Reform positional argument parsing (#523)

This diff makes positional argument parsing much cleaner, along with
adding a bunch of tests. Just's positional argument parsing is rather,
complex, so hopefully this reform allows it to both be correct and stay
correct.

User-visible changes:

- `just ..` is now accepted, with the same effect as `just ../`

- `just .` is also accepted, with the same effect as `just`

- It is now an error to pass arguments or overrides to subcommands
  that do not accept them, namely `--dump`, `--edit`, `--list`,
  `--show`, and `--summary`. It is also an error to pass arguments to
  `--evaluate`, although `--evaluate` does of course still accept
  overrides.

  (This is a breaking change, but hopefully worth it, as it will allow us
  to add arguments to subcommands which did not previously take
  them, if we so desire.)

- Subcommands which do not accept arguments may now accept a
  single search-directory argument, so `just --list ../` and
  `just --dump foo/` are now accepted, with the former starting the
  search for the justfile to list in the parent directory, and the latter
  starting the search for the justfile to dump in `foo`.

src/assignment_evaluator.rs

@@ -7,6 +7,7 @@ pub(crate) struct AssignmentEvaluator<'a: 'b, 'b> {
   pub(crate) evaluated: BTreeMap<&'a str, (bool, String)>,
   pub(crate) scope: &'b BTreeMap<&'a str, (bool, String)>,
   pub(crate) working_directory: &'b Path,
+  pub(crate) overrides: &'b BTreeMap<String, String>,
 }
 
 impl<'a, 'b> AssignmentEvaluator<'a, 'b> {
@@ -15,10 +16,12 @@ impl<'a, 'b> AssignmentEvaluator<'a, 'b> {
     working_directory: &'b Path,
     dotenv: &'b BTreeMap<String, String>,
     assignments: &BTreeMap<&'a str, Assignment<'a>>,
+    overrides: &BTreeMap<String, String>,
   ) -> RunResult<'a, BTreeMap<&'a str, (bool, String)>> {
     let mut evaluator = AssignmentEvaluator {
       evaluated: empty(),
       scope: &empty(),
+      overrides,
       config,
       assignments,
       working_directory,
@@ -55,7 +58,7 @@ impl<'a, 'b> AssignmentEvaluator<'a, 'b> {
     }
 
     if let Some(assignment) = self.assignments.get(name) {
-      if let Some(value) = self.config.overrides.get(name) {
+      if let Some(value) = self.overrides.get(name) {
         self
           .evaluated
           .insert(name, (assignment.export, value.to_string()));
@@ -159,47 +162,40 @@ impl<'a, 'b> AssignmentEvaluator<'a, 'b> {
 #[cfg(test)]
 mod tests {
   use super::*;
-  use crate::testing::{compile, config};
 
-  #[test]
+  run_error! {
-  fn backtick_code() {
+    name: backtick_code,
-    let justfile = compile("a:\n echo {{`f() { return 100; }; f`}}");
+    src: "
-    let config = config(&["a"]);
+      a:
-    let dir = env::current_dir().unwrap();
+       echo {{`f() { return 100; }; f`}}
-    match justfile.run(&config, &dir).unwrap_err() {
+    ",
-      RuntimeError::Backtick {
+    args: ["a"],
+    error: RuntimeError::Backtick {
       token,
       output_error: OutputError::Code(code),
-      } => {
+    },
+    check: {
       assert_eq!(code, 100);
       assert_eq!(token.lexeme(), "`f() { return 100; }; f`");
     }
-      other => panic!("expected a code run error, but got: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn export_assignment_backtick() {
+    name: export_assignment_backtick,
-    let text = r#"
+    src: r#"
       export exported_variable = "A"
       b = `echo $exported_variable`
 
       recipe:
         echo {{b}}
-"#;
+    "#,
-
+    args: ["--quiet", "recipe"],
-    let justfile = compile(text);
+    error: RuntimeError::Backtick {
-    let config = config(&["--quiet", "recipe"]);
-    let dir = env::current_dir().unwrap();
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      RuntimeError::Backtick {
         token,
         output_error: OutputError::Code(_),
-      } => {
+    },
+    check: {
       assert_eq!(token.lexeme(), "`echo $exported_variable`");
     }
-      other => panic!("expected a backtick code errror, but got: {}", other),
-    }
   }
 }

src/common.rs

@@ -57,9 +57,10 @@ pub(crate) use crate::{
   function_context::FunctionContext, functions::Functions, interrupt_guard::InterruptGuard,
   interrupt_handler::InterruptHandler, item::Item, justfile::Justfile, lexer::Lexer, line::Line,
   list::List, load_error::LoadError, module::Module, name::Name, output_error::OutputError,
-  parameter::Parameter, parser::Parser, platform::Platform, position::Position, recipe::Recipe,
+  parameter::Parameter, parser::Parser, platform::Platform, position::Position,
-  recipe_context::RecipeContext, recipe_resolver::RecipeResolver, runtime_error::RuntimeError,
+  positional::Positional, recipe::Recipe, recipe_context::RecipeContext,
-  search::Search, search_config::SearchConfig, search_error::SearchError, shebang::Shebang,
+  recipe_resolver::RecipeResolver, runtime_error::RuntimeError, search::Search,
+  search_config::SearchConfig, search_error::SearchError, shebang::Shebang,
   show_whitespace::ShowWhitespace, state::State, string_literal::StringLiteral,
   subcommand::Subcommand, table::Table, token::Token, token_kind::TokenKind, use_color::UseColor,
   variables::Variables, verbosity::Verbosity, warning::Warning,

src/config.rs

@@ -7,12 +7,10 @@ pub(crate) const DEFAULT_SHELL: &str = "sh";
 
 #[derive(Debug, PartialEq)]
 pub(crate) struct Config {
-  pub(crate) arguments: Vec<String>,
   pub(crate) color: Color,
   pub(crate) dry_run: bool,
   pub(crate) highlight: bool,
   pub(crate) invocation_directory: PathBuf,
-  pub(crate) overrides: BTreeMap<String, String>,
   pub(crate) quiet: bool,
   pub(crate) search_config: SearchConfig,
   pub(crate) shell: String,
@@ -27,6 +25,9 @@ mod cmd {
   pub(crate) const LIST: &str = "LIST";
   pub(crate) const SHOW: &str = "SHOW";
   pub(crate) const SUMMARY: &str = "SUMMARY";
+
+  pub(crate) const ALL: &[&str] = &[DUMP, EDIT, LIST, SHOW, SUMMARY, EVALUATE];
+  pub(crate) const ARGLESS: &[&str] = &[DUMP, EDIT, LIST, SHOW, SUMMARY];
 }
 
 mod arg {
@@ -55,11 +56,6 @@ impl Config {
       .version_message("Print version information")
       .setting(AppSettings::ColoredHelp)
       .setting(AppSettings::TrailingVarArg)
-      .arg(
-        Arg::with_name(arg::ARGUMENTS)
-          .multiple(true)
-          .help("The recipe(s) to run, defaults to the first recipe in the justfile"),
-      )
       .arg(
         Arg::with_name(arg::COLOR)
           .long("color")
@@ -129,7 +125,7 @@ impl Config {
           .number_of_values(2)
           .value_names(&["VARIABLE", "VALUE"])
           .multiple(true)
-          .help("Set <VARIABLE> to <VALUE>"),
+          .help("Override <VARIABLE> with <VALUE>"),
       )
       .arg(
         Arg::with_name(arg::SHELL)
@@ -166,15 +162,12 @@ impl Config {
           .help("Use <WORKING-DIRECTORY> as working directory. --justfile must also be set")
           .requires(arg::JUSTFILE),
       )
-      .group(ArgGroup::with_name("EARLY-EXIT").args(&[
+      .arg(
-        arg::ARGUMENTS,
+        Arg::with_name(arg::ARGUMENTS)
-        cmd::DUMP,
+          .multiple(true)
-        cmd::EDIT,
+          .help("Overrides and recipe(s) to run, defaulting to the first recipe in the justfile"),
-        cmd::EVALUATE,
+      )
-        cmd::LIST,
+      .group(ArgGroup::with_name("SUBCOMMAND").args(cmd::ALL));
-        cmd::SHOW,
-        cmd::SUMMARY,
-      ]));
 
     if cfg!(feature = "help4help2man") {
       app.version(env!("CARGO_PKG_VERSION")).about(concat!(
@@ -216,24 +209,6 @@ impl Config {
         .expect("`--color` had no value"),
     )?;
 
-    let subcommand = if matches.is_present(cmd::EDIT) {
-      Subcommand::Edit
-    } else if matches.is_present(cmd::SUMMARY) {
-      Subcommand::Summary
-    } else if matches.is_present(cmd::DUMP) {
-      Subcommand::Dump
-    } else if matches.is_present(cmd::LIST) {
-      Subcommand::List
-    } else if matches.is_present(cmd::EVALUATE) {
-      Subcommand::Evaluate
-    } else if let Some(name) = matches.value_of(cmd::SHOW) {
-      Subcommand::Show {
-        name: name.to_owned(),
-      }
-    } else {
-      Subcommand::Run
-    };
-
     let set_count = matches.occurrences_of(arg::SET);
     let mut overrides = BTreeMap::new();
     if set_count > 0 {
@@ -246,60 +221,17 @@ impl Config {
       }
     }
 
-    fn is_override(arg: &&str) -> bool {
+    let positional = Positional::from_values(matches.values_of(arg::ARGUMENTS));
-      arg.chars().skip(1).any(|c| c == '=')
+
+    for (name, value) in positional.overrides {
+      overrides.insert(name.to_owned(), value.to_owned());
     }
 
-    let raw_arguments: Vec<&str> = matches
-      .values_of(arg::ARGUMENTS)
-      .map(Iterator::collect)
-      .unwrap_or_default();
-
-    for argument in raw_arguments.iter().cloned().take_while(is_override) {
-      let i = argument
-        .char_indices()
-        .skip(1)
-        .find(|&(_, c)| c == '=')
-        .unwrap()
-        .0;
-
-      let name = argument[..i].to_owned();
-      let value = argument[i + 1..].to_owned();
-
-      overrides.insert(name, value);
-    }
-
-    let mut search_directory = None;
-
-    let arguments = raw_arguments
-      .into_iter()
-      .skip_while(is_override)
-      .enumerate()
-      .flat_map(|(i, argument)| {
-        if i == 0 {
-          if let Some(i) = argument.rfind('/') {
-            let (dir, recipe) = argument.split_at(i + 1);
-
-            search_directory = Some(PathBuf::from(dir));
-
-            if recipe.is_empty() {
-              return None;
-            } else {
-              return Some(recipe);
-            }
-          }
-        }
-
-        Some(argument)
-      })
-      .map(|argument| argument.to_owned())
-      .collect::<Vec<String>>();
-
     let search_config = {
       let justfile = matches.value_of(arg::JUSTFILE).map(PathBuf::from);
       let working_directory = matches.value_of(arg::WORKING_DIRECTORY).map(PathBuf::from);
 
-      if let Some(search_directory) = search_directory {
+      if let Some(search_directory) = positional.search_directory.map(PathBuf::from) {
         if justfile.is_some() || working_directory.is_some() {
           return Err(ConfigError::SearchDirConflict);
         }
@@ -323,6 +255,54 @@ impl Config {
       }
     };
 
+    for subcommand in cmd::ARGLESS {
+      if matches.is_present(subcommand) {
+        match (!overrides.is_empty(), !positional.arguments.is_empty()) {
+          (false, false) => {}
+          (true, false) => {
+            return Err(ConfigError::SubcommandOverrides {
+              subcommand: format!("--{}", subcommand.to_lowercase()),
+              overrides,
+            });
+          }
+          (false, true) => {
+            return Err(ConfigError::SubcommandArguments {
+              subcommand: format!("--{}", subcommand.to_lowercase()),
+              arguments: positional.arguments,
+            });
+          }
+          (true, true) => {
+            return Err(ConfigError::SubcommandOverridesAndArguments {
+              subcommand: format!("--{}", subcommand.to_lowercase()),
+              arguments: positional.arguments,
+              overrides,
+            });
+          }
+        }
+      }
+    }
+
+    let subcommand = if matches.is_present(cmd::EDIT) {
+      Subcommand::Edit
+    } else if matches.is_present(cmd::SUMMARY) {
+      Subcommand::Summary
+    } else if matches.is_present(cmd::DUMP) {
+      Subcommand::Dump
+    } else if matches.is_present(cmd::LIST) {
+      Subcommand::List
+    } else if let Some(name) = matches.value_of(cmd::SHOW) {
+      Subcommand::Show {
+        name: name.to_owned(),
+      }
+    } else if matches.is_present(cmd::EVALUATE) {
+      Subcommand::Evaluate { overrides }
+    } else {
+      Subcommand::Run {
+        arguments: positional.arguments,
+        overrides,
+      }
+    };
+
     Ok(Config {
       dry_run: matches.is_present(arg::DRY_RUN),
       highlight: !matches.is_present(arg::NO_HIGHLIGHT),
@@ -333,8 +313,6 @@ impl Config {
       subcommand,
       verbosity,
       color,
-      overrides,
-      arguments,
     })
   }
 
@@ -365,9 +343,15 @@ impl Config {
       }
     }
 
-    match self.subcommand {
+    match &self.subcommand {
       Dump => self.dump(justfile),
-      Run | Evaluate => self.run(justfile, &search.working_directory),
+      Evaluate { overrides } => {
+        self.run(justfile, &search.working_directory, overrides, &Vec::new())
+      }
+      Run {
+        arguments,
+        overrides,
+      } => self.run(justfile, &search.working_directory, overrides, arguments),
       List => self.list(justfile),
       Show { ref name } => self.show(&name, justfile),
       Summary => self.summary(justfile),
@@ -497,12 +481,18 @@ impl Config {
     Ok(())
   }
 
-  fn run(&self, justfile: Justfile, working_directory: &Path) -> Result<(), i32> {
+  fn run(
+    &self,
+    justfile: Justfile,
+    working_directory: &Path,
+    overrides: &BTreeMap<String, String>,
+    arguments: &Vec<String>,
+  ) -> Result<(), i32> {
     if let Err(error) = InterruptHandler::install() {
       warn!("Failed to set CTRL-C handler: {}", error)
     }
 
-    let result = justfile.run(&self, working_directory);
+    let result = justfile.run(&self, working_directory, overrides, arguments);
 
     if !self.quiet {
       result.eprint(self.color)
@@ -582,7 +572,7 @@ OPTIONS:
             Print colorful output [default: auto]  [possible values: auto, always, never]
 
     -f, --justfile <JUSTFILE>                      Use <JUSTFILE> as justfile.
-        --set <VARIABLE> <VALUE>                   Set <VARIABLE> to <VALUE>
+        --set <VARIABLE> <VALUE>                   Override <VARIABLE> with <VALUE>
         --shell <SHELL>                            Invoke <SHELL> to run recipes [default: sh]
     -s, --show <RECIPE>                            Show information about <RECIPE>
     -d, --working-directory <WORKING-DIRECTORY>
@@ -590,7 +580,7 @@ OPTIONS:
 
 
 ARGS:
-    <ARGUMENTS>...    The recipe(s) to run, defaults to the first recipe in the justfile";
+    <ARGUMENTS>...    Overrides and recipe(s) to run, defaulting to the first recipe in the justfile";
 
     let app = Config::app().setting(AppSettings::ColorNever);
     let mut buffer = Vec::new();
@@ -604,11 +594,9 @@ ARGS:
     {
       name: $name:ident,
       args: [$($arg:expr),*],
-      $(arguments: $arguments:expr,)?
       $(color: $color:expr,)?
       $(dry_run: $dry_run:expr,)?
       $(highlight: $highlight:expr,)?
-      $(overrides: $overrides:expr,)?
       $(quiet: $quiet:expr,)?
       $(search_config: $search_config:expr,)?
       $(shell: $shell:expr,)?
@@ -623,14 +611,9 @@ ARGS:
         ];
 
         let want = Config {
-          $(arguments: $arguments.iter().map(|argument| argument.to_string()).collect(),)?
           $(color: $color,)?
           $(dry_run: $dry_run,)?
           $(highlight: $highlight,)?
-          $(
-            overrides: $overrides.iter().cloned()
-              .map(|(key, value): (&str, &str)| (key.to_owned(), value.to_owned())).collect(),
-          )?
           $(quiet: $quiet,)?
           $(search_config: $search_config,)?
           $(shell: $shell.to_string(),)?
@@ -665,17 +648,50 @@ ARGS:
           $($arg,)*
         ];
 
-        error(arguments);
+        let app = Config::app();
+
+        app.get_matches_from_safe(arguments).expect_err("Expected clap error");
+      }
+    };
+    {
+      name: $name:ident,
+      args: [$($arg:expr),*],
+      error: $error:pat,
+      $(check: $check:block,)?
+    } => {
+      #[test]
+      fn $name() {
+        let arguments = &[
+          "just",
+          $($arg,)*
+        ];
+
+        let app = Config::app();
+
+        let matches = app.get_matches_from_safe(arguments).expect("Matching failes");
+
+        match Config::from_matches(&matches).expect_err("config parsing succeeded") {
+          $error => { $($check)? }
+          other => panic!("Unexpected config error: {}", other),
+        }
       }
     }
   }
 
-  fn error(arguments: &[&str]) {
+  macro_rules! map {
-    let app = Config::app();
+    {} => {
-    if let Ok(matches) = app.get_matches_from_safe(arguments) {
+      BTreeMap::new()
-      Config::from_matches(&matches).expect_err("config parsing unexpectedly succeeded");
+    };
-    } else {
+    {
-      return;
+      $($key:literal : $value:literal),* $(,)?
+    } => {
+      {
+        let mut map: BTreeMap<String, String> = BTreeMap::new();
+        $(
+          map.insert($key.to_owned(), $value.to_owned());
+        )*
+        map
+      }
     }
   }
 
@@ -787,31 +803,46 @@ ARGS:
   test! {
     name: set_default,
     args: [],
-    overrides: [],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!(),
+    },
   }
 
   test! {
     name: set_one,
     args: ["--set", "foo", "bar"],
-    overrides: [("foo", "bar")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "bar"},
+    },
   }
 
   test! {
     name: set_empty,
     args: ["--set", "foo", ""],
-    overrides: [("foo", "")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": ""},
+    },
   }
 
   test! {
     name: set_two,
     args: ["--set", "foo", "bar", "--set", "bar", "baz"],
-    overrides: [("foo", "bar"), ("bar", "baz")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "bar", "bar": "baz"},
+    },
   }
 
   test! {
     name: set_override,
     args: ["--set", "foo", "bar", "--set", "foo", "baz"],
-    overrides: [("foo", "baz")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "baz"},
+    },
   }
 
   error! {
@@ -864,7 +895,10 @@ ARGS:
   test! {
     name: subcommand_default,
     args: [],
-    subcommand: Subcommand::Run,
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{},
+    },
   }
 
   test! {
@@ -882,7 +916,9 @@ ARGS:
   test! {
     name: subcommand_evaluate,
     args: ["--evaluate"],
-    subcommand: Subcommand::Evaluate,
+    subcommand: Subcommand::Evaluate {
+      overrides: map!{},
+    },
   }
 
   test! {
@@ -923,31 +959,46 @@ ARGS:
   test! {
     name: arguments,
     args: ["foo", "bar"],
-    arguments: ["foo", "bar"],
+    subcommand: Subcommand::Run {
+      arguments: vec![String::from("foo"), String::from("bar")],
+      overrides: map!{},
+    },
   }
 
   test! {
     name: arguments_leading_equals,
     args: ["=foo"],
-    arguments: ["=foo"],
+    subcommand: Subcommand::Run {
+      arguments: vec!["=foo".to_string()],
+      overrides: map!{},
+    },
   }
 
   test! {
     name: overrides,
     args: ["foo=bar", "bar=baz"],
-    overrides: [("foo", "bar"), ("bar", "baz")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "bar", "bar": "baz"},
+    },
   }
 
   test! {
     name: overrides_empty,
     args: ["foo=", "bar="],
-    overrides: [("foo", ""), ("bar", "")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "", "bar": ""},
+    },
   }
 
   test! {
     name: overrides_override_sets,
     args: ["--set", "foo", "0", "--set", "bar", "1", "foo=bar", "bar=baz"],
-    overrides: [("foo", "bar"), ("bar", "baz")],
+    subcommand: Subcommand::Run {
+      arguments: Vec::new(),
+      overrides: map!{"foo": "bar", "bar": "baz"},
+    },
   }
 
   test! {
@@ -992,10 +1043,10 @@ ARGS:
   test! {
     name: search_directory_parent_with_recipe,
     args: ["../build"],
-    arguments: ["build"],
     search_config: SearchConfig::FromSearchDirectory {
       search_directory: PathBuf::from(".."),
     },
+    subcommand: Subcommand::Run { arguments: vec!["build".to_owned()], overrides: BTreeMap::new() },
   }
 
   test! {
@@ -1017,19 +1068,92 @@ ARGS:
   test! {
     name: search_directory_child_with_recipe,
     args: ["foo/build"],
-    arguments: ["build"],
     search_config: SearchConfig::FromSearchDirectory {
       search_directory: PathBuf::from("foo"),
     },
+    subcommand: Subcommand::Run { arguments: vec!["build".to_owned()], overrides: BTreeMap::new() },
   }
 
   error! {
     name: search_directory_conflict_justfile,
     args: ["--justfile", "bar", "foo/build"],
+    error: ConfigError::SearchDirConflict,
   }
 
   error! {
     name: search_directory_conflict_working_directory,
     args: ["--justfile", "bar", "--working-directory", "baz", "foo/build"],
+    error: ConfigError::SearchDirConflict,
+  }
+
+  error! {
+    name: list_arguments,
+    args: ["--list", "bar"],
+    error: ConfigError::SubcommandArguments { subcommand, arguments },
+    check: {
+      assert_eq!(subcommand, "--list");
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: dump_arguments,
+    args: ["--dump", "bar"],
+    error: ConfigError::SubcommandArguments { subcommand, arguments },
+    check: {
+      assert_eq!(subcommand, "--dump");
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: edit_arguments,
+    args: ["--edit", "bar"],
+    error: ConfigError::SubcommandArguments { subcommand, arguments },
+    check: {
+      assert_eq!(subcommand, "--edit");
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: show_arguments,
+    args: ["--show", "foo", "bar"],
+    error: ConfigError::SubcommandArguments { subcommand, arguments },
+    check: {
+      assert_eq!(subcommand, "--show");
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: summary_arguments,
+    args: ["--summary", "bar"],
+    error: ConfigError::SubcommandArguments { subcommand, arguments },
+    check: {
+      assert_eq!(subcommand, "--summary");
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: subcommand_overrides_and_arguments,
+    args: ["--summary", "bar=baz", "bar"],
+    error: ConfigError::SubcommandOverridesAndArguments { subcommand, arguments, overrides },
+    check: {
+      assert_eq!(subcommand, "--summary");
+      assert_eq!(overrides, map!{"bar": "baz"});
+      assert_eq!(arguments, &["bar"]);
+    },
+  }
+
+  error! {
+    name: summary_overrides,
+    args: ["--summary", "bar=baz"],
+    error: ConfigError::SubcommandOverrides { subcommand, overrides },
+    check: {
+      assert_eq!(subcommand, "--summary");
+      assert_eq!(overrides, map!{"bar": "baz"});
+    },
   }
 }

src/config_error.rs

@@ -17,6 +17,35 @@ pub(crate) enum ConfigError {
     "Path-prefixed recipes may not be used with `--working-directory` or `--justfile`."
   ))]
   SearchDirConflict,
+  #[snafu(display(
+    "`{}` used with unexpected arguments: {}",
+    subcommand,
+    List::and_ticked(arguments)
+  ))]
+  SubcommandArguments {
+    subcommand: String,
+    arguments: Vec<String>,
+  },
+  #[snafu(display(
+      "`{}` used with unexpected overrides: {}; and arguments: {}",
+      subcommand,
+      List::and_ticked(overrides.iter().map(|(key, value)| format!("{}={}", key, value))),
+      List::and_ticked(arguments)))
+  ]
+  SubcommandOverridesAndArguments {
+    subcommand: String,
+    overrides: BTreeMap<String, String>,
+    arguments: Vec<String>,
+  },
+  #[snafu(display(
+      "`{}` used with unexpected overrides: {}",
+      subcommand,
+      List::and_ticked(overrides.iter().map(|(key, value)| format!("{}={}", key, value))),
+  ))]
+  SubcommandOverrides {
+    subcommand: String,
+    overrides: BTreeMap<String, String>,
+  },
 }
 
 impl ConfigError {

src/justfile.rs

@@ -46,13 +46,11 @@ impl<'a> Justfile<'a> {
     &'a self,
     config: &'a Config,
     working_directory: &'a Path,
+    overrides: &'a BTreeMap<String, String>,
+    arguments: &'a Vec<String>,
   ) -> RunResult<'a, ()> {
-    let argvec: Vec<&str> = if !config.arguments.is_empty() {
+    let argvec: Vec<&str> = if !arguments.is_empty() {
-      config
+      arguments.iter().map(|argument| argument.as_str()).collect()
-        .arguments
-        .iter()
-        .map(|argument| argument.as_str())
-        .collect()
     } else if let Some(recipe) = self.first() {
       let min_arguments = recipe.min_arguments();
       if min_arguments > 0 {
@@ -68,8 +66,7 @@ impl<'a> Justfile<'a> {
 
     let arguments = argvec.as_slice();
 
-    let unknown_overrides = config
+    let unknown_overrides = overrides
-      .overrides
       .keys()
       .filter(|name| !self.assignments.contains_key(name.as_str()))
       .map(|name| name.as_str())
@@ -88,9 +85,10 @@ impl<'a> Justfile<'a> {
       working_directory,
       &dotenv,
       &self.assignments,
+      overrides,
     )?;
 
-    if config.subcommand == Subcommand::Evaluate {
+    if let Subcommand::Evaluate { .. } = config.subcommand {
       let mut width = 0;
       for name in scope.keys() {
         width = cmp::max(name.len(), width);
@@ -151,7 +149,7 @@ impl<'a> Justfile<'a> {
 
     let mut ran = empty();
     for (recipe, arguments) in grouped {
-      self.run_recipe(&context, recipe, arguments, &dotenv, &mut ran)?
+      self.run_recipe(&context, recipe, arguments, &dotenv, &mut ran, overrides)?
     }
 
     Ok(())
@@ -178,14 +176,15 @@ impl<'a> Justfile<'a> {
     arguments: &[&'a str],
     dotenv: &BTreeMap<String, String>,
     ran: &mut BTreeSet<&'a str>,
+    overrides: &BTreeMap<String, String>,
   ) -> RunResult<()> {
     for dependency_name in &recipe.dependencies {
       let lexeme = dependency_name.lexeme();
       if !ran.contains(lexeme) {
-        self.run_recipe(context, &self.recipes[lexeme], &[], dotenv, ran)?;
+        self.run_recipe(context, &self.recipes[lexeme], &[], dotenv, ran, overrides)?;
       }
     }
-    recipe.run(context, arguments, dotenv)?;
+    recipe.run(context, arguments, dotenv, overrides)?;
     ran.insert(recipe.name());
     Ok(())
   }
@@ -226,29 +225,23 @@ impl<'a> Display for Justfile<'a> {
 mod tests {
   use super::*;
 
-  use crate::runtime_error::RuntimeError::*;
+  use testing::compile;
-  use crate::testing::{compile, config};
+  use RuntimeError::*;
 
-  #[test]
+  run_error! {
-  fn unknown_recipes() {
+    name: unknown_recipes,
-    let justfile = compile("a:\nb:\nc:");
+    src: "a:\nb:\nc:",
-    let config = config(&["a", "x", "y", "z"]);
+    args: ["a", "x", "y", "z"],
-    let dir = env::current_dir().unwrap();
+    error: UnknownRecipes {
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      UnknownRecipes {
       recipes,
       suggestion,
-      } => {
+    },
+    check: {
       assert_eq!(recipes, &["x", "y", "z"]);
       assert_eq!(suggestion, None);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
-  fn run_shebang() {
   // this test exists to make sure that shebang recipes
   // run correctly. although this script is still
   // executed by a shell its behavior depends on the value of a
@@ -256,86 +249,79 @@ mod tests {
   // whereas in plain recipes variables are not available
   // in subsequent lines and execution stops when a line
   // fails
-    let text = "
+  run_error! {
+    name: run_shebang,
+    src: "
       a:
         #!/usr/bin/env sh
         code=200
           x() { return $code; }
             x
               x
-";
+    ",
-    let justfile = compile(text);
+    args: ["a"],
-    let config = config(&["a"]);
+    error: Code {
-    let dir = env::current_dir().unwrap();
-    match justfile.run(&config, &dir).unwrap_err() {
-      Code {
       recipe,
       line_number,
       code,
-      } => {
+    },
+    check: {
       assert_eq!(recipe, "a");
       assert_eq!(code, 200);
       assert_eq!(line_number, None);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn code_error() {
+    name: code_error,
-    let justfile = compile("fail:\n @exit 100");
+    src: "
-    let config = config(&["fail"]);
+      fail:
-    let dir = env::current_dir().unwrap();
+        @exit 100
-    match justfile.run(&config, &dir).unwrap_err() {
+    ",
-      Code {
+    args: ["fail"],
+    error: Code {
       recipe,
       line_number,
       code,
-      } => {
+    },
+    check: {
       assert_eq!(recipe, "fail");
       assert_eq!(code, 100);
       assert_eq!(line_number, Some(2));
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn run_args() {
+    name: run_args,
-    let text = r#"
+    src: r#"
       a return code:
- @x() { {{return}} {{code + "0"}}; }; x"#;
+        @x() { {{return}} {{code + "0"}}; }; x
-    let justfile = compile(text);
+    "#,
-    let config = config(&["a", "return", "15"]);
+    args: ["a", "return", "15"],
-    let dir = env::current_dir().unwrap();
+    error: Code {
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      Code {
       recipe,
       line_number,
       code,
-      } => {
+    },
+    check: {
       assert_eq!(recipe, "a");
       assert_eq!(code, 150);
-        assert_eq!(line_number, Some(3));
+      assert_eq!(line_number, Some(2));
-      }
-      other => panic!("unexpected error: {}", other),
     }
   }
 
-  #[test]
+  run_error! {
-  fn missing_some_arguments() {
+    name: missing_some_arguments,
-    let justfile = compile("a b c d:");
+    src: "a b c d:",
-    let config = config(&["a", "b", "c"]);
+    args: ["a", "b", "c"],
-    let dir = env::current_dir().unwrap();
+    error: ArgumentCountMismatch {
-    match justfile.run(&config, &dir).unwrap_err() {
-      ArgumentCountMismatch {
       recipe,
       parameters,
       found,
       min,
       max,
-      } => {
+    },
+    check: {
       let param_names = parameters
         .iter()
         .map(|p| p.name.lexeme())
@@ -346,23 +332,20 @@ a return code:
       assert_eq!(min, 3);
       assert_eq!(max, 3);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn missing_some_arguments_variadic() {
+    name: missing_some_arguments_variadic,
-    let justfile = compile("a b c +d:");
+    src: "a b c +d:",
-    let config = config(&["a", "B", "C"]);
+    args: ["a", "B", "C"],
-    let dir = env::current_dir().unwrap();
+    error: ArgumentCountMismatch {
-    match justfile.run(&config, &dir).unwrap_err() {
-      ArgumentCountMismatch {
       recipe,
       parameters,
       found,
       min,
       max,
-      } => {
+    },
+    check: {
       let param_names = parameters
         .iter()
         .map(|p| p.name.lexeme())
@@ -373,24 +356,20 @@ a return code:
       assert_eq!(min, 3);
       assert_eq!(max, usize::MAX - 1);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn missing_all_arguments() {
+    name: missing_all_arguments,
-    let justfile = compile("a b c d:\n echo {{b}}{{c}}{{d}}");
+    src: "a b c d:\n echo {{b}}{{c}}{{d}}",
-    let config = config(&["a"]);
+    args: ["a"],
-    let dir = env::current_dir().unwrap();
+    error: ArgumentCountMismatch {
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      ArgumentCountMismatch {
       recipe,
       parameters,
       found,
       min,
       max,
-      } => {
+    },
+    check: {
       let param_names = parameters
         .iter()
         .map(|p| p.name.lexeme())
@@ -401,24 +380,20 @@ a return code:
       assert_eq!(min, 3);
       assert_eq!(max, 3);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn missing_some_defaults() {
+    name: missing_some_defaults,
-    let justfile = compile("a b c d='hello':");
+    src: "a b c d='hello':",
-    let config = config(&["a", "b"]);
+    args: ["a", "b"],
-    let dir = env::current_dir().unwrap();
+    error: ArgumentCountMismatch {
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      ArgumentCountMismatch {
       recipe,
       parameters,
       found,
       min,
       max,
-      } => {
+    },
+    check: {
       let param_names = parameters
         .iter()
         .map(|p| p.name.lexeme())
@@ -429,24 +404,20 @@ a return code:
       assert_eq!(min, 2);
       assert_eq!(max, 3);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn missing_all_defaults() {
+    name: missing_all_defaults,
-    let justfile = compile("a b c='r' d='h':");
+    src: "a b c='r' d='h':",
-    let config = &config(&["a"]);
+    args: ["a"],
-    let dir = env::current_dir().unwrap();
+    error: ArgumentCountMismatch {
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      ArgumentCountMismatch {
       recipe,
       parameters,
       found,
       min,
       max,
-      } => {
+    },
+    check: {
       let param_names = parameters
         .iter()
         .map(|p| p.name.lexeme())
@@ -457,27 +428,24 @@ a return code:
       assert_eq!(min, 1);
       assert_eq!(max, 3);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn unknown_overrides() {
+    name: unknown_overrides,
-    let config = config(&["foo=bar", "baz=bob", "a"]);
+    src: "
-    let justfile = compile("a:\n echo {{`f() { return 100; }; f`}}");
+      a:
-    let dir = env::current_dir().unwrap();
+       echo {{`f() { return 100; }; f`}}
-
+    ",
-    match justfile.run(&config, &dir).unwrap_err() {
+    args: ["foo=bar", "baz=bob", "a"],
-      UnknownOverrides { overrides } => {
+    error: UnknownOverrides { overrides },
+    check: {
       assert_eq!(overrides, &["baz", "foo"]);
     }
-      other => panic!("unexpected error: {}", other),
-    }
   }
 
-  #[test]
+  run_error! {
-  fn export_failure() {
+    name: export_failure,
-    let text = r#"
+    src: r#"
       export foo = "a"
       baz = "c"
       export bar = "b"
@@ -485,23 +453,16 @@ export abc = foo + bar + baz
 
       wut:
         echo $foo $bar $baz
-"#;
+    "#,
-
+    args: ["--quiet", "wut"],
-    let config = config(&["--quiet", "wut"]);
+    error: Code {
-
-    let justfile = compile(text);
-    let dir = env::current_dir().unwrap();
-
-    match justfile.run(&config, &dir).unwrap_err() {
-      Code {
       code: _,
       line_number,
       recipe,
-      } => {
+    },
+    check: {
       assert_eq!(recipe, "wut");
-        assert_eq!(line_number, Some(8));
+      assert_eq!(line_number, Some(7));
-      }
-      other => panic!("unexpected error: {}", other),
     }
   }
 

src/lexer.rs

@@ -210,6 +210,46 @@ impl<'a> Lexer<'a> {
     }
   }
 
+  /// True if `text` could be an identifier
+  pub(crate) fn is_identifier(text: &str) -> bool {
+    if !text
+      .chars()
+      .next()
+      .map(|c| Self::is_identifier_start(c))
+      .unwrap_or(false)
+    {
+      return false;
+    }
+
+    for c in text.chars().skip(1) {
+      if !Self::is_identifier_continue(c) {
+        return false;
+      }
+    }
+
+    true
+  }
+
+  /// True if `c` can be the first character of an identifier
+  fn is_identifier_start(c: char) -> bool {
+    match c {
+      'a'..='z' | 'A'..='Z' | '_' => true,
+      _ => false,
+    }
+  }
+
+  /// True if `c` can be a continuation character of an idenitifier
+  fn is_identifier_continue(c: char) -> bool {
+    if Self::is_identifier_start(c) {
+      return true;
+    }
+
+    match c {
+      '0'..='9' | '-' => true,
+      _ => false,
+    }
+  }
+
   /// Consume the text and produce a series of tokens
   fn tokenize(mut self) -> CompilationResult<'a, Vec<Token<'a>>> {
     loop {
@@ -362,13 +402,16 @@ impl<'a> Lexer<'a> {
       ' ' | '\t' => self.lex_whitespace(),
       '\'' => self.lex_raw_string(),
       '"' => self.lex_cooked_string(),
-      'a'..='z' | 'A'..='Z' | '_' => self.lex_identifier(),
       _ => {
+        if Self::is_identifier_start(start) {
+          self.lex_identifier()
+        } else {
           self.advance()?;
           Err(self.error(UnknownStartOfToken))
         }
       }
     }
+  }
 
   /// Lex token beginning with `start` in interpolation state
   fn lex_interpolation(
@@ -515,13 +558,16 @@ impl<'a> Lexer<'a> {
     self.lex_double(Eol)
   }
 
-  /// Lex identifier: [a-zA-Z_][a-zA-Z0-9_]*
+  /// Lex name: [a-zA-Z_][a-zA-Z0-9_]*
   fn lex_identifier(&mut self) -> CompilationResult<'a, ()> {
-    while self
+    // advance over initial character
-      .next
+    self.advance()?;
-      .map(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
+
-      .unwrap_or(false)
+    while let Some(c) = self.next {
-    {
+      if !Self::is_identifier_continue(c) {
+        break;
+      }
+
       self.advance()?;
     }
 
@@ -1667,6 +1713,26 @@ mod tests {
     kind:   UnknownStartOfToken,
   }
 
+  error! {
+    name:   invalid_name_start_dash,
+    input:  "-foo",
+    offset: 0,
+    line:   0,
+    column: 0,
+    width:  1,
+    kind:   UnknownStartOfToken,
+  }
+
+  error! {
+    name:   invalid_name_start_digit,
+    input:  "0foo",
+    offset: 0,
+    line:   0,
+    column: 0,
+    width:  1,
+    kind:   UnknownStartOfToken,
+  }
+
   error! {
     name:   unterminated_string,
     input:  r#"a = ""#,

src/lib.rs

@@ -62,6 +62,7 @@ mod parser;
 mod platform;
 mod platform_interface;
 mod position;
+mod positional;
 mod range_ext;
 mod recipe;
 mod recipe_context;

src/positional.rs

@@ -0,0 +1,231 @@
+use crate::common::*;
+
+/// A struct containing the parsed representation of positional
+/// command-line arguments, i.e. arguments that are not flags,
+/// options, or the subcommand.
+///
+/// The DSL of positional arguments is fairly complex and mostly
+/// accidental. There are three possible components: overrides,
+/// a search directory, and the rest:
+///
+/// - Overrides are of the form `NAME=.*`
+///
+/// - After overrides comes a single optional search_directory argument.
+///   This is either '.', '..', or an argument that contains a `/`.
+///
+///   If the argument contains a `/`, everything before and including
+///   the slash is the search directory, and everything after is added
+///   to the rest.
+///
+/// - Everything else is an argument.
+///
+/// Overrides set the values of top-level variables in the justfile
+/// being invoked and are a convenient way to override settings.
+///
+/// For modes that do not take other arguments, the search directory
+/// argument determines where to begin searching for the justfile. This
+/// allows command lines like `just -l ..` and `just ../build` to find
+/// the same justfile.
+///
+/// For modes that do take other arguments, the search argument is simply
+/// prepended to rest.
+#[cfg_attr(test, derive(PartialEq, Debug))]
+pub struct Positional {
+  /// Overrides from values of the form `[a-zA-Z_][a-zA-Z0-9_-]*=.*`
+  pub overrides: Vec<(String, String)>,
+  /// An argument equal to '.', '..', or ending with `/`
+  pub search_directory: Option<String>,
+  /// Everything else
+  pub arguments: Vec<String>,
+}
+
+impl Positional {
+  pub fn from_values<'values>(
+    values: Option<impl IntoIterator<Item = &'values str>>,
+  ) -> Positional {
+    let mut overrides = Vec::new();
+    let mut search_directory = None;
+    let mut arguments = Vec::new();
+
+    if let Some(values) = values {
+      for value in values {
+        if search_directory.is_none() && arguments.is_empty() {
+          if let Some(o) = Self::override_from_value(value) {
+            overrides.push(o);
+          } else if value == "." || value == ".." {
+            search_directory = Some(value.to_owned());
+          } else if let Some(i) = value.rfind('/') {
+            let (dir, tail) = value.split_at(i + 1);
+
+            search_directory = Some(dir.to_owned());
+
+            if !tail.is_empty() {
+              arguments.push(tail.to_owned());
+            }
+          } else {
+            arguments.push(value.to_owned());
+          }
+        } else {
+          arguments.push(value.to_owned());
+        }
+      }
+    }
+
+    Positional {
+      overrides,
+      search_directory,
+      arguments,
+    }
+  }
+
+  /// Parse an override from a value of the form `NAME=.*`.
+  fn override_from_value(value: &str) -> Option<(String, String)> {
+    if let Some(equals) = value.find('=') {
+      let (identifier, equals_value) = value.split_at(equals);
+
+      // exclude `=` from value
+      let value = &equals_value[1..];
+
+      if Lexer::is_identifier(identifier) {
+        Some((identifier.to_owned(), value.to_owned()))
+      } else {
+        None
+      }
+    } else {
+      None
+    }
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  use pretty_assertions::assert_eq;
+
+  macro_rules! test {
+    {
+      name: $name:ident,
+      values: $vals:expr,
+      overrides: $overrides:expr,
+      search_directory: $search_directory:expr,
+      arguments: $arguments:expr,
+    } => {
+      #[test]
+      fn $name() {
+        assert_eq! (
+          Positional::from_values(Some($vals.iter().cloned())),
+          Positional {
+            overrides: $overrides.iter().cloned().map(|(key, value): (&str, &str)| (key.to_owned(), value.to_owned())).collect(),
+            search_directory: $search_directory.map(|dir: &str| dir.to_owned()),
+            arguments: $arguments.iter().cloned().map(|arg: &str| arg.to_owned()).collect(),
+          },
+        )
+      }
+    }
+  }
+
+  test! {
+    name: no_values,
+    values: [],
+    overrides: [],
+    search_directory: None,
+    arguments: [],
+  }
+
+  test! {
+    name: arguments_only,
+    values: ["foo", "bar"],
+    overrides: [],
+    search_directory: None,
+    arguments: ["foo", "bar"],
+  }
+
+  test! {
+    name: all_overrides,
+    values: ["foo=bar", "bar=foo"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: None,
+    arguments: [],
+  }
+
+  test! {
+    name: override_not_name,
+    values: ["foo=bar", "bar.=foo"],
+    overrides: [("foo", "bar")],
+    search_directory: None,
+    arguments: ["bar.=foo"],
+  }
+
+  test! {
+    name: no_overrides,
+    values: ["the-dir/", "baz", "bzzd"],
+    overrides: [],
+    search_directory: Some("the-dir/"),
+    arguments: ["baz", "bzzd"],
+  }
+
+  test! {
+    name: no_search_directory,
+    values: ["foo=bar", "bar=foo", "baz", "bzzd"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: None,
+    arguments: ["baz", "bzzd"],
+  }
+
+  test! {
+    name: no_arguments,
+    values: ["foo=bar", "bar=foo", "the-dir/"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: Some("the-dir/"),
+    arguments: [],
+  }
+
+  test! {
+    name: all_dot,
+    values: ["foo=bar", "bar=foo", ".", "garnor"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: Some("."),
+    arguments: ["garnor"],
+  }
+
+  test! {
+    name: all_dot_dot,
+    values: ["foo=bar", "bar=foo", "..", "garnor"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: Some(".."),
+    arguments: ["garnor"],
+  }
+
+  test! {
+    name: all_slash,
+    values: ["foo=bar", "bar=foo", "/", "garnor"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: Some("/"),
+    arguments: ["garnor"],
+  }
+
+  test! {
+    name: search_directory_after_argument,
+    values: ["foo=bar", "bar=foo", "baz", "bzzd", "bar/"],
+    overrides: [("foo", "bar"), ("bar", "foo")],
+    search_directory: None,
+    arguments: ["baz", "bzzd", "bar/"],
+  }
+
+  test! {
+    name: override_after_search_directory,
+    values: ["..", "a=b"],
+    overrides: [],
+    search_directory: Some(".."),
+    arguments: ["a=b"],
+  }
+
+  test! {
+    name: override_after_argument,
+    values: ["a", "a=b"],
+    overrides: [],
+    search_directory: None,
+    arguments: ["a", "a=b"],
+  }
+}

src/recipe.rs

@@ -69,6 +69,7 @@ impl<'a> Recipe<'a> {
     context: &RecipeContext<'a>,
     arguments: &[&'a str],
     dotenv: &BTreeMap<String, String>,
+    overrides: &BTreeMap<String, String>,
   ) -> RunResult<'a, ()> {
     let config = &context.config;
 
@@ -89,6 +90,7 @@ impl<'a> Recipe<'a> {
       evaluated: empty(),
       working_directory: context.working_directory,
       scope: &context.scope,
+      overrides,
       config,
       dotenv,
     };

src/search.rs

@@ -25,7 +25,14 @@ impl Search {
       }
 
       SearchConfig::FromSearchDirectory { search_directory } => {
-        let justfile = Self::justfile(search_directory)?;
+        let search_directory =
+          search_directory
+            .canonicalize()
+            .context(search_error::Canonicalize {
+              path: search_directory,
+            })?;
+
+        let justfile = Self::justfile(&search_directory)?;
 
         let working_directory = Self::working_directory_from_justfile(&justfile)?;
 
@@ -58,6 +65,7 @@ impl Search {
 
   fn justfile(directory: &Path) -> SearchResult<PathBuf> {
     let mut candidates = Vec::new();
+
     let entries = fs::read_dir(directory).map_err(|io_error| SearchError::Io {
       io_error,
       directory: directory.to_owned(),

src/subcommand.rs

@@ -1,10 +1,19 @@
+use crate::common::*;
+
 #[derive(PartialEq, Clone, Debug)]
 pub(crate) enum Subcommand {
   Dump,
   Edit,
-  Evaluate,
+  Evaluate {
-  Run,
+    overrides: BTreeMap<String, String>,
+  },
+  Run {
+    overrides: BTreeMap<String, String>,
+    arguments: Vec<String>,
+  },
   List,
-  Show { name: String },
+  Show {
+    name: String,
+  },
   Summary,
 }

src/testing.rs

@@ -32,12 +32,12 @@ macro_rules! analysis_error {
     ) => {
     #[test]
     fn $name() {
-      $crate::testing::error($input, $offset, $line, $column, $width, $kind);
+      $crate::testing::analysis_error($input, $offset, $line, $column, $width, $kind);
     }
   };
 }
 
-pub(crate) fn error(
+pub(crate) fn analysis_error(
   src: &str,
   offset: usize,
   line: usize,
@@ -66,27 +66,36 @@ pub(crate) fn error(
   }
 }
 
+macro_rules! run_error {
+  {
+    name: $name:ident,
+    src:  $src:expr,
+    args: $args:expr,
+    error: $error:pat,
+    check: $check:block $(,)?
+  } => {
     #[test]
-fn readme_test() {
+    fn $name() {
-  let mut justfiles = vec![];
+      let config = &$crate::testing::config(&$args);
-  let mut current = None;
+      let current_dir = std::env::current_dir().unwrap();
 
-  for line in fs::read_to_string("README.adoc").unwrap().lines() {
+      if let Subcommand::Run{ overrides, arguments } = &config.subcommand {
-    if let Some(mut justfile) = current {
+        match $crate::compiler::Compiler::compile(&$crate::testing::unindent($src))
-      if line == "```" {
+          .expect("Expected successful compilation")
-        justfiles.push(justfile);
+          .run(
-        current = None;
+            config,
+            &current_dir,
+            &overrides,
+            &arguments,
+          ).expect_err("Expected runtime error") {
+            $error => $check
+            other => {
+              panic!("Unexpected run error: {:?}", other);
+            }
+          }
       } else {
-        justfile += line;
+          panic!("Unexpected subcommand: {:?}", config.subcommand);
-        justfile += "\n";
-        current = Some(justfile);
-      }
-    } else if line == "```make" {
-      current = Some(String::new());
       }
     }
-
+  };
-  for justfile in justfiles {
-    compile(&justfile);
-  }
 }

test-utilities/src/lib.rs

@@ -7,13 +7,16 @@ pub fn tempdir() -> tempfile::TempDir {
     .expect("failed to create temporary directory")
 }
 
-pub fn assert_stdout(output: &Output, stdout: &str) {
+pub fn assert_success(output: &Output) {
   if !output.status.success() {
     eprintln!("stderr: {}", String::from_utf8_lossy(&output.stderr));
     eprintln!("stdout: {}", String::from_utf8_lossy(&output.stdout));
     panic!(output.status);
   }
+}
 
+pub fn assert_stdout(output: &Output, stdout: &str) {
+  assert_success(output);
   assert_eq!(String::from_utf8_lossy(&output.stdout), stdout);
 }
 

tests/readme.rs

@@ -0,0 +1,41 @@
+use std::{fs, process::Command};
+
+use executable_path::executable_path;
+use test_utilities::{assert_success, tempdir};
+
+#[test]
+fn readme() {
+  let mut justfiles = vec![];
+  let mut current = None;
+
+  for line in fs::read_to_string("README.adoc").unwrap().lines() {
+    if let Some(mut justfile) = current {
+      if line == "```" {
+        justfiles.push(justfile);
+        current = None;
+      } else {
+        justfile += line;
+        justfile += "\n";
+        current = Some(justfile);
+      }
+    } else if line == "```make" {
+      current = Some(String::new());
+    }
+  }
+
+  for justfile in justfiles {
+    let tmp = tempdir();
+
+    let path = tmp.path().join("justfile");
+
+    fs::write(&path, &justfile).unwrap();
+
+    let output = Command::new(executable_path("just"))
+      .current_dir(tmp.path())
+      .arg("--dump")
+      .output()
+      .unwrap();
+
+    assert_success(&output);
+  }
+}

tests/search.rs

@@ -121,3 +121,27 @@ fn test_downwards_multiple_path_argument() {
   search_test(&path, &["./a/b/"]);
   search_test(&path, &["./a/b/default"]);
 }
+
+#[test]
+fn single_downards() {
+  let tmp = tmptree! {
+    justfile: "default:\n\techo ok",
+    child: {},
+  };
+
+  let path = tmp.path();
+
+  search_test(&path, &["child/"]);
+}
+
+#[test]
+fn single_upwards() {
+  let tmp = tmptree! {
+    justfile: "default:\n\techo ok",
+    child: {},
+  };
+
+  let path = tmp.path().join("child");
+
+  search_test(&path, &["../"]);
+}