Move workspace creation outside of runtime instantiation

tests/utils.rs

@@ -0,0 +1,54 @@
+use std::env;
+use std::ffi::OsStr;
+use std::fs::{self, File};
+use std::io;
+use std::io::prelude::*;
+use std::path::{Component, Path};
+use std::time::SystemTime;
+
+fn read_to_end<P: AsRef<Path>>(path: P) -> Result<Vec<u8>, io::Error> {
+    let mut buf: Vec<u8> = Vec::new();
+    let mut file = File::open(path)?;
+    file.read_to_end(&mut buf)?;
+    Ok(buf)
+}
+
+pub fn read_wasm<P: AsRef<Path>>(path: P) -> Result<Vec<u8>, String> {
+    let data = read_to_end(path).map_err(|err| err.to_string())?;
+    if data.starts_with(&[b'\0', b'a', b's', b'm']) {
+        Ok(data)
+    } else {
+        Err("Invalid Wasm file encountered".to_owned())
+    }
+}
+
+pub fn prepare_workspace<S: AsRef<str>>(exe_name: S) -> Result<String, String> {
+    let mut workspace = env::temp_dir();
+    let time_now = SystemTime::now()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .map_err(|err| err.to_string())?;
+    let subdir = format!(
+        "wasi_common_tests_{}_{}",
+        exe_name.as_ref(),
+        time_now.as_secs()
+    );
+    workspace.push(subdir);
+    fs::create_dir(workspace.as_path()).map_err(|err| err.to_string())?;
+
+    Ok(workspace
+        .as_os_str()
+        .to_str()
+        .ok_or("couldn't convert to str".to_owned())?
+        .to_string())
+}
+
+pub fn extract_exec_name_from_path<P: AsRef<Path>>(path: P) -> Result<String, String> {
+    Ok(path
+        .as_ref()
+        .components()
+        .next_back()
+        .map(Component::as_os_str)
+        .and_then(OsStr::to_str)
+        .ok_or("couldn't convert to str".to_owned())?
+        .to_owned())
+}