Allow --justfile without --working-directory

src/run.rs

@@ -106,8 +106,7 @@ pub fn run() {
         .short("f")
         .long("justfile")
         .takes_value(true)
-        .help("Use <JUSTFILE> as justfile. --working-directory must also be set")
-        .requires("WORKING-DIRECTORY"),
+        .help("Use <JUSTFILE> as justfile."),
     )
     .arg(
       Arg::with_name("LIST")
@@ -243,22 +242,45 @@ pub fn run() {
     })
     .collect::<Vec<&str>>();
 
-  let justfile_option = matches.value_of("JUSTFILE");
-  let working_directory_option = matches.value_of("WORKING-DIRECTORY");
+  let justfile = matches.value_of("JUSTFILE").map(Path::new);
+  let mut working_directory = matches.value_of("WORKING-DIRECTORY").map(PathBuf::from);
+
+  if let (Some(justfile), None) = (justfile, working_directory.as_ref()) {
+    let mut justfile = justfile.to_path_buf();
+
+    if !justfile.is_absolute() {
+      match justfile.canonicalize() {
+        Ok(canonical) => justfile = canonical,
+        Err(err) => die!(
+          "Could not canonicalize justfile path `{}`: {}",
+          justfile.display(),
+          err
+        ),
+      }
+    }
+
+    justfile.pop();
+
+    working_directory = Some(justfile);
+  }
 
   let text;
-  if let (Some(file), Some(directory)) = (justfile_option, working_directory_option) {
+  if let (Some(justfile), Some(directory)) = (justfile, working_directory) {
     if matches.is_present("EDIT") {
-      edit(file);
+      edit(justfile);
     }
 
-    text = fs::File::open(file)
+    text = fs::File::open(justfile)
       .unwrap_or_else(|error| die!("Error opening justfile: {}", error))
       .slurp()
       .unwrap_or_else(|error| die!("Error reading justfile: {}", error));
 
-    if let Err(error) = env::set_current_dir(directory) {
-      die!("Error changing directory to {}: {}", directory, error);
+    if let Err(error) = env::set_current_dir(&directory) {
+      die!(
+        "Error changing directory to {}: {}",
+        directory.display(),
+        error
+      );
     }
   } else {
     let name;

tests/working_directory.rs

@@ -0,0 +1,35 @@
+extern crate executable_path;
+extern crate tempdir;
+
+use executable_path::executable_path;
+use std::{error::Error, fs, process::Command};
+use tempdir::TempDir;
+
+/// Test that just runs with the correct working directory when invoked with
+/// `--justfile` but not `--working-directory`
+#[test]
+fn justfile_without_working_directory() -> Result<(), Box<Error>> {
+  let tmp = TempDir::new("just-integration")?;
+  let justfile = tmp.path().join("justfile");
+  let data = tmp.path().join("data");
+  fs::write(
+    &justfile,
+    "foo = `cat data`\ndefault:\n echo {{foo}}\n cat data",
+  )?;
+  fs::write(&data, "found it")?;
+
+  let output = Command::new(executable_path("just"))
+    .arg("--justfile")
+    .arg(&justfile)
+    .output()?;
+
+  if !output.status.success() {
+    panic!()
+  }
+
+  let stdout = String::from_utf8(output.stdout).unwrap();
+
+  assert_eq!(stdout, "found it\nfound it");
+
+  Ok(())
+}