feat: Add a --nocapture option to display test harnesses' outputs

This new feature can be accessed by invoking rustlings with --nocapture.

Both unit and integration tests added.

closes rust-lang#262

BREAKING CHANGES:
The following function take a new boolean argument:
	* `run`
	* `verify`
	* `test`
	* `compile_and_test`

info.toml

@@ -802,7 +802,7 @@ name = "try_from_into"
 path = "exercises/conversions/try_from_into.rs"
 mode = "test"
 hint = """
-Follow the steps provided right before the `From` implementation.
+Follow the steps provided right before the `TryFrom` implementation.
 You can also use the example at https://doc.rust-lang.org/std/convert/trait.TryFrom.html"""
 
 [[exercises]]
@@ -819,4 +819,4 @@ mode = "test"
 hint = """
 The implementation of FromStr should return an Ok with a Person object,
 or an Err with a string if the string is not valid.
-This is a some like an `try_from_into` exercise."""
+This is almost like the `try_from_into` exercise."""

src/exercise.rs

@@ -11,15 +11,21 @@ const I_AM_DONE_REGEX: &str = r"(?m)^\s*///?\s*I\s+AM\s+NOT\s+DONE";
 const CONTEXT: usize = 2;
 const CLIPPY_CARGO_TOML_PATH: &str = "./exercises/clippy/Cargo.toml";
 
+// Get a temporary file name that is hopefully unique to this process
+#[inline]
 fn temp_file() -> String {
     format!("./temp_{}", process::id())
 }
 
+// The mode of the exercise.
 #[derive(Deserialize, Copy, Clone)]
 #[serde(rename_all = "lowercase")]
 pub enum Mode {
+    // Indicates that the exercise should be compiled as a binary
     Compile,
+    // Indicates that the exercise should be compiled as a test harness
     Test,
+    // Indicates that the exercise should be linted with clippy
     Clippy,
 }
 
@@ -28,41 +34,60 @@ pub struct ExerciseList {
     pub exercises: Vec<Exercise>,
 }
 
+// A representation of a rustlings exercise.
+// This is deserialized from the accompanying info.toml file
 #[derive(Deserialize)]
 pub struct Exercise {
+    // Name of the exercise
     pub name: String,
+    // The path to the file containing the exercise's source code
     pub path: PathBuf,
+    // The mode of the exercise (Test, Compile, or Clippy)
     pub mode: Mode,
+    // The hint text associated with the exercise
     pub hint: String,
 }
 
+// An enum to track of the state of an Exercise.
+// An Exercise can be either Done or Pending
 #[derive(PartialEq, Debug)]
 pub enum State {
+    // The state of the exercise once it's been completed
     Done,
+    // The state of the exercise while it's not completed yet
     Pending(Vec<ContextLine>),
 }
 
+// The context information of a pending exercise
 #[derive(PartialEq, Debug)]
 pub struct ContextLine {
+    // The source code that is still pending completion
     pub line: String,
+    // The line number of the source code still pending completion
     pub number: usize,
+    // Whether or not this is important
     pub important: bool,
 }
 
+// The result of compiling an exercise
 pub struct CompiledExercise<'a> {
     exercise: &'a Exercise,
     _handle: FileHandle,
 }
 
 impl<'a> CompiledExercise<'a> {
+    // Run the compiled exercise
     pub fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
         self.exercise.run()
     }
 }
 
+// A representation of an already executed binary
 #[derive(Debug)]
 pub struct ExerciseOutput {
+    // The textual contents of the standard output of the binary
     pub stdout: String,
+    // The textual contents of the standard error of the binary
     pub stderr: String,
 }
 
@@ -140,7 +165,11 @@ path = "{}.rs""#,
     }
 
     fn run(&self) -> Result<ExerciseOutput, ExerciseOutput> {
-        let cmd = Command::new(&temp_file())
+        let arg = match self.mode {
+            Mode::Test => "--show-output",
+            _ => ""
+        };
+        let cmd = Command::new(&temp_file()).arg(arg)
             .output()
             .expect("Failed to run 'run' command");
 
@@ -205,6 +234,7 @@ impl Display for Exercise {
     }
 }
 
+#[inline]
 fn clean() {
     let _ignored = remove_file(&temp_file());
 }
@@ -280,4 +310,16 @@ mod test {
 
         assert_eq!(exercise.state(), State::Done);
     }
+
+    #[test]
+    fn test_exercise_with_output() {
+        let exercise = Exercise {
+            name: "finished_exercise".into(),
+            path: PathBuf::from("tests/fixture/success/testSuccess.rs"),
+            mode: Mode::Test,
+            hint: String::new(),
+        };
+        let out = exercise.compile().unwrap().run().unwrap();
+        assert!(out.stdout.contains("THIS TEST TOO SHALL PASS"));
+    }
 }

src/main.rs

@@ -28,10 +28,9 @@ fn main() {
         .author("Olivia Hugger, Carol Nichols")
         .about("Rustlings is a collection of small exercises to get you used to writing and reading Rust code")
         .arg(
-            Arg::with_name("verbose")
-                .short("V")
-                .long("verbose")
-                .help("Show tests' standard output")
+            Arg::with_name("nocapture")
+                .long("nocapture")
+                .help("Show outputs from the test exercises")
         )
         .subcommand(
             SubCommand::with_name("verify")
@@ -87,6 +86,7 @@ fn main() {
 
     let toml_str = &fs::read_to_string("info.toml").unwrap();
     let exercises = toml::from_str::<ExerciseList>(toml_str).unwrap().exercises;
+    let verbose = matches.is_present("nocapture");
 
     if let Some(ref matches) = matches.subcommand_matches("run") {
         let name = matches.value_of("name").unwrap();
@@ -98,7 +98,7 @@ fn main() {
             std::process::exit(1)
         });
 
-        run(&exercise).unwrap_or_else(|_| std::process::exit(1));
+        run(&exercise, verbose).unwrap_or_else(|_| std::process::exit(1));
     }
 
     if let Some(ref matches) = matches.subcommand_matches("hint") {
@@ -116,10 +116,10 @@ fn main() {
     }
 
     if matches.subcommand_matches("verify").is_some() {
-        verify(&exercises).unwrap_or_else(|_| std::process::exit(1));
+        verify(&exercises, verbose).unwrap_or_else(|_| std::process::exit(1));
     }
 
-    if matches.subcommand_matches("watch").is_some() && watch(&exercises).is_ok() {
+    if matches.subcommand_matches("watch").is_some() && watch(&exercises, verbose).is_ok() {
         println!(
             "{emoji} All exercises completed! {emoji}",
             emoji = Emoji("🎉", "★")
@@ -161,7 +161,7 @@ fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
     });
 }
 
-fn watch(exercises: &[Exercise]) -> notify::Result<()> {
+fn watch(exercises: &[Exercise], verbose: bool) -> notify::Result<()> {
     /* Clears the terminal with an ANSI escape code.
     Works in UNIX and newer Windows terminals. */
     fn clear_screen() {
@@ -176,7 +176,7 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
     clear_screen();
 
     let to_owned_hint = |t: &Exercise| t.hint.to_owned();
-    let failed_exercise_hint = match verify(exercises.iter()) {
+    let failed_exercise_hint = match verify(exercises.iter(), verbose) {
         Ok(_) => return Ok(()),
         Err(exercise) => Arc::new(Mutex::new(Some(to_owned_hint(exercise)))),
     };
@@ -191,7 +191,7 @@ fn watch(exercises: &[Exercise]) -> notify::Result<()> {
                             .iter()
                             .skip_while(|e| !filepath.ends_with(&e.path));
                         clear_screen();
-                        match verify(pending_exercises) {
+                        match verify(pending_exercises, verbose) {
                             Ok(_) => return Ok(()),
                             Err(exercise) => {
                                 let mut failed_exercise_hint = failed_exercise_hint.lock().unwrap();

src/run.rs

@@ -2,15 +2,22 @@ use crate::exercise::{Exercise, Mode};
 use crate::verify::test;
 use indicatif::ProgressBar;
 
-pub fn run(exercise: &Exercise) -> Result<(), ()> {
+// Invoke the rust compiler on the path of the given exercise,
+// and run the ensuing binary.
+// The verbose argument helps determine whether or not to show
+// the output from the test harnesses (if the mode of the exercise is test)
+pub fn run(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
     match exercise.mode {
-        Mode::Test => test(exercise)?,
+        Mode::Test => test(exercise, verbose)?,
         Mode::Compile => compile_and_run(exercise)?,
         Mode::Clippy => compile_and_run(exercise)?,
     }
     Ok(())
 }
 
+// Invoke the rust compiler on the path of the given exercise
+// and run the ensuing binary.
+// This is strictly for non-test binaries, so output is displayed
 fn compile_and_run(exercise: &Exercise) -> Result<(), ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Compiling {}...", exercise).as_str());

src/verify.rs

@@ -2,10 +2,18 @@ use crate::exercise::{CompiledExercise, Exercise, Mode, State};
 use console::style;
 use indicatif::ProgressBar;
 
-pub fn verify<'a>(start_at: impl IntoIterator<Item = &'a Exercise>) -> Result<(), &'a Exercise> {
+// Verify that the provided container of Exercise objects
+// can be compiled and run without any failures.
+// Any such failures will be reported to the end user.
+// If the Exercise being verified is a test, the verbose boolean
+// determines whether or not the test harness outputs are displayed.
+pub fn verify<'a>(
+    start_at: impl IntoIterator<Item = &'a Exercise>,
+    verbose: bool
+) -> Result<(), &'a Exercise> {
     for exercise in start_at {
         let compile_result = match exercise.mode {
-            Mode::Test => compile_and_test(&exercise, RunMode::Interactive),
+            Mode::Test => compile_and_test(&exercise, RunMode::Interactive, verbose),
             Mode::Compile => compile_and_run_interactively(&exercise),
             Mode::Clippy => compile_only(&exercise),
         };
@@ -21,11 +29,13 @@ enum RunMode {
     NonInteractive,
 }
 
-pub fn test(exercise: &Exercise) -> Result<(), ()> {
-    compile_and_test(exercise, RunMode::NonInteractive)?;
+// Compile and run the resulting test harness of the given Exercise
+pub fn test(exercise: &Exercise, verbose: bool) -> Result<(), ()> {
+    compile_and_test(exercise, RunMode::NonInteractive, verbose)?;
     Ok(())
 }
 
+// Invoke the rust compiler without running the resulting binary
 fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
@@ -38,6 +48,7 @@ fn compile_only(exercise: &Exercise) -> Result<bool, ()> {
     Ok(prompt_for_completion(&exercise, None))
 }
 
+// Compile the given Exercise and run the resulting binary in an interactive mode
 fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Compiling {}...", exercise).as_str());
@@ -63,7 +74,11 @@ fn compile_and_run_interactively(exercise: &Exercise) -> Result<bool, ()> {
     Ok(prompt_for_completion(&exercise, Some(output.stdout)))
 }
 
-fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()> {
+// Compile the given Exercise as a test harness and display
+// the output if verbose is set to true
+fn compile_and_test(
+    exercise: &Exercise, run_mode: RunMode, verbose: bool
+) -> Result<bool, ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Testing {}...", exercise).as_str());
     progress_bar.enable_steady_tick(100);
@@ -73,7 +88,10 @@ fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()>
     progress_bar.finish_and_clear();
 
     match result {
-        Ok(_) => {
+        Ok(output) => {
+            if verbose {
+                println!("{}", output.stdout);
+            }
             success!("Successfully tested {}", &exercise);
             if let RunMode::Interactive = run_mode {
                 Ok(prompt_for_completion(&exercise, None))
@@ -92,6 +110,8 @@ fn compile_and_test(exercise: &Exercise, run_mode: RunMode) -> Result<bool, ()>
     }
 }
 
+// Compile the given Exercise and return an object with information
+// about the state of the compilation
 fn compile<'a, 'b>(
     exercise: &'a Exercise,
     progress_bar: &'b ProgressBar,

tests/fixture/success/testSuccess.rs

@@ -1,4 +1,5 @@
 #[test]
 fn passing() {
+    println!("THIS TEST TOO SHALL PASS");
     assert!(true);
 }

tests/integration_tests.rs

@@ -159,3 +159,25 @@ fn run_test_exercise_does_not_prompt() {
         .code(0)
         .stdout(predicates::str::contains("I AM NOT DONE").not());
 }
+
+#[test]
+fn run_single_test_success_with_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["--nocapture", "r", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS"));
+}
+
+#[test]
+fn run_single_test_success_without_output() {
+    Command::cargo_bin("rustlings")
+        .unwrap()
+        .args(&["r", "testSuccess"])
+        .current_dir("tests/fixture/success/")
+        .assert()
+        .code(0)
+        .stdout(predicates::str::contains("THIS TEST TOO SHALL PAS").not());
+}