experimental(debugger): make element explorer work with node 0.12.0

Node has changed its debugger significantly in 0.12.0, and
these changes are necessary to get it to work now.

Author: hankduan

lib/debugger/clients/explorer.js

@@ -1,5 +1,5 @@
 var repl = require('repl');
-var baseDebugger = require('_debugger');
+var debuggerCommons = require('../debuggerCommons');
 var CommandRepl = require('../modes/commandRepl');
 
 /**
@@ -9,7 +9,7 @@ var CommandRepl = require('../modes/commandRepl');
  * @constructor
  */
 var WdRepl = function() {
-  this.client = new baseDebugger.Client();
+  this.client;
   this.replServer;
   this.cmdRepl;
 };
@@ -19,20 +19,8 @@ var WdRepl = function() {
  * @private
  */
 WdRepl.prototype.initClient_ = function() {
-  var client = this.client;
-
-  client.once('ready', function() {
-
-    client.setBreakpoint({
-      type: 'scriptRegExp',
-      target: '.*executors\.js', //jshint ignore:line
-      line: 37
-    }, function() {});
-  });
-
-  var host = 'localhost';
-  var port = process.argv[2] || 5858;
-  client.connect(port, host); // TODO - might want to add retries here.
+  this.client = 
+      debuggerCommons.attachDebugger(process.argv[2], process.argv[3]);
 };
 
 /**
@@ -44,7 +32,7 @@ WdRepl.prototype.initClient_ = function() {
  * @param {function} callback
  */
 WdRepl.prototype.stepEval_ = function(cmd, context, filename, callback) {
-  cmd = cmd.slice(1, cmd.length - 2);
+  cmd = debuggerCommons.trimReplCmd(cmd);
   this.cmdRepl.stepEval(cmd, callback);
 };
 

lib/debugger/clients/wddebugger.js

@@ -1,5 +1,5 @@
 var repl = require('repl');
-var baseDebugger = require('_debugger');
+var debuggerCommons = require('../debuggerCommons');
 var CommandRepl = require('../modes/commandRepl');
 var DebuggerRepl = require('../modes/debuggerRepl');
 
@@ -11,7 +11,7 @@ var DebuggerRepl = require('../modes/debuggerRepl');
  * @constructor
  */
 var WdDebugger = function() {
-  this.client = new baseDebugger.Client();
+  this.client;
   this.replServer;
 
   // repl is broken into 'command repl' and 'debugger repl'.
@@ -26,28 +26,17 @@ var WdDebugger = function() {
  * @private
  */
 WdDebugger.prototype.initClient_ = function() {
-  var client = this.client;
-
-  client.once('ready', function() {
+  this.client = 
+      debuggerCommons.attachDebugger(process.argv[2], process.argv[3]);
+  this.client.once('ready', function() {
     console.log(' ready\n');
-
-    client.setBreakpoint({
-      type: 'scriptRegExp',
-      target: '.*executors\.js', //jshint ignore:line
-      line: 37
-    }, function() {
-      console.log('press c to continue to the next webdriver command');
-      console.log('press d to continue to the next debugger statement');
-      console.log('type "repl" to enter interactive mode');
-      console.log('type "exit" to break out of interactive mode');
-      console.log('press ^C to exit');
-      console.log();
-    });
+    console.log('press c to continue to the next webdriver command');
+    console.log('press d to continue to the next debugger statement');
+    console.log('type "repl" to enter interactive mode');
+    console.log('type "exit" to break out of interactive mode');
+    console.log('press ^C to exit');
+    console.log();
   });
-
-  var host = 'localhost';
-  var port = process.argv[2] || 5858;
-  client.connect(port, host); // TODO - might want to add retries here.
 };
 
 /**
@@ -60,19 +49,26 @@ WdDebugger.prototype.initClient_ = function() {
  */
 WdDebugger.prototype.stepEval_ = function(cmd, context, filename, callback) {
   // The loop won't come back until 'callback' is called.
-  // Strip out the () which the REPL adds and the new line.
   // Note - node's debugger gets around this by adding custom objects
   // named 'c', 's', etc to the REPL context. They have getters which
   // perform the desired function, and the callback is stored for later use.
   // Think about whether this is a better pattern.
-  cmd = cmd.slice(1, cmd.length - 2);
+
+  cmd = debuggerCommons.trimReplCmd(cmd);
 
   if (this.currentRepl === this.dbgRepl && cmd === 'repl' ||
       this.currentRepl === this.cmdRepl && cmd === 'exit') {
     // switch repl mode
     this.currentRepl =
         this.currentRepl === this.dbgRepl ? this.cmdRepl : this.dbgRepl;
-    this.replServer.prompt = this.currentRepl.prompt;
+    // For node backward compatibility. In older versions of node `setPrompt`
+    // does not exist, and we set the prompt by overwriting `replServer.prompt`
+    // directly.
+    if (this.replServer.setPrompt) {
+      this.replServer.setPrompt(this.currentRepl.prompt);
+    } else {
+      this.replServer.prompt = this.currentRepl.prompt;
+    }
     this.replServer.complete = this.currentRepl.complete.bind(this.currentRepl);
     callback();
   } else {

lib/debugger/debuggerCommons.js

@@ -0,0 +1,61 @@
+var baseDebugger = require('_debugger');
+
+/**
+ * Create a debugger client and attach to a running protractor process.
+ * Set a break point at webdriver executor. 
+ * @param {number} pid Pid of the process to attach the debugger to.
+ * @param {number=} opt_port Port to set up the debugger connection over. 
+ * @return {!baseDebugger.Client} The connected debugger client.
+ */
+exports.attachDebugger = function(pid, opt_port) {
+  var client = new baseDebugger.Client();
+
+  client.once('ready', function() {
+    client.setBreakpoint({
+      type: 'scriptRegExp',
+      target: '.*executors\.js', //jshint ignore:line
+      line: 37
+    }, function() {});
+  });
+
+  process.debugPort = opt_port || 5858;
+  // Call this private function instead of sending SIGUSR1 because Windows.
+  process._debugProcess(pid);
+
+  var host = 'localhost';
+  var connectWithRetry = function(attempts) {
+    var socket = client.connect(process.debugPort, host);
+    socket.on('connect', function() {
+      client.reqContinue(function() {
+        // Intentionally blank.
+      });
+    });
+    socket.on('error', function(e) {
+      if (attempts === 1) {
+        throw e;
+      } else {
+        setTimeout(function() {
+          connectWithRetry(attempts - 1);
+        }, 200);
+      }
+    });
+  };
+  connectWithRetry(10);
+
+  return client;
+};
+
+/**
+ * Trim excess symbols from the repl command so that it is consistent with
+ * the user input. 
+ * @param {string} cmd Cmd provided by the repl server.
+ * @return {string} The trimmed cmd.
+ */
+exports.trimReplCmd = function(cmd) {
+  // Given user input 'foobar', some versions of node provide '(foobar\n)',
+  // while other versions of node provide 'foobar\n'. 
+  if (cmd.length >= 2 && cmd[0] === '(' && cmd[cmd.length - 1] === ')') {
+    cmd = cmd.substring(1, cmd.length - 1);
+  }
+  return cmd.slice(0, cmd.length - 1);
+};

lib/protractor.js

@@ -653,26 +653,26 @@ Protractor.prototype.initDebugger_ = function(debuggerClientPath, opt_debugPort)
     return asString;
   };
 
-  if (opt_debugPort) {
-    process.debugPort = opt_debugPort;
-  }
-
-  // Call this private function instead of sending SIGUSR1 because Windows.
-  process._debugProcess(process.pid);
-
+  var vm_ = require('vm');
+  var browserUnderDebug = this;
   var flow = webdriver.promise.controlFlow();
-  var pausePromise = flow.execute(function() {
+
+  flow.execute(function() {    
     log.puts('Starting WebDriver debugger in a child process. Pause is ' +
         'still beta, please report issues at github.com/angular/protractor\n');
     var nodedebug = require('child_process').
-        fork(debuggerClientPath, [process.debugPort]);
+        fork(debuggerClientPath, 
+            [process.pid, opt_debugPort || process.debugPort]);
     process.on('exit', function() {
       nodedebug.kill('SIGTERM');
-    });
+    });    
   });
-
-  var vm_ = require('vm');
-  var browserUnderDebug = this;
+  
+  var pausePromise = flow.timeout(1000, 'waiting for debugger to attach')
+      .then(function() {
+        // Necessary for backward compatibility with node < 0.12.0
+        browserUnderDebug.executeScript_('', 'empty debugger hook');
+      });
 
   // Helper used only by debuggers at './debugger/modes/*.js' to insert code
   // into the control flow.
@@ -773,8 +773,6 @@ Protractor.prototype.initDebugger_ = function(debuggerClientPath, opt_debugPort)
       return found;
     });
   };
-
-  flow.timeout(1000, 'waiting for debugger to attach');
 };
 
 /**