Intro Exercise: Hello World

Cargo.toml

@@ -1,6 +1,9 @@
 # Don't edit the `bin` list manually. Run `rustlings dev update` after changing
 # exercises or solutions.
-bin = []
+bin = [
+  { name = "intro1", path = "exercises/00_intro/intro1.rs" },
+  { name = "intro1_sol", path = "solutions/00_intro/intro1.rs" },
+]
 
 [package]
 name = "ratlings"

exercises/00_intro/intro1.rs

@@ -0,0 +1,36 @@
+use ratatui::{DefaultTerminal, Frame};
+use std::io::IsTerminal;
+
+// Do not modify this line
+fn main() -> std::io::Result<()> {
+    // TODO: run the TUI app.
+    // ratatui::run(app)
+    todo!("run the TUI app.")
+}
+
+fn app(terminal: &mut DefaultTerminal) -> std::io::Result<()> {
+    loop {
+        terminal.draw(render)?;
+        if !std::io::stdout().is_terminal() || ratatui::crossterm::event::read()?.is_key_press() {
+            break Ok(());
+        }
+    }
+}
+
+fn render(frame: &mut Frame) {
+    frame.render_widget("hello world", frame.area());
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ratatui::{Terminal, backend::TestBackend};
+
+    #[test]
+    fn renders_hello_world() {
+        let mut terminal =
+            Terminal::new(TestBackend::new(15, 1)).expect("test backend initialization");
+        terminal.draw(render).expect("render frame");
+        terminal.backend().assert_buffer_lines(["hello world    "]);
+    }
+}

info.toml

@@ -11,12 +11,15 @@ final_message = """
 You finished Ratlings! 🎉
 """
 
-exercises = []
-
 # Add exercise metadata here. See CONTRIBUTING.md and the Rustlings community
 # exercises guide: https://rustlings.rust-lang.org/community-exercises/
 #
 # [[exercises]]
 # name = "example"
 # dir = "section"
 # hint = "A helpful hint."
+
+[[exercises]]
+name = "intro1"
+dir = "00_intro"
+hint = "Uncomment the line below the TODO-comment."

solutions/00_intro/intro1.rs

@@ -0,0 +1,33 @@
+use ratatui::{DefaultTerminal, Frame};
+use std::io::IsTerminal;
+
+fn main() -> std::io::Result<()> {
+    ratatui::run(app)
+}
+
+fn app(terminal: &mut DefaultTerminal) -> std::io::Result<()> {
+    loop {
+        terminal.draw(render)?;
+        if !std::io::stdout().is_terminal() || ratatui::crossterm::event::read()?.is_key_press() {
+            break Ok(());
+        }
+    }
+}
+
+fn render(frame: &mut Frame) {
+    frame.render_widget("hello world", frame.area());
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ratatui::{Terminal, backend::TestBackend};
+
+    #[test]
+    fn renders_hello_world() {
+        let mut terminal =
+            Terminal::new(TestBackend::new(15, 1)).expect("test backend initialization");
+        terminal.draw(render).expect("render frame");
+        terminal.backend().assert_buffer_lines(["hello world    "]);
+    }
+}