feat: Restore breakpoints on restart

Author: Jan Krems

lib/internal/inspect-repl.js

@@ -432,6 +432,11 @@ function createRepl(inspector) {
   }
 
   function handleBreakpointResolved({ breakpointId, location }) {
+    const script = knownScripts[location.scriptId];
+    const scriptUrl = script && script.url;
+    if (scriptUrl) {
+      Object.assign(location, { scriptUrl });
+    }
     const isExisting = knownBreakpoints.some(bp => {
       if (bp.breakpointId === breakpointId) {
         Object.assign(bp, { location });
@@ -445,6 +450,11 @@ function createRepl(inspector) {
   }
 
   function listBreakpoints() {
+    if (!knownBreakpoints.length) {
+      print('No breakpoints yet');
+      return;
+    }
+
     function formatLocation(location) {
       if (!location) return '<unknown location>';
       const script = knownScripts[location.scriptId];
@@ -571,6 +581,19 @@ function createRepl(inspector) {
       });
   }
 
+  function restoreBreakpoints() {
+    const lastBreakpoints = knownBreakpoints.slice();
+    knownBreakpoints.length = 0;
+    const newBreakpoints = lastBreakpoints
+      .filter(({ location }) => !!location.scriptUrl)
+      .map(({ location }) =>
+        setBreakpoint(location.scriptUrl, location.lineNumber + 1));
+    if (!newBreakpoints.length) return;
+    Promise.all(newBreakpoints).then((results) => {
+      print(`${results.length} breakpoints restored.`);
+    });
+  }
+
   Debugger.on('paused', ({ callFrames, reason /* , hitBreakpoints */ }) => {
     // Save execution context's data
     currentBacktrace = Backtrace.from(callFrames);
@@ -765,7 +788,7 @@ function createRepl(inspector) {
     });
 
     inspector.client.on('ready', () => {
-      // TODO: restore breakpoints
+      restoreBreakpoints();
     });
 
     return repl;

test/cli/preserve-breaks.test.js

@@ -0,0 +1,53 @@
+'use strict';
+const { test } = require('tap');
+
+const startCLI = require('./start-cli');
+
+test('run after quit / restart', (t) => {
+  const cli = startCLI(['examples/three-lines.js']);
+
+  function onFatal(error) {
+    cli.quit();
+    throw error;
+  }
+
+  return cli.waitFor(/break/)
+    .then(() => cli.waitForPrompt())
+    .then(() => cli.command('breakpoints'))
+    .then(() => {
+      t.match(cli.output, 'No breakpoints yet');
+    })
+    .then(() => cli.command('sb(2)'))
+    .then(() => cli.command('sb(3)'))
+    .then(() => cli.command('breakpoints'))
+    .then(() => {
+      t.match(cli.output, '#0 examples/three-lines.js:2');
+      t.match(cli.output, '#1 examples/three-lines.js:3');
+    })
+    .then(() => cli.stepCommand('c')) // hit line 2
+    .then(() => cli.stepCommand('c')) // hit line 3
+    .then(() => {
+      t.match(cli.output, 'break in examples/three-lines.js:3');
+    })
+    .then(() => cli.command('restart'))
+    .then(() => cli.waitFor([/break in examples/, /breakpoints restored/]))
+    .then(() => cli.waitForPrompt())
+    .then(() => {
+      t.match(cli.output, 'break in examples/three-lines.js:1');
+    })
+    .then(() => cli.stepCommand('c'))
+    .then(() => {
+      t.match(cli.output, 'break in examples/three-lines.js:2');
+    })
+    .then(() => cli.stepCommand('c'))
+    .then(() => {
+      t.match(cli.output, 'break in examples/three-lines.js:3');
+    })
+    .then(() => cli.command('breakpoints'))
+    .then(() => {
+      t.match(cli.output, '#0 examples/three-lines.js:2');
+      t.match(cli.output, '#1 examples/three-lines.js:3');
+    })
+    .then(() => cli.quit())
+    .then(null, onFatal);
+});

test/cli/start-cli.js

@@ -40,9 +40,16 @@ function startCLI(args) {
     },
 
     waitFor(pattern, timeout = 2000) {
+      function checkPattern(str) {
+        if (Array.isArray(pattern)) {
+          return pattern.every((p) => p.test(str));
+        }
+        return pattern.test(str);
+      }
+
       return new Promise((resolve, reject) => {
         function checkOutput() {
-          if (pattern.test(getOutput())) {
+          if (checkPattern(getOutput())) {
             tearDown(); // eslint-disable-line no-use-before-define
             resolve();
           }