Overwrite vim instead of editor in tests on FreeBSD

On FreeBSD visudo only tries to run /usr/bin/vi, not /usr/bin/editor.
This also changes sudo-rs to run /usr/bin/vi by default for visudo on
FreeBSD.

src/visudo/mod.rs

@@ -303,9 +303,18 @@ fn edit_sudoers_file(
 }
 
 fn editor_path_fallback() -> io::Result<PathBuf> {
-    let path = Path::new("/usr/bin/editor");
-    if can_execute(path) {
-        return Ok(path.to_owned());
+    let editors = if cfg!(target_os = "linux") {
+        &["/usr/bin/editor"][..]
+    } else if cfg!(target_os = "freebsd") {
+        &["/usr/bin/vi"]
+    } else {
+        unimplemented!("unknown default editor for target")
+    };
+    for &editor in editors {
+        let path = Path::new(editor);
+        if can_execute(path) {
+            return Ok(path.to_owned());
+        }
     }
 
     Err(io::Error::new(

test-framework/sudo-compliance-tests/src/visudo.rs

@@ -32,7 +32,10 @@ macro_rules! assert_snapshot {
 }
 
 const TMP_SUDOERS: &str = "/tmp/sudoers";
+#[cfg(not(target_os = "freebsd"))]
 const DEFAULT_EDITOR: &str = "/usr/bin/editor";
+#[cfg(target_os = "freebsd")]
+const DEFAULT_EDITOR: &str = "/usr/bin/vi";
 const LOGS_PATH: &str = "/tmp/logs.txt";
 const CHMOD_EXEC: &str = "100";
 const EDITOR_DUMMY: &str = "#!/bin/sh