Add --features etc

NEWS.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- New: `--features`, `--no-default-features` and `--all-features` options are passed through to Cargo.
+
 ## 24.2.0
 
 - New: Colored output can be enabled in CI or other noninteractive situations by passing `--colors=always`, or setting `CARGO_TERM_COLOR=always`, or `CLICOLOR_FORCE=1`. Colors can similarly be forced off with `--colors=never`, `CARGO_TERM_COLOR=never`, or `NO_COLOR=1`.

book/src/cargo-args.md

@@ -7,6 +7,16 @@ test`.
 
 There is not yet a way to pass options only to `cargo build` but not to `cargo test`.
 
+## Feature flags
+
+The `--features`, `--all-features`, and `--no-default-features` flags can be given to cargo-mutants and they will be passed down to `cargo build` and `cargo test`.
+
+For example, this can be useful if you have tests that are only enabled with a feature flag:
+
+```shell
+cargo mutants -- --features=fail/failpoints
+```
+
 ## Arguments to all `cargo` commands
 
 To pass more arguments to every Cargo invocation, use `--cargo-arg`, or the `additional_cargo_args` configuration key.

src/cargo.rs

@@ -90,6 +90,19 @@ fn cargo_argv(
     } else {
         cargo_args.push("--workspace".to_string());
     }
+    let features = &options.features;
+    if features.no_default_features {
+        cargo_args.push("--no-default-features".to_owned());
+    }
+    if features.all_features {
+        cargo_args.push("--all-features".to_owned());
+    }
+    cargo_args.extend(
+        features
+            .features
+            .iter()
+            .map(|f| format!("--features={}", f)),
+    );
     cargo_args.extend(options.additional_cargo_args.iter().cloned());
     if phase == Phase::Test {
         cargo_args.extend(options.additional_cargo_test_args.iter().cloned());
@@ -232,4 +245,46 @@ mod test {
             ]
         );
     }
+
+    #[test]
+    fn no_default_features_args_passed_to_cargo() {
+        let args = Args::try_parse_from(["mutants", "--no-default-features"].as_slice()).unwrap();
+        let options = Options::from_args(&args).unwrap();
+        let build_dir = Utf8Path::new("/tmp/buildXYZ");
+        assert_eq!(
+            cargo_argv(build_dir, None, Phase::Check, &options)[1..],
+            ["check", "--tests", "--workspace", "--no-default-features"]
+        );
+    }
+
+    #[test]
+    fn all_features_args_passed_to_cargo() {
+        let args = Args::try_parse_from(["mutants", "--all-features"].as_slice()).unwrap();
+        let options = Options::from_args(&args).unwrap();
+        let build_dir = Utf8Path::new("/tmp/buildXYZ");
+        assert_eq!(
+            cargo_argv(build_dir, None, Phase::Check, &options)[1..],
+            ["check", "--tests", "--workspace", "--all-features"]
+        );
+    }
+
+    #[test]
+    fn feature_args_passed_to_cargo() {
+        let args = Args::try_parse_from(
+            ["mutants", "--features", "foo", "--features", "bar,baz"].as_slice(),
+        )
+        .unwrap();
+        let options = Options::from_args(&args).unwrap();
+        let build_dir = Utf8Path::new("/tmp/buildXYZ");
+        assert_eq!(
+            cargo_argv(build_dir, None, Phase::Check, &options)[1..],
+            [
+                "check",
+                "--tests",
+                "--workspace",
+                "--features=foo",
+                "--features=bar,baz"
+            ]
+        );
+    }
 }

src/main.rs

@@ -103,7 +103,7 @@ pub enum BaselineStrategy {
     about,
     after_help = SPONSOR_MESSAGE,
 )]
-struct Args {
+pub struct Args {
     /// show cargo output for all invocations (very verbose).
     #[arg(long, help_heading = "Output")]
     all_logs: bool,
@@ -311,6 +311,28 @@ struct Args {
     /// pass remaining arguments to cargo test after all options and after `--`.
     #[arg(last = true, help_heading = "Execution")]
     cargo_test_args: Vec<String>,
+
+    #[command(flatten)]
+    features: Features,
+}
+
+#[derive(clap::Args, PartialEq, Eq, Debug, Default, Clone)]
+pub struct Features {
+    //---  features
+    /// Space or comma separated list of features to activate.
+    // (The features are not split or parsed, just passed through to Cargo.)
+    #[arg(long, help_heading = "Feature Selection")]
+    pub features: Vec<String>,
+
+    /// Do not activate the `default` feature.
+    #[arg(long, help_heading = "Feature Selection")]
+    pub no_default_features: bool,
+
+    /// Activate all features.
+    // (This does not conflict because this only turns on features in the top level package,
+    // and you might use --features to turn on features in dependencies.)
+    #[arg(long, help_heading = "Feature Selection")]
+    pub all_features: bool,
 }
 
 fn main() -> Result<()> {
@@ -358,6 +380,7 @@ fn main() -> Result<()> {
         config::Config::read_tree_config(&workspace.dir)?
     };
     debug!(?config);
+    debug!(?args.features);
     let options = Options::new(&args, &config)?;
     debug!(?options);
     let package_filter = if !args.mutate_packages.is_empty() {

src/options.rs

@@ -70,6 +70,9 @@ pub struct Options {
     /// Additional arguments to `cargo test`.
     pub additional_cargo_test_args: Vec<String>,
 
+    /// Selection of features for cargo.
+    pub features: super::Features,
+
     /// Files to examine.
     pub examine_globset: Option<GlobSet>,
 
@@ -194,6 +197,7 @@ impl Options {
                 .context("Failed to compile exclude_re regex")?,
             examine_globset: build_glob_set(or_slices(&args.file, &config.examine_globs))?,
             exclude_globset: build_glob_set(or_slices(&args.exclude, &config.exclude_globs))?,
+            features: args.features.clone(),
             gitignore: args.gitignore,
             in_place: args.in_place,
             jobs: args.jobs,
@@ -219,6 +223,11 @@ impl Options {
         });
         Ok(options)
     }
+
+    #[cfg(test)]
+    pub fn from_args(args: &Args) -> Result<Options> {
+        Options::new(args, &Config::default())
+    }
 }
 
 /// If the first slices is non-empty, return that, otherwise the second.
@@ -301,4 +310,61 @@ mod test {
         let options = Options::new(&args, &config).unwrap();
         assert_eq!(options.test_tool, TestTool::Nextest);
     }
+
+    #[test]
+    fn features_arg() {
+        let args = Args::try_parse_from(["mutants", "--features", "nice,shiny features"]).unwrap();
+        assert_eq!(
+            args.features.features.iter().as_ref(),
+            ["nice,shiny features"]
+        );
+        assert!(!args.features.no_default_features);
+        assert!(!args.features.all_features);
+
+        let options = Options::new(&args, &Config::default()).unwrap();
+        assert_eq!(
+            options.features.features.iter().as_ref(),
+            ["nice,shiny features"]
+        );
+        assert!(!options.features.no_default_features);
+        assert!(!options.features.all_features);
+    }
+
+    #[test]
+    fn no_default_features_arg() {
+        let args = Args::try_parse_from([
+            "mutants",
+            "--no-default-features",
+            "--features",
+            "nice,shiny features",
+        ])
+        .unwrap();
+
+        let options = Options::new(&args, &Config::default()).unwrap();
+        assert_eq!(
+            options.features.features.iter().as_ref(),
+            ["nice,shiny features"]
+        );
+        assert!(options.features.no_default_features);
+        assert!(!options.features.all_features);
+    }
+
+    #[test]
+    fn all_features_arg() {
+        let args = Args::try_parse_from([
+            "mutants",
+            "--all-features",
+            "--features",
+            "nice,shiny features",
+        ])
+        .unwrap();
+
+        let options = Options::new(&args, &Config::default()).unwrap();
+        assert_eq!(
+            options.features.features.iter().as_ref(),
+            ["nice,shiny features"]
+        );
+        assert!(!options.features.no_default_features);
+        assert!(options.features.all_features);
+    }
 }