toolkit: the tool program, read_file and write_file

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/toolkit/tests/support/mod.rs

@@ -0,0 +1,68 @@
+//! Running the `toolkit` binary as `brokerd` does: arguments on standard input. Do not edit.
+
+#![allow(dead_code)] // each test file uses its own part
+
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::process::{Command, Stdio};
+use std::sync::atomic::{AtomicU32, Ordering};
+
+static NEXT: AtomicU32 = AtomicU32::new(0);
+
+/// A temporary directory, removed when dropped.
+pub struct TempDir(pub PathBuf);
+
+impl TempDir {
+    pub fn new(tag: &str) -> TempDir {
+        let n = NEXT.fetch_add(1, Ordering::SeqCst);
+        let path = std::env::temp_dir().join(format!("tk-{tag}-{}-{n}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&path);
+        std::fs::create_dir_all(&path).unwrap();
+        TempDir(path)
+    }
+    pub fn path(&self) -> &Path {
+        &self.0
+    }
+    /// The path of `name` inside, as a string (the tools take strings).
+    pub fn at(&self, name: &str) -> String {
+        self.0.join(name).to_str().unwrap().to_string()
+    }
+}
+
+impl Drop for TempDir {
+    fn drop(&mut self) {
+        let _ = std::fs::remove_dir_all(&self.0);
+    }
+}
+
+pub struct Ran {
+    pub code: i32,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+/// Run `toolkit <args…>` with `input` on standard input.
+pub fn toolkit(args: &[&str], input: &[u8]) -> Ran {
+    let mut child = Command::new(env!("CARGO_BIN_EXE_toolkit"))
+        .args(args)
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    let mut stdin = child.stdin.take().unwrap();
+    // A broken pipe here only means toolkit stopped reading, which some tests expect.
+    let _ = stdin.write_all(input);
+    drop(stdin);
+    let out = child.wait_with_output().unwrap();
+    Ran {
+        code: out.status.code().unwrap_or(-1),
+        stdout: String::from_utf8(out.stdout).unwrap(),
+        stderr: String::from_utf8_lossy(&out.stderr).into_owned(),
+    }
+}
+
+/// The JSON for one argument struct.
+pub fn json<T: serde::Serialize>(value: &T) -> Vec<u8> {
+    serde_json::to_vec(value).unwrap()
+}