feat: Working repl eval

Author: Jan Krems

lib/internal/inspect-repl.js

@@ -1,11 +1,43 @@
 'use strict';
 const Repl = require('repl');
+const vm = require('vm');
+
+function toCallback(promise, callback) {
+  function forward(...args) {
+    process.nextTick(() => callback(...args));
+  }
+  promise.then(forward.bind(null, null), forward);
+}
 
 function startRepl(inspector) {
   let repl; // forward declaration
+  let lastCommand;
+
+  function prepareControlCode(input) {
+    if (input === '\n') return lastCommand;
+    // exec process.title => exec("process.title");
+    const match = input.match(/^\s*exec\s+([^\n]*)/);
+    if (match) {
+      lastCommand = `exec(${JSON.stringify(match[1])})`;
+    } else {
+      lastCommand = input;
+    }
+    return lastCommand;
+  }
+
+  function controlEval(input, context, filename, callback) {
+    try {
+      const code = prepareControlCode(input);
+      const result = vm.runInContext(code, context, filename);
 
-  function controlEval(code, ctx, file, cb) {
-    cb(new Error('Not implemented'));
+      if (result && typeof result.then === 'function') {
+        toCallback(result, callback);
+        return;
+      }
+      callback(null, result);
+    } catch (e) {
+      callback(e);
+    }
   }
 
   const replOptions = {

test/cli/launch.test.js

@@ -6,10 +6,16 @@ const startCLI = require('./start-cli');
 tap.test('examples/empty.js', (t) => {
   const cli = startCLI(['examples/empty.js']);
   return cli.waitForPrompt()
-    .then(() => cli.quit())
-    .then((code) => {
+    .then(() => {
       t.match(cli.output, 'debug>', 'prints a prompt');
       t.match(cli.output, '< Debugger listening on port 9229', 'forwards child output');
+    })
+    .then(() => cli.command('["hello", "world"].join(" ")'))
+    .then(() => {
+      t.match(cli.output, 'hello world', 'prints the result');
+    })
+    .then(() => cli.quit())
+    .then((code) => {
       t.equal(code, 0, 'exits with success');
     });
 });

test/cli/start-cli.js

@@ -78,6 +78,13 @@ function startCLI(args) {
       return getOutput();
     },
 
+    command(input) {
+      this.flushOutput();
+      child.stdin.write(input);
+      child.stdin.write('\n');
+      return this.waitForPrompt();
+    },
+
     quit() {
       return new Promise((resolve) => {
         child.stdin.end();