test: add extensible browser evaluation harness

evals/browser/lib/process.mjs

@@ -0,0 +1,71 @@
+import { spawn } from "node:child_process";
+
+const MAX_CAPTURE_BYTES = 4 * 1024 * 1024;
+
+function appendCaptured(current, chunk) {
+  if (current.length >= MAX_CAPTURE_BYTES) return current;
+  return `${current}${chunk}`.slice(0, MAX_CAPTURE_BYTES);
+}
+
+export function runProcess(command, args, { cwd, env, timeoutMs = 300_000 } = {}) {
+  return new Promise((resolve) => {
+    const startedAt = Date.now();
+    let stdout = "";
+    let stderr = "";
+    let timedOut = false;
+    let settled = false;
+    const child = spawn(command, args, {
+      cwd,
+      env: { ...process.env, ...env },
+      shell: false,
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+
+    child.stdout.on("data", (chunk) => {
+      stdout = appendCaptured(stdout, chunk.toString());
+    });
+    child.stderr.on("data", (chunk) => {
+      stderr = appendCaptured(stderr, chunk.toString());
+    });
+
+    const timeout = setTimeout(() => {
+      timedOut = true;
+      child.kill("SIGTERM");
+      setTimeout(() => child.kill("SIGKILL"), 2_000).unref();
+    }, timeoutMs);
+
+    const finish = (result) => {
+      if (settled) return;
+      settled = true;
+      clearTimeout(timeout);
+      resolve({
+        command,
+        args,
+        stdout,
+        stderr,
+        timedOut,
+        durationMs: Date.now() - startedAt,
+        ...result,
+      });
+    };
+
+    child.once("error", (error) => finish({ exitCode: null, signal: null, error: error.message }));
+    child.once("close", (exitCode, signal) => finish({ exitCode, signal }));
+  });
+}
+
+export function substituteArgs(args, values) {
+  return args.map((argument) => {
+    let result = argument;
+    for (const [key, value] of Object.entries(values)) {
+      result = result.replaceAll(`{${key}}`, String(value));
+    }
+    return result;
+  });
+}
+
+export function countPattern(text, pattern) {
+  if (!pattern) return null;
+  const matches = text.match(new RegExp(pattern, "g"));
+  return matches?.length ?? 0;
+}