than using `fold`."""
 [[exercises]]
 name = "box1"
 dir = "19_smart_pointers"
-mode = "test"
 hint = """
 Step 1:
 
@@ -1090,7 +1046,6 @@ definition and try other types!
 [[exercises]]
 name = "rc1"
 dir = "19_smart_pointers"
-mode = "test"
 hint = """
 This is a straightforward exercise to use the `Rc<T>` type. Each `Planet` has
 ownership of the `Sun`, and uses `Rc::clone()` to increment the reference count
@@ -1109,7 +1064,7 @@ See more at: https://doc.rust-lang.org/book/ch15-04-rc.html
 [[exercises]]
 name = "arc1"
 dir = "19_smart_pointers"
-mode = "run"
+test = false
 hint = """
 Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
 to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
@@ -1127,7 +1082,6 @@ https://doc.rust-lang.org/stable/book/ch16-00-concurrency.html
 [[exercises]]
 name = "cow1"
 dir = "19_smart_pointers"
-mode = "test"
 hint = """
 If `Cow` already owns the data it doesn't need to clone it when `to_mut()` is
 called.
@@ -1141,7 +1095,7 @@ on the `Cow` type.
 [[exercises]]
 name = "threads1"
 dir = "20_threads"
-mode = "run"
+test = false
 hint = """
 `JoinHandle` is a struct that is returned from a spawned thread:
 https://doc.rust-lang.org/std/thread/fn.spawn.html
@@ -1159,7 +1113,7 @@ https://doc.rust-lang.org/std/thread/struct.JoinHandle.html
 [[exercises]]
 name = "threads2"
 dir = "20_threads"
-mode = "run"
+test = false
 hint = """
 `Arc` is an Atomic Reference Counted pointer that allows safe, shared access
 to **immutable** data. But we want to *change* the number of `jobs_completed`
@@ -1181,7 +1135,6 @@ https://doc.rust-lang.org/book/ch16-03-shared-state.html#sharing-a-mutext-betwee
 [[exercises]]
 name = "threads3"
 dir = "20_threads"
-mode = "test"
 hint = """
 An alternate way to handle concurrency between threads is to use an `mpsc`
 (multiple producer, single consumer) channel to communicate.
@@ -1200,7 +1153,7 @@ See https://doc.rust-lang.org/book/ch16-02-message-passing.html for more info.
 [[exercises]]
 name = "macros1"
 dir = "21_macros"
-mode = "run"
+test = false
 hint = """
 When you call a macro, you need to add something special compared to a
 regular function call. If you're stuck, take a look at what's inside
@@ -1209,7 +1162,7 @@ regular function call. If you're stuck, take a look at what's inside
 [[exercises]]
 name = "macros2"
 dir = "21_macros"
-mode = "run"
+test = false
 hint = """
 Macros don't quite play by the same rules as the rest of Rust, in terms of
 what's available where.
@@ -1220,7 +1173,7 @@ Unlike other things in Rust, the order of "where you define a macro" versus
 [[exercises]]
 name = "macros3"
 dir = "21_macros"
-mode = "run"
+test = false
 hint = """
 In order to use a macro outside of its module, you need to do something
 special to the module to lift the macro out into its parent.
@@ -1231,7 +1184,7 @@ exported macros, if you've seen any of those around."""
 [[exercises]]
 name = "macros4"
 dir = "21_macros"
-mode = "run"
+test = false
 hint = """
 You only need to add a single character to make this compile.
 
@@ -1248,7 +1201,8 @@ https://veykril.github.io/tlborm/"""
 [[exercises]]
 name = "clippy1"
 dir = "22_clippy"
-mode = "clippy"
+test = false
+strict_clippy = true
 hint = """
 Rust stores the highest precision version of any long or infinite precision
 mathematical constants in the Rust standard library:
@@ -1264,14 +1218,16 @@ appropriate replacement constant from `std::f32::consts`..."""
 [[exercises]]
 name = "clippy2"
 dir = "22_clippy"
-mode = "clippy"
+test = false
+strict_clippy = true
 hint = """
 `for` loops over `Option` values are more clearly expressed as an `if let`"""
 
 [[exercises]]
 name = "clippy3"
 dir = "22_clippy"
-mode = "clippy"
+test = false
+strict_clippy = true
 hint = "No hints this time!"
 
 # TYPE CONVERSIONS
@@ -1279,7 +1235,6 @@ hint = "No hints this time!"
 [[exercises]]
 name = "using_as"
 dir = "23_conversions"
-mode = "test"
 hint = """
 Use the `as` operator to cast one of the operands in the last line of the
 `average` function into the expected return type."""
@@ -1287,14 +1242,12 @@ Use the `as` operator to cast one of the operands in the last line of the
 [[exercises]]
 name = "from_into"
 dir = "23_conversions"
-mode = "test"
 hint = """
 Follow the steps provided right before the `From` implementation"""
 
 [[exercises]]
 name = "from_str"
 dir = "23_conversions"
-mode = "test"
 hint = """
 The implementation of `FromStr` should return an `Ok` with a `Person` object,
 or an `Err` with an error if the string is not valid.
@@ -1315,7 +1268,6 @@ https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reen
 [[exercises]]
 name = "try_from_into"
 dir = "23_conversions"
-mode = "test"
 hint = """
 Follow the steps provided right before the `TryFrom` implementation.
 You can also use the example at
@@ -1338,6 +1290,5 @@ Challenge: Can you make the `TryFrom` implementations generic over many integer
 [[exercises]]
 name = "as_ref_mut"
 dir = "23_conversions"
-mode = "test"
 hint = """
 Add `AsRef<str>` or `AsMut<u32>` as a trait bound to the functions."""
diff --git a/src/app_state.rs b/src/app_state.rs
index 11ac8ee..476b5a9 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -112,7 +112,8 @@ impl AppState {
                     dir,
                     name,
                     path,
-                    mode: exercise_info.mode,
+                    test: exercise_info.test,
+                    strict_clippy: exercise_info.strict_clippy,
                     hint,
                     done: false,
                 }
@@ -329,8 +330,6 @@ impl AppState {
                 }
 
                 writeln!(writer, "{}", "ok".green())?;
-
-                output.clear();
             }
 
             writer.execute(Clear(ClearType::All))?;
diff --git a/src/dev/new.rs b/src/dev/new.rs
index 82aba42..8f87010 100644
--- a/src/dev/new.rs
+++ b/src/dev/new.rs
@@ -99,10 +99,15 @@ name = "???"
 # Otherwise, the path is `exercises/NAME.rs`
 # dir = "???"
 
-# The mode to run the exercise in.
-# The mode "test" (preferred) runs the exercise's tests.
-# The mode "run" only checks if the exercise compiles and runs it.
-mode = "test"
+# Rustlings expects the exercise to contain tests and run them.
+# You can optionally disable testing by setting `test` to `false` (the default is `true`).
+# In that case, the exercise will be considered done when it just successfully compiles.
+# test = true
+
+# Rustlings will always run Clippy on exercises.
+# You can optionally set `strict_clippy` to `true` (the default is `false`) to only consider
+# the exercise as done when there are no warnings left.
+# strict_clippy = false
 
 # A multi-line hint to be shown to users on request.
 hint = """???"""
diff --git a/src/exercise.rs b/src/exercise.rs
index 17cc8d7..366dc2b 100644
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -3,24 +3,38 @@ use crossterm::style::{style, StyledContent, Stylize};
 use std::{
     fmt::{self, Display, Formatter},
     io::{Read, Write},
-    process::Command,
+    process::{Command, Stdio},
 };
 
-use crate::{in_official_repo, info_file::Mode, terminal_link::TerminalFileLink, DEBUG_PROFILE};
+use crate::{in_official_repo, terminal_link::TerminalFileLink, DEBUG_PROFILE};
 
 // TODO
 pub const OUTPUT_CAPACITY: usize = 1 << 12;
 
-fn run_command(mut cmd: Command, cmd_description: &str, output: &mut Vec<u8>) -> Result<bool> {
+fn run_command(
+    mut cmd: Command,
+    cmd_description: &str,
+    output: &mut Vec<u8>,
+    stderr: bool,
+) -> Result<bool> {
     let (mut reader, writer) = os_pipe::pipe().with_context(|| {
         format!("Failed to create a pipe to run the command `{cmd_description}``")
     })?;
 
+    let (stdout, stderr) = if stderr {
+        (
+            Stdio::from(writer.try_clone().with_context(|| {
+                format!("Failed to clone the pipe writer for the command `{cmd_description}`")
+            })?),
+            Stdio::from(writer),
+        )
+    } else {
+        (Stdio::from(writer), Stdio::null())
+    };
+
     let mut handle = cmd
-        .stdout(writer.try_clone().with_context(|| {
-            format!("Failed to clone the pipe writer for the command `{cmd_description}`")
-        })?)
-        .stderr(writer)
+        .stdout(stdout)
+        .stderr(stderr)
         .spawn()
         .with_context(|| format!("Failed to run the command `{cmd_description}`"))?;
 
@@ -45,8 +59,8 @@ pub struct Exercise {
     pub name: &'static str,
     // Exercise's path
     pub path: &'static str,
-    // The mode of the exercise
-    pub mode: Mode,
+    pub test: bool,
+    pub strict_clippy: bool,
     // The hint text associated with the exercise
     pub hint: String,
     pub done: bool,
@@ -54,10 +68,22 @@ pub struct Exercise {
 
 impl Exercise {
     fn run_bin(&self, output: &mut Vec<u8>) -> Result<bool> {
-        writeln!(output, "{}", "Output".bold().magenta().underlined())?;
+        writeln!(output, "{}", "Output".underlined())?;
 
         let bin_path = format!("target/debug/{}", self.name);
-        run_command(Command::new(&bin_path), &bin_path, output)
+        let success = run_command(Command::new(&bin_path), &bin_path, output, true)?;
+
+        if !success {
+            writeln!(
+                output,
+                "{}",
+                "The exercise didn't run successfully (nonzero exit code)"
+                    .bold()
+                    .red()
+            )?;
+        }
+
+        Ok(success)
     }
 
     fn cargo_cmd(
@@ -67,6 +93,7 @@ impl Exercise {
         cmd_description: &str,
         output: &mut Vec<u8>,
         dev: bool,
+        stderr: bool,
     ) -> Result<bool> {
         let mut cmd = Command::new("cargo");
         cmd.arg(command);
@@ -86,25 +113,7 @@ impl Exercise {
             .arg(self.name)
             .args(args);
 
-        run_command(cmd, cmd_description, output)
-    }
-
-    fn cargo_cmd_with_bin_output(
-        &self,
-        command: &str,
-        args: &[&str],
-        cmd_description: &str,
-        output: &mut Vec<u8>,
-        dev: bool,
-    ) -> Result<bool> {
-        // Discard the output of `cargo build` because it will be shown again by the Cargo command.
-        output.clear();
-
-        let cargo_cmd_success = self.cargo_cmd(command, args, cmd_description, output, dev)?;
-
-        let run_success = self.run_bin(output)?;
-
-        Ok(cargo_cmd_success && run_success)
+        run_command(cmd, cmd_description, output, stderr)
     }
 
     pub fn run(&self, output: &mut Vec<u8>) -> Result<bool> {
@@ -113,35 +122,49 @@ impl Exercise {
         // Developing the official Rustlings.
         let dev = DEBUG_PROFILE && in_official_repo();
 
-        let build_success = self.cargo_cmd("build", &[], "cargo build …", output, dev)?;
+        let build_success = self.cargo_cmd("build", &[], "cargo build …", output, dev, true)?;
         if !build_success {
             return Ok(false);
         }
 
-        match self.mode {
-            Mode::Run => self.run_bin(output),
-            Mode::Test => self.cargo_cmd_with_bin_output(
-                "test",
-                &[
-                    "--",
-                    "--color",
-                    "always",
-                    "--nocapture",
-                    "--format",
-                    "pretty",
-                ],
-                "cargo test …",
-                output,
-                dev,
-            ),
-            Mode::Clippy => self.cargo_cmd_with_bin_output(
-                "clippy",
-                &["--", "-D", "warnings"],
-                "cargo clippy …",
-                output,
-                dev,
-            ),
+        // Discard the output of `cargo build` because it will be shown again by the Cargo command.
+        output.clear();
+
+        let clippy_args: &[&str] = if self.strict_clippy {
+            &["--", "-D", "warnings"]
+        } else {
+            &[]
+        };
+        let clippy_success =
+            self.cargo_cmd("clippy", clippy_args, "cargo clippy …", output, dev, true)?;
+        if !clippy_success {
+            return Ok(false);
         }
+
+        if !self.test {
+            return self.run_bin(output);
+        }
+
+        let test_success = self.cargo_cmd(
+            "test",
+            &[
+                "--",
+                "--color",
+                "always",
+                "--nocapture",
+                "--format",
+                "pretty",
+            ],
+            "cargo test …",
+            output,
+            dev,
+            // Hide warnings because they are shown by Clippy.
+            false,
+        )?;
+
+        let run_success = self.run_bin(output)?;
+
+        Ok(test_success && run_success)
     }
 
     pub fn terminal_link(&self) -> StyledContent<TerminalFileLink<'_>> {
diff --git a/src/info_file.rs b/src/info_file.rs
index 6938cd0..dbe4f08 100644
--- a/src/info_file.rs
+++ b/src/info_file.rs
@@ -2,18 +2,6 @@ use anyhow::{bail, Context, Error, Result};
 use serde::Deserialize;
 use std::{fs, io::ErrorKind};
 
-// The mode of the exercise.
-#[derive(Deserialize, Copy, Clone)]
-#[serde(rename_all = "lowercase")]
-pub enum Mode {
-    // The exercise should be compiled as a binary
-    Run,
-    // The exercise should be compiled as a test harness
-    Test,
-    // The exercise should be linted with clippy
-    Clippy,
-}
-
 // Deserialized from the `info.toml` file.
 #[derive(Deserialize)]
 pub struct ExerciseInfo {
@@ -21,11 +9,17 @@ pub struct ExerciseInfo {
     pub name: String,
     // The exercise's directory inside the `exercises` directory
     pub dir: Option<String>,
-    // The mode of the exercise
-    pub mode: Mode,
+    #[serde(default = "default_true")]
+    pub test: bool,
+    #[serde(default)]
+    pub strict_clippy: bool,
     // The hint text associated with the exercise
     pub hint: String,
 }
+#[inline]
+const fn default_true() -> bool {
+    true
+}
 
 impl ExerciseInfo {
     pub fn path(&self) -> String {
diff --git a/tests/fixture/failure/info.toml b/tests/fixture/failure/info.toml
index ef99a07..554607a 100644
--- a/tests/fixture/failure/info.toml
+++ b/tests/fixture/failure/info.toml
@@ -2,10 +2,9 @@ format_version = 1
 
 [[exercises]]
 name = "compFailure"
-mode = "run"
+test = false
 hint = ""
 
 [[exercises]]
 name = "testFailure"
-mode = "test"
 hint = "Hello!"
diff --git a/tests/fixture/state/info.toml b/tests/fixture/state/info.toml
index eec24ea..ff0b932 100644
--- a/tests/fixture/state/info.toml
+++ b/tests/fixture/state/info.toml
@@ -2,15 +2,14 @@ format_version = 1
 
 [[exercises]]
 name = "pending_exercise"
-mode = "run"
+test = false
 hint = """"""
 
 [[exercises]]
 name = "pending_test_exercise"
-mode = "test"
 hint = """"""
 
 [[exercises]]
 name = "finished_exercise"
-mode = "run"
+test = false
 hint = """"""
diff --git a/tests/fixture/success/info.toml b/tests/fixture/success/info.toml
index 88650ec..d66d7d4 100644
--- a/tests/fixture/success/info.toml
+++ b/tests/fixture/success/info.toml
@@ -2,10 +2,9 @@ format_version = 1
 
 [[exercises]]
 name = "compSuccess"
-mode = "run"
+test = false
 hint = """"""
 
 [[exercises]]
 name = "testSuccess"
-mode = "test"
 hint = """"""

From d26f47ddddaabcde36d5cb02ec220ccd1c141f10 Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 03:27:41 +0200
Subject: [PATCH 4/6] Fix tests

---
 tests/fixture/failure/exercises/compNoExercise.rs      | 3 +--
 tests/fixture/failure/exercises/testFailure.rs         | 2 ++
 tests/fixture/failure/exercises/testNotPassed.rs       | 2 ++
 tests/fixture/state/exercises/finished_exercise.rs     | 6 +-----
 tests/fixture/state/exercises/pending_exercise.rs      | 6 +-----
 tests/fixture/state/exercises/pending_test_exercise.rs | 2 ++
 tests/fixture/success/exercises/testSuccess.rs         | 2 ++
 7 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/tests/fixture/failure/exercises/compNoExercise.rs b/tests/fixture/failure/exercises/compNoExercise.rs
index f79c691..f328e4d 100644
--- a/tests/fixture/failure/exercises/compNoExercise.rs
+++ b/tests/fixture/failure/exercises/compNoExercise.rs
@@ -1,2 +1 @@
-fn main() {
-}
+fn main() {}
diff --git a/tests/fixture/failure/exercises/testFailure.rs b/tests/fixture/failure/exercises/testFailure.rs
index b33a5d2..fcbcf90 100644
--- a/tests/fixture/failure/exercises/testFailure.rs
+++ b/tests/fixture/failure/exercises/testFailure.rs
@@ -1,3 +1,5 @@
+fn main() {}
+
 #[test]
 fn passing() {
     asset!(true);
diff --git a/tests/fixture/failure/exercises/testNotPassed.rs b/tests/fixture/failure/exercises/testNotPassed.rs
index a9fe88d..de0d61c 100644
--- a/tests/fixture/failure/exercises/testNotPassed.rs
+++ b/tests/fixture/failure/exercises/testNotPassed.rs
@@ -1,3 +1,5 @@
+fn main() {}
+
 #[test]
 fn not_passing() {
     assert!(false);
diff --git a/tests/fixture/state/exercises/finished_exercise.rs b/tests/fixture/state/exercises/finished_exercise.rs
index 016b827..f328e4d 100644
--- a/tests/fixture/state/exercises/finished_exercise.rs
+++ b/tests/fixture/state/exercises/finished_exercise.rs
@@ -1,5 +1 @@
-// fake_exercise
-
-fn main() {
-
-}
+fn main() {}
diff --git a/tests/fixture/state/exercises/pending_exercise.rs b/tests/fixture/state/exercises/pending_exercise.rs
index 016b827..f328e4d 100644
--- a/tests/fixture/state/exercises/pending_exercise.rs
+++ b/tests/fixture/state/exercises/pending_exercise.rs
@@ -1,5 +1 @@
-// fake_exercise
-
-fn main() {
-
-}
+fn main() {}
diff --git a/tests/fixture/state/exercises/pending_test_exercise.rs b/tests/fixture/state/exercises/pending_test_exercise.rs
index 2002ef1..718e1db 100644
--- a/tests/fixture/state/exercises/pending_test_exercise.rs
+++ b/tests/fixture/state/exercises/pending_test_exercise.rs
@@ -1,2 +1,4 @@
+fn main() {}
+
 #[test]
 fn it_works() {}
diff --git a/tests/fixture/success/exercises/testSuccess.rs b/tests/fixture/success/exercises/testSuccess.rs
index 7139b50..4296cf6 100644
--- a/tests/fixture/success/exercises/testSuccess.rs
+++ b/tests/fixture/success/exercises/testSuccess.rs
@@ -1,3 +1,5 @@
+fn main() {}
+
 #[test]
 fn passing() {
     println!("THIS TEST TOO SHALL PASS");

From 428998a4cf74246b0a1da4b8013b504d86cdabeb Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 03:28:44 +0200
Subject: [PATCH 5/6] Quicker response to file changes

---
 src/watch.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/watch.rs b/src/watch.rs
index 5ebe526..1e22f59 100644
--- a/src/watch.rs
+++ b/src/watch.rs
@@ -51,7 +51,7 @@ pub fn watch(
     // Otherwise, the file watcher exits.
     let _debouncer_guard = if let Some(exercise_paths) = notify_exercise_paths {
         let mut debouncer = new_debouncer(
-            Duration::from_secs(1),
+            Duration::from_millis(500),
             DebounceEventHandler {
                 tx: tx.clone(),
                 exercise_paths,

From 1f1a62d83ef9398a1a31c904a2ef6d81f5455e59 Mon Sep 17 00:00:00 2001
From: mo8it <mo8it@proton.me>
Date: Thu, 25 Apr 2024 14:43:02 +0200
Subject: [PATCH 6/6] Raise the output capacity

---
 src/exercise.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/exercise.rs b/src/exercise.rs
index 366dc2b..21ae582 100644
--- a/src/exercise.rs
+++ b/src/exercise.rs
@@ -8,8 +8,7 @@ use std::{
 
 use crate::{in_official_repo, terminal_link::TerminalFileLink, DEBUG_PROFILE};
 
-// TODO
-pub const OUTPUT_CAPACITY: usize = 1 << 12;
+pub const OUTPUT_CAPACITY: usize = 1 << 14;
 
 fn run_command(
     mut cmd: Command,