testing_framework: working directory support

std::process::Command::current_dir() works differently on Windows and
Unix. On Unix, the current directory is set before spawning the child
process which can lead to incorrect file path for child process but on
Windows it works as expected, sets the current working directory after
spawning the child process. A simple workaround for this is to use
absolute paths.

See rust-lang/rust#37868 for more details.

testing_framework/src/main.rs

@@ -116,6 +116,11 @@ impl Command {
         }
     }
 
+    pub fn current_dir<P: AsRef<Path>>(&mut self, dir: P) -> &mut Self {
+        self.command.current_dir(dir);
+        self
+    }
+
     pub fn stdout<T: Into<process::Stdio>>(&mut self, cfg: T) -> &mut Self {
         self.command.stdout(cfg);
         self
@@ -243,8 +248,9 @@ fn main() {
         let (progress_server, progress_server_name): (ipc::IpcOneShotServer<u64>, _) =
             ipc::IpcOneShotServer::new().unwrap();
 
-        let mut command = Command::new(exec_path);
+        let mut command = Command::new(std::fs::canonicalize(exec_path).unwrap());
         command
+            .current_dir(std::fs::canonicalize(working_directory_path).unwrap())
             .stdout(std::process::Stdio::null())
             .stderr(std::process::Stdio::null())
             .arg("--headless")