feat: auto-resume on start breakpoint

Author: dolsem

lib/_inspect.js

@@ -170,7 +170,19 @@ class NodeInspector {
     this.domainNames.forEach((domain) => {
       this[domain] = createAgentProxy(domain, this.client);
     });
+    let startBreakReached = false;
     this.handleDebugEvent = (fullName, params) => {
+      if (!startBreakReached &&
+          process.env.NODE_INSPECT_RESUME_ON_START === '1' &&
+          fullName === 'Debugger.paused' &&
+          params && params.reason === 'Break on start') {
+        startBreakReached = true;
+        debuglog('Paused on start, but NODE_INSPECT_RESUME_ON_START' +
+                 ' environment variable is set to 1, resuming');
+        this.client.callMethod('Debugger.resume');
+        return;
+      }
+
       const [domain, name] = fullName.split('.');
       if (domain in this) {
         this[domain].emit(name, params);

test/cli/launch.test.js

@@ -174,3 +174,23 @@ test('run after quit / restart', (t) => {
     .then(() => cli.quit())
     .then(null, onFatal);
 });
+
+test('auto-resume on start if the environment variable is defined', (t) => {
+  const script = Path.join('examples', 'break.js');
+
+  const cli = startCLI([script], [], {
+    env: { NODE_INSPECT_RESUME_ON_START: '1' }
+  });
+
+  return cli.waitForInitialBreak()
+    .then(() => {
+      t.match(
+        cli.breakInfo,
+        { filename: script, line: 10 },
+        'skips to the first breakpoint');
+    })
+    .then(() => cli.quit())
+    .then((code) => {
+      t.equal(code, 0, 'exits with success');
+    });
+});

test/cli/start-cli.js

@@ -20,8 +20,8 @@ function isPreBreak(output) {
   return /Break on start/.test(output) && /1 \(function \(exports/.test(output);
 }
 
-function startCLI(args, flags = []) {
-  const child = spawn(process.execPath, [...flags, CLI, ...args]);
+function startCLI(args, flags = [], spawnOpts = {}) {
+  const child = spawn(process.execPath, [...flags, CLI, ...args], spawnOpts);
   let isFirstStdoutChunk = true;
 
   const outputBuffer = [];