Allow justfile to be named Justfile (#19)

Priority is given to `justfile` to match the behavior of GNU make.

README.md

@@ -5,7 +5,7 @@ just
 
 `just` is a handy way to save and run commands.
 
-Commands are stored in a file called `justfile` with syntax inspired by `make`:
+Commands are stored in a file called `justfile` or `Justfile` with syntax inspired by `make`:
 
 ```make
 test-all: build

src/app.rs

@@ -92,15 +92,21 @@ pub fn app() {
       die!("Error changing directory to {}: {}", directory, error);
     }
   } else {
-    loop {
-      match fs::metadata("justfile") {
-        Ok(metadata) => if metadata.is_file() { break; },
+    let name;
+    'outer: loop {
+      for candidate in &["justfile", "Justfile"] {
+        match fs::metadata(candidate) {
+          Ok(metadata) => if metadata.is_file() {
+            name = *candidate;
+            break 'outer;
+          },
           Err(error) => {
             if error.kind() != io::ErrorKind::NotFound {
               die!("Error fetching justfile metadata: {}", error)
             }
           }
         }
+      }
 
       match env::current_dir() {
         Ok(pathbuf) => if pathbuf.as_os_str() == "/" { die!("No justfile found."); },
@@ -112,7 +118,7 @@ pub fn app() {
       }
     }
 
-    text = fs::File::open("justfile")
+    text = fs::File::open(name)
       .unwrap_or_else(|error| die!("Error opening justfile: {}", error))
       .slurp()
       .unwrap_or_else(|error| die!("Error reading justfile: {}", error));

src/integration.rs

@@ -3,7 +3,7 @@ extern crate brev;
 extern crate regex;
 
 use tempdir::TempDir;
-use super::std::process::Command;
+use super::std::{fs, path, process};
 
 fn integration_test(
   args:            &[&str],
@@ -13,13 +13,13 @@ fn integration_test(
   expected_stderr: &str,
 ) {
   let tmp = TempDir::new("just-integration")
-    .unwrap_or_else(|err| panic!("tmpdir: failed to create temporary directory: {}", err));
+    .unwrap_or_else(|err| panic!("integration test: failed to create temporary directory: {}", err));
   let mut path = tmp.path().to_path_buf();
   path.push("justfile");
   brev::dump(path, justfile);
   let mut binary = super::std::env::current_dir().unwrap();
   binary.push("./target/debug/just");
-  let output = Command::new(binary)
+  let output = process::Command::new(binary)
     .current_dir(tmp.path())
     .args(args)
     .output()
@@ -50,6 +50,97 @@ fn integration_test(
   }
 }
 
+fn search_test<P: AsRef<path::Path>>(path: P) {
+  let mut binary = super::std::env::current_dir().unwrap();
+  binary.push("./target/debug/just");
+  let output = process::Command::new(binary)
+    .current_dir(path)
+    .output()
+    .expect("just invocation failed");
+
+  assert_eq!(output.status.code().unwrap(), 0);
+
+  let stdout = super::std::str::from_utf8(&output.stdout).unwrap();
+  assert_eq!(stdout, "ok\n");
+
+  let stderr = super::std::str::from_utf8(&output.stderr).unwrap();
+  assert_eq!(stderr, "echo ok\n");
+}
+
+#[test]
+fn test_justfile_search() {
+  let tmp = TempDir::new("just-test-justfile-search")
+    .expect("test justfile search: failed to create temporary directory");
+  let mut path = tmp.path().to_path_buf();
+  path.push("justfile");
+  brev::dump(&path, "default:\n\techo ok");
+  path.pop();
+
+  path.push("a");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("b");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("c");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("d");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+
+  search_test(path);
+}
+
+#[test]
+fn test_capitalized_justfile_search() {
+  let tmp = TempDir::new("just-test-justfile-search")
+    .expect("test justfile search: failed to create temporary directory");
+  let mut path = tmp.path().to_path_buf();
+  path.push("Justfile");
+  brev::dump(&path, "default:\n\techo ok");
+  path.pop();
+
+  path.push("a");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("b");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("c");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("d");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+
+  search_test(path);
+}
+
+#[test]
+fn test_capitalization_priority() {
+  let tmp = TempDir::new("just-test-justfile-search")
+    .expect("test justfile search: failed to create temporary directory");
+  let mut path = tmp.path().to_path_buf();
+  path.push("justfile");
+  brev::dump(&path, "default:\n\techo ok");
+  path.pop();
+  path.push("Justfile");
+  brev::dump(&path, "default:\n\techo fail");
+  path.pop();
+
+  // if we see "default\n\techo fail" in `justfile` then we're running
+  // in a case insensitive filesystem, so just bail
+  path.push("justfile");
+  if brev::slurp(&path) == "default:\n\techo fail" {
+    return;
+  }
+  path.pop();
+
+  path.push("a");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("b");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("c");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+  path.push("d");
+  fs::create_dir(&path).expect("test justfile search: failed to create intermediary directory");
+
+  search_test(path);
+}
+
 #[test]
 fn default() {
   integration_test(