CLI --export-svg Error Handling with pico-args

We resolved two issues when running turtle programs with `--export-svg`: 1. **Missing filename**: Previously, running `--export-svg` without a filename caused the CLI parser to ignore the flag and open the GUI window. Now, it emits `Error: --export-svg: option requires an argument` and terminates with exit code 1. 2. **Missing `svg` feature**: Previously, running `--export-svg` without the `svg` feature enabled ignored the flag if no filename was passed and opened the window. Now, any invocation of `--export-svg` without `--features svg` emits `Error: SVG export feature is not enabled. Please rebuild with --features svg` and terminates with exit code 1. --- - Added [`pico-args = { version = "0.5", features = ["eq-separator"] }`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/Cargo.toml) under `[dependencies]`. - In [`turtle-lib/src/export.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/export.rs): - Added `MissingFeature(String)` to `ExportError` for clean error display. - Implemented `parse_svg_export_from_args(args: &mut pico_args::Arguments) -> Result<Option<String>, pico_args::Error>` to parse `--export-svg <file>` and `--export-svg=<file>`, treating empty or flag arguments as missing values (`OptionWithoutAValue`). - Updated `parse_svg_export_arg() -> Option<String>` for backward compatibility. - In `handle_svg_export`: - Under `#[cfg(not(feature = "svg"))]`: detects any presence of `--export-svg`, outputs `Error: SVG export feature is not enabled. Please rebuild with --features svg`, and exits with code 1. - Under `#[cfg(feature = "svg")]`: handles missing arguments with `Error: --export-svg: option requires an argument` (exit 1), valid exports (exit 0), and leaves unknown arguments untouched so Macroquad or user flags continue to work. - Added unit tests covering all flag parsing variants and error displays. - In [`turtle-lib-macros/src/lib.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib-macros/src/lib.rs): - Simplified the macro expansion in `turtle_main` to delegate directly to `turtle_lib::export::handle_svg_export(&mut build_commands);`. - Updated documentation comments to match. --- ```bash cargo test --package turtle-lib cargo test --package turtle-lib --features svg cargo test --package turtle-lib-macros cargo clippy --package turtle-lib -- -Wclippy::pedantic -Aclippy::cast_precision_loss -Aclippy::cast_sign_loss -Aclippy::cast_possible_truncation cargo clippy --package turtle-lib --features svg -- -Wclippy::pedantic -Aclippy::cast_precision_loss -Aclippy::cast_sign_loss -Aclippy::cast_possible_truncation cargo clippy --package turtle-lib-macros -- -Wclippy::pedantic ``` - **Unit tests**: All 29 unit tests in `turtle-lib` and 18 unit tests in `turtle-lib-macros` passed. - **Doctests**: All 34 doctests passed. - **Clippy**: Passed with zero warnings across all crates and feature configurations. | Scenario | Command | Result | Exit Code | Window Opened? | |---|---|---|---|---| | Missing feature, missing filename | `cargo run --example hello_turtle -- --export-svg` | `Error: SVG export feature is not enabled. Please rebuild with --features svg` | 1 | No | | Missing feature, with filename | `cargo run --example hello_turtle -- --export-svg test.svg` | `Error: SVG export feature is not enabled. Please rebuild with --features svg` | 1 | No | | Feature enabled, missing filename | `cargo run --example hello_turtle --features svg -- --export-svg` | `Error: --export-svg: option requires an argument` | 1 | No | | Feature enabled, with filename | `cargo run --example hello_turtle --features svg -- --export-svg /tmp/pico_test.svg` | `SVG exported successfully to: /tmp/pico_test.svg` | 0 | No | | Feature enabled, equals syntax | `cargo run --example hello_turtle --features svg -- --export-svg=/tmp/pico_test_eq.svg` | `SVG exported successfully to: /tmp/pico_test_eq.svg` | 0 | No | | Feature enabled, extra flags | `cargo run --example hello_turtle --features svg -- --export-svg /tmp/pico_test_extra.svg --custom-flag` | `SVG exported successfully to: /tmp/pico_test_extra.svg` | 0 | No | | Normal run (no flag) | `cargo run --example hello_turtle` | Interactive window opens normally | 0 | Yes |
2026-09-20 12:36:15 +02:00
parent d855750970
commit b19919f8b7
3 changed files with 137 additions and 41 deletions
@@ -66,17 +66,11 @@ use syn::ItemFn;
 /// use turtle_lib::*;
 ///
 /// fn main() {
-///     // Handle optional SVG export headlessly without opening a window
-///     if let Some(filename) = turtle_lib::export::parse_svg_export_arg() {
 ///     let mut build_commands = |turtle: &mut turtle_lib::TurtlePlan| {
 ///         my_drawing(turtle);
 ///     };
-///         if let Err(e) = turtle_lib::export::run_headless_svg_export(&mut build_commands, &filename) {
-///             eprintln!("Error exporting SVG: {:?}", e);
-///             std::process::exit(1);
-///         }
-///         return;
-///     }
+///     // Handle optional SVG export headlessly without opening a window
+///     turtle_lib::export::handle_svg_export(&mut build_commands);
 ///
 ///     // Normal interactive GUI mode with window
 ///     turtle_lib::macroquad::Window::new("My Turtle Drawing", async {
@@ -252,18 +246,7 @@ fn turtle_main_impl(
            };

            // If --export-svg flag is present, export headlessly without opening a window
-            if let Some(filename) = turtle_lib::export::parse_svg_export_arg() {
-                match turtle_lib::export::run_headless_svg_export(&mut build_commands, &filename) {
-                    Ok(()) => {
-                        println!("SVG exported successfully to: {}", filename);
-                        return;
-                    }
-                    Err(e) => {
-                        eprintln!("Error exporting SVG: {}", e);
-                        std::process::exit(1);
-                    }
-                }
-            }
+            turtle_lib::export::handle_svg_export(&mut build_commands);

            // Normal rendering mode (interactive window)
            turtle_lib::macroquad::Window::new(#window_title, async {
@@ -14,6 +14,7 @@ tracing = { version = "0.1", features = [
 ], default-features = false }
 turtle-lib-macros = { path = "../turtle-lib-macros" }
 crossbeam = "0.8"
+pico-args = { version = "0.5", features = ["eq-separator"] }

 [dev-dependencies]
 # For examples and testing
@@ -8,6 +8,7 @@ pub enum ExportError {
    Io(std::io::Error),
    Format(String),
    Execution(String),
+    MissingFeature(String),
    // Additional formats can be added here.
 }

@@ -17,6 +18,7 @@ impl std::fmt::Display for ExportError {
            Self::Io(err) => write!(f, "I/O error: {err}"),
            Self::Format(msg) => write!(f, "format error: {msg}"),
            Self::Execution(msg) => write!(f, "execution error: {msg}"),
+            Self::MissingFeature(msg) => write!(f, "{msg}"),
        }
    }
 }
@@ -25,7 +27,7 @@ impl std::error::Error for ExportError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::Io(err) => Some(err),
-            Self::Format(_) | Self::Execution(_) => None,
+            Self::Format(_) | Self::Execution(_) | Self::MissingFeature(_) => None,
        }
    }
 }
@@ -47,18 +49,27 @@ pub(crate) trait DrawingExporter {
    fn export(&self, world: &TurtleWorld, filename: &str) -> Result<(), ExportError>;
 }

+/// Parse the `--export-svg` parameter from a `pico_args::Arguments` instance.
+///
+/// # Errors
+///
+/// Returns `pico_args::Error` if `--export-svg` is provided without a valid filename.
+pub fn parse_svg_export_from_args(
+    args: &mut pico_args::Arguments,
+) -> Result<Option<String>, pico_args::Error> {
+    match args.opt_value_from_str::<_, String>("--export-svg") {
+        Ok(Some(s)) if s.trim().is_empty() || s.starts_with('-') => {
+            Err(pico_args::Error::OptionWithoutAValue("--export-svg"))
+        }
+        other => other,
+    }
+}
+
 /// Check command-line arguments for the `--export-svg <filename>` flag.
 #[must_use]
 pub fn parse_svg_export_arg() -> Option<String> {
-    let args: Vec<String> = std::env::args().collect();
-    let mut i = 1;
-    while i < args.len() {
-        if args[i] == "--export-svg" && i + 1 < args.len() {
-            return Some(args[i + 1].clone());
-        }
-        i += 1;
-    }
-    None
+    let mut args = pico_args::Arguments::from_env();
+    parse_svg_export_from_args(&mut args).ok().flatten()
 }

 #[cfg(feature = "svg")]
@@ -166,7 +177,7 @@ where
    {
        let _ = &mut build_commands;
        let _ = filename;
-        Err(ExportError::Format(
+        Err(ExportError::MissingFeature(
            "SVG export feature is not enabled. Please rebuild with --features svg".to_string(),
        ))
    }
@@ -179,16 +190,117 @@ pub fn handle_svg_export<F>(build_commands: F)
 where
    F: FnMut(&mut TurtlePlan),
 {
-    if let Some(filename) = parse_svg_export_arg() {
+    let mut args = pico_args::Arguments::from_env();
+    let export_arg = parse_svg_export_from_args(&mut args);
+
+    #[cfg(not(feature = "svg"))]
+    {
+        let _ = build_commands;
+        if export_arg.is_err() || matches!(export_arg, Ok(Some(_))) {
+            eprintln!("Error: SVG export feature is not enabled. Please rebuild with --features svg");
+            std::process::exit(1);
+        }
+    }
+
+    #[cfg(feature = "svg")]
+    {
+        match export_arg {
+            Ok(None) => {}
+            Err(_) => {
+                eprintln!("Error: --export-svg: option requires an argument");
+                std::process::exit(1);
+            }
+            Ok(Some(filename)) => {
                match run_headless_svg_export(build_commands, &filename) {
                    Ok(()) => {
                        println!("SVG exported successfully to: {filename}");
                        std::process::exit(0);
                    }
                    Err(e) => {
-                eprintln!("Error exporting SVG: {e}");
+                        eprintln!("Error: {e}");
                        std::process::exit(1);
                    }
                }
            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::ffi::OsString;
+
+    fn make_args(args: &[&str]) -> pico_args::Arguments {
+        let os_args: Vec<OsString> = args.iter().map(OsString::from).collect();
+        pico_args::Arguments::from_vec(os_args)
+    }
+
+    #[test]
+    fn test_parse_svg_export_with_filename() {
+        let mut args = make_args(&["--export-svg", "output.svg"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert_eq!(res.unwrap(), Some("output.svg".to_string()));
+    }
+
+    #[test]
+    fn test_parse_svg_export_with_equals() {
+        let mut args = make_args(&["--export-svg=output.svg"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert_eq!(res.unwrap(), Some("output.svg".to_string()));
+    }
+
+    #[test]
+    fn test_parse_svg_export_missing_argument_at_end() {
+        let mut args = make_args(&["--export-svg"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert!(matches!(res, Err(pico_args::Error::OptionWithoutAValue(_))));
+    }
+
+    #[test]
+    fn test_parse_svg_export_missing_argument_followed_by_flag() {
+        let mut args = make_args(&["--export-svg", "--verbose"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert!(matches!(res, Err(pico_args::Error::OptionWithoutAValue(_))));
+    }
+
+    #[test]
+    fn test_parse_svg_export_empty_string() {
+        let mut args = make_args(&["--export-svg", ""]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert!(matches!(res, Err(pico_args::Error::OptionWithoutAValue(_))));
+    }
+
+    #[test]
+    fn test_parse_svg_export_empty_equals() {
+        let mut args = make_args(&["--export-svg="]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert!(matches!(res, Err(pico_args::Error::OptionWithoutAValue(_))));
+    }
+
+    #[test]
+    fn test_parse_svg_export_not_present() {
+        let mut args = make_args(&["--verbose", "input.txt"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert_eq!(res.unwrap(), None);
+    }
+
+    #[test]
+    fn test_parse_svg_export_preserves_unknown_args() {
+        let mut args = make_args(&["--other-flag", "--export-svg", "out.svg", "positional"]);
+        let res = parse_svg_export_from_args(&mut args);
+        assert_eq!(res.unwrap(), Some("out.svg".to_string()));
+        assert!(args.contains("--other-flag"));
+    }
+
+    #[test]
+    fn test_export_error_display_missing_feature() {
+        let err = ExportError::MissingFeature(
+            "SVG export feature is not enabled. Please rebuild with --features svg".to_string(),
+        );
+        assert_eq!(
+            err.to_string(),
+            "SVG export feature is not enabled. Please rebuild with --features svg"
+        );
+    }
 }