Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/wasi-common/tests/wasm_tests/utils.rs

@@ -0,0 +1,30 @@
+use std::fs;
+use std::path::Path;
+use tempfile::{Builder, TempDir};
+
+pub fn read_wasm(path: &Path) -> anyhow::Result<Vec<u8>> {
+    let data = fs::read(path)?;
+    if data.starts_with(&[b'\0', b'a', b's', b'm']) {
+        Ok(data)
+    } else {
+        anyhow::bail!("Invalid Wasm file encountered")
+    }
+}
+
+pub fn prepare_workspace(exe_name: &str) -> anyhow::Result<TempDir> {
+    let prefix = format!("wasi_common_{}", exe_name);
+    let tempdir = Builder::new().prefix(&prefix).tempdir()?;
+    Ok(tempdir)
+}
+
+pub fn extract_exec_name_from_path(path: &Path) -> anyhow::Result<String> {
+    path.file_stem()
+        .and_then(|s| s.to_str())
+        .map(String::from)
+        .ok_or_else(|| {
+            anyhow::anyhow!(
+                "couldn't extract the file stem from path {}",
+                path.display()
+            )
+        })
+}