Add serve snapshot test for empty project

rojo-test/src/util.rs

@@ -1,4 +1,10 @@
-use std::path::{Path, PathBuf};
+use std::{
+    fs, io,
+    path::{Path, PathBuf},
+    process::Child,
+};
+
+use walkdir::WalkDir;
 
 pub fn get_rojo_path() -> PathBuf {
     let working_dir = get_working_dir_path();
@@ -29,3 +35,37 @@ pub fn get_serve_tests_path() -> PathBuf {
     let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
     manifest_dir.join("serve-tests")
 }
+
+/// Recursively walk a directory and copy each item to the equivalent location
+/// in another directory. Equivalent to `cp -r src/* dst`
+pub fn copy_recursive(from: &Path, to: &Path) -> io::Result<()> {
+    for entry in WalkDir::new(from) {
+        let entry = entry?;
+        let path = entry.path();
+        let new_path = to.join(path.strip_prefix(from).unwrap());
+
+        let file_type = entry.file_type();
+
+        if file_type.is_dir() {
+            match fs::create_dir(new_path) {
+                Ok(_) => {}
+                Err(err) => match err.kind() {
+                    io::ErrorKind::AlreadyExists => {}
+                    _ => panic!(err),
+                },
+            }
+        } else {
+            fs::copy(path, new_path)?;
+        }
+    }
+
+    Ok(())
+}
+
+pub struct KillOnDrop(pub Child);
+
+impl Drop for KillOnDrop {
+    fn drop(&mut self) {
+        let _ = self.0.kill();
+    }
+}