Add coverage tool

tools/coverage.dart

Index: tools/coverage.dart
===================================================================
--- tools/coverage.dart	(revision 0)
+++ tools/coverage.dart	(revision 0)
@@ -0,0 +1,492 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// This test forks a second vm process that runs a dart script as
+// a debug target, single stepping through the entire program, and
+// recording each breakpoint. At the end, a coverage map of the source
+// is printed.
+//
+// Usage: dart coverage.dart [--wire] [--verbose] target_script.dart
+//
+//   --wire      see json messages sent between the processes.
+//   --verbose   see the stdout and stderr output of the debug
+//               target process.
+
+import "dart:io";
+import "dart:utf";
+import "dart:json" as JSON;
+
+
+// Whether or not to print debug target process on the console.
+var showDebuggeeOutput = false;
+
+// Whether or not to print the debugger wire messages on the console.
+var verboseWire = false;
+
+
+class Program {
+  static int numBps = 0;
+
+  // Maps source code url to source.
+  static var sources = new Map<String, Source>();
+
+  // Takes a JSON Debugger response and increments the count for
+  // the source position.
+  static void recordBp(Debugger debugger, Map<String,dynamic> msg) {
+    // Progress indicator.
+    if (++numBps % 100 == 0) print(numBps);
+    var location = msg["params"]["location"];
+    if (location == null) return;
+    String url = location["url"];
+    assert(url != null);
+    int tokenPos = location["tokenOffset"];;
+    Source s = sources[url];
+    if (s == null) {
+      debugger.GetLineNumberTable(url);
+      s = new Source(url);
+      sources[url] = s;
+    }
+    s.recordBp(tokenPos);
+  }
+
+  // Prints the annotated source code.
+  static void printCoverage() {
+    print("Coverage info collected from $numBps breakpoints:");
+    for(Source s in sources.values) s.printCoverage();
+  }
+}
+
+
+class Source {
+  final String url;
+
+  // Maps token position to breakpoint count.
+  final tokenCounts = new Map<int,int>();
+
+  // Maps token position to line number.
+  final tokenPosToLine = new Map<int,int>();
+
+  Source(this.url);
+
+  void recordBp(int tokenPos) {
+    var count = tokenCounts[tokenPos];
+    tokenCounts[tokenPos] = count == null ? 1 : count + 1;
+  }
+
+  void SetLineInfo(List lineInfoTable) {
+    // Each line is encoded as an array with first element being the line
+    // number, followed by pairs of (tokenPosition, textOffset).
+    lineInfoTable.forEach((List<int> line) {
+      int lineNumber = line[0];
+      for (int t = 1; t < line.length; t += 2) {
+        assert(tokenPosToLine[line[t]] == null);
+        tokenPosToLine[line[t]] = lineNumber;
+      }
+    });
+  }
+
+  // Print out the annotated source code. For each line that has seen
+  // a breakpoint, print out the maximum breakpoint count for all
+  // tokens in the line.
+  void printCoverage() {
+    var lineCounts = new Map<int,int>();  // BP counts for each line.
+    print(url);
+    tokenCounts.forEach((tp, bpCount) {
+      int lineNumber = tokenPosToLine[tp];
+      var lineCount = lineCounts[lineNumber];
+      // Remember maximum breakpoint count of all tokens in this line.
+      if (lineCount == null || lineCount < bpCount) {
+        lineCounts[lineNumber] = bpCount;
+      }
+    });
+
+    List lines = new File(Uri.parse(url).path).readAsLinesSync();
+    for (int line = 1; line <= lines.length; line++) {
+      String prefix = "      ";
+      if (lineCounts.containsKey(line)) {
+        prefix = lineCounts[line].toString();
+        StringBuffer b = new StringBuffer();
+        for (int i = prefix.length; i < 6; i++) b.write(" ");
+        b.write(prefix);
+        prefix = b.toString();
+      }
+      print("${prefix}|${lines[line-1]}");
+    }
+  }
+}
+
+
+class StepCmd {
+  Map msg;
+  StepCmd(int isolateId) {
+    msg = {"id": 0, "command": "stepInto", "params": {"isolateId": isolateId}};
+  }
+  void handleResponse(Map response) {}
+}
+
+
+class GetLineTableCmd {
+  Map msg;
+  GetLineTableCmd(int isolateId, int libraryId, String url) {
+    msg = { "id": 0,
+            "command":  "getLineNumberTable",
+            "params": { "isolateId" : isolateId,
+                        "libraryId": libraryId,
+                        "url": url } };
+  }
+
+  void handleResponse(Map response) {
+    var url = msg["params"]["url"];
+    Source s = Program.sources[url];
+    assert(s != null);
+    s.SetLineInfo(response["result"]["lines"]);
+  }
+}
+
+
+class Debugger {
+  // Debug target process properties.
+  Process targetProcess;
+  Socket socket;
+  bool cleanupDone = false;
+  JsonBuffer responses = new JsonBuffer();
+  List<String> errors = new List();
+
+  // Data collected from debug target.
+  Map currentMessage = null;  // Currently handled message sent by target.
+  var outstandingCommand = null;
+  var queuedCommand = null;
+  String scriptUrl = null;
+  bool shutdownEventSeen = false;
+  int isolateId = 0;
+  int libraryId = null;
+
+  int nextMessageId = 0;
+  bool isPaused = false;
+  bool pendingAck = false;
+
+  Debugger(this.targetProcess) {
+    var stdoutStringStream = targetProcess.stdout
+        .transform(new StringDecoder())
+        .transform(new LineTransformer());
+    stdoutStringStream.listen((line) {
+      if (showDebuggeeOutput) {
+        print("TARG: $line");
+      }
+      if (line.startsWith("Debugger listening")) {
+        RegExp portExpr = new RegExp(r"\d+");
+        var port = portExpr.stringMatch(line);
+        print("Debug target found listening at port '$port'");
+        openConnection(int.parse(port));
+      }
+    });
+
+    var stderrStringStream = targetProcess.stderr
+        .transform(new StringDecoder())
+        .transform(new LineTransformer());
+    stderrStringStream.listen((line) {
+      if (showDebuggeeOutput) {
+        print("TARG: $line");
+      }
+    });
+  }
+
+  // Handle debugger events, updating the debugger state.
+  void handleEvent(Map<String,dynamic> msg) {
+    if (msg["event"] == "isolate") {
+      if (msg["params"]["reason"] == "created") {
+        isolateId = msg["params"]["id"];
+        assert(isolateId != null);
+        print("Debuggee isolate id $isolateId created.");
+      } else if (msg["params"]["reason"] == "shutdown") {
+        print("Debuggee isolate id ${msg["params"]["id"]} shut down.");
+        shutdownEventSeen = true;
+      }
+    } else if (msg["event"] == "breakpointResolved") {
+      var bpId = msg["params"]["breakpointId"];
+      assert(bpId != null);
+      var isolateId = msg["params"]["isolateId"];
+      assert(isolateId != null);
+      var location = msg["params"]["location"];
+      assert(location != null);
+      print("Isolate $isolateId: breakpoint $bpId resolved"
+            " at location $location");
+      // We may want to maintain a table of breakpoints in the future.
+    } else if (msg["event"] == "paused") {
+      isPaused = true;
+      if (libraryId == null) {
+        libraryId = msg["params"]["location"]["libraryId"];
+        assert(libraryId != null);
+      }
+      if (msg["params"]["reason"] == "breakpoint") {
+        Program.recordBp(this, msg);
+      }
+    } else {
+      error("Error: unknown debugger event received");
+    }
+  }
+
+  // Handle one JSON message object and match it to the
+  // expected events and responses in the debugging script.
+  void handleMessage(Map<String,dynamic> receivedMsg) {
+    currentMessage = receivedMsg;
+    if (receivedMsg["event"] != null) {
+      handleEvent(receivedMsg);
+      if (errorsDetected) {
+        error("Error while handling debugger event");
+        error("Event received from debug target: $receivedMsg");
+      }
+    } else if (receivedMsg["id"] != null) {
+      // This is a response to the last command we sent.
+      int id = receivedMsg["id"];
+      assert(outstandingCommand != null);
+      assert(outstandingCommand.msg["id"] == id);
+      outstandingCommand.handleResponse(receivedMsg);
+      outstandingCommand = null;
+    } else {
+      error("Unexpected message from target");
+    }
+  }
+
+  // Handle data received over the wire from the debug target
+  // process. Split input from JSON wire format into individual
+  // message objects (maps).
+  void handleMessages() {
+    var msg = responses.getNextMessage();
+    while (msg != null) {
+      if (verboseWire) print("RECV: $msg");
+      if (responses.haveGarbage()) {
+        error("Error: leftover text after message: '${responses.buffer}'");
+        error("Previous message may be malformed, was: '$msg'");
+        cleanup();
+        return;
+      }
+      var msgObj = JSON.parse(msg);
+      handleMessage(msgObj);
+      if (errorsDetected) {
+        error("Error while handling message from debug target");
+        error("Message received from debug target: $msg");
+        cleanup();
+        return;
+      }
+      if (shutdownEventSeen) {
+        if (outstandingCommand != null) {
+          error("Error: outstanding command when shutdown received");
+        }
+        cleanup();
+        return;
+      }
+      if (isPaused && (outstandingCommand == null)) {
+        var cmd = queuedCommand;
+        queuedCommand = null;
+        if (cmd == null) {
+          cmd = new StepCmd(isolateId);
+          isPaused = false;
+        }
+        sendMessage(cmd.msg);
+        outstandingCommand = cmd;
+      }
+      msg = responses.getNextMessage();
+    }
+  }
+
+  // Send a debugger command to the target VM.
+  void sendMessage(Map<String,dynamic> msg) {
+    assert(msg["id"] != null);
+    msg["id"] = nextMessageId++;
+    String jsonMsg = JSON.stringify(msg);
+    if (verboseWire) print("SEND: $jsonMsg");
+    socket.write(jsonMsg);
+  }
+
+  void GetLineNumberTable(String url) {
+    assert(queuedCommand == null);
+    queuedCommand = new GetLineTableCmd(isolateId, libraryId, url);
+  }
+  
+  bool get errorsDetected => errors.length > 0;
+
+  // Record error message.
+  void error(String s) {
+    errors.add(s);
+  }
+
+  void openConnection(int portNumber) {
+    Socket.connect("127.0.0.1", portNumber).then((s) {
+      socket = s;
+      var stringStream = socket.transform(new StringDecoder());
+      stringStream.listen(
+          (str) {
+            try {
+              responses.append(str);
+              handleMessages();
+            } catch(e, trace) {
+              print("Unexpected exception:\n$e\n$trace");
+              cleanup();
+            }
+          },
+          onDone: () {
+            print("Connection closed by debug target");
+            cleanup();
+          },
+          onError: (e) {
+            print("Error '$e' detected in input stream from debug target");
+            cleanup();
+          });
+      },
+      onError: (e) {
+        String msg = "Error while connecting to debugee: $e";
+        var trace = getAttachedStackTrace(e);
+        if (trace != null) msg += "\nStackTrace: $trace";
+        error(msg);
+        cleanup();
+     });
+  }
+
+  void cleanup() {
+    if (cleanupDone) return;
+    if (socket != null) {
+      socket.close().catchError((error) {
+        // Print this directly in addition to adding it to the
+        // error message queue, in case the error message queue
+        // gets printed before this error handler is called.
+        print("Error occurred while closing socket: $error");
+        error("Error while closing socket: $error");
+      });
+    }
+    var targetPid = targetProcess.pid;
+    print("Sending kill signal to process $targetPid...");
+    targetProcess.kill();
+    // If the process was already dead exitCode is already
+    // available and we call exit() in the next event loop cycle.
+    // Otherwise this will wait for the process to exit.
+
+    targetProcess.exitCode.then((exitCode) {
+      print("process $targetPid terminated with exit code $exitCode.");
+      if (errorsDetected) {
+        print("\n===== Errors detected: =====");
+        for (int i = 0; i < errors.length; i++) print(errors[i]);
+        print("============================\n");
+      }
+      Program.printCoverage();
+      exit(errors.length);
+    });
+    cleanupDone = true;
+  }
+}
+
+
+// Class to buffer wire protocol data from debug target and
+// break it down to individual json messages.
+class JsonBuffer {
+  String buffer = null;
+
+  append(String s) {
+    if (buffer == null || buffer.length == 0) {
+      buffer = s;
+    } else {
+      buffer = buffer.concat(s);
+    }
+  }
+
+  String getNextMessage() {
+    if (buffer == null) return null;
+    int msgLen = objectLength();
+    if (msgLen == 0) return null;
+    String msg = null;
+    if (msgLen == buffer.length) {
+      msg = buffer;
+      buffer = null;
+    } else {
+      assert(msgLen < buffer.length);
+      msg = buffer.substring(0, msgLen);
+      buffer = buffer.substring(msgLen);
+    }
+    return msg;
+  }
+
+  bool haveGarbage() {
+    if (buffer == null || buffer.length == 0) return false;
+    var i = 0, char = " ";
+    while (i < buffer.length) {
+      char = buffer[i];
+      if (char != " " && char != "\n" && char != "\r" && char != "\t") break;
+      i++;
+    }
+    if (i >= buffer.length) {
+      return false;
+    } else { 
+      return char != "{";
+    }
+  }
+
+  // Returns the character length of the next json message in the
+  // buffer, or 0 if there is only a partial message in the buffer.
+  // The object value must start with '{' and continues to the
+  // matching '}'. No attempt is made to otherwise validate the contents
+  // as JSON. If it is invalid, a later JSON.parse() will fail.
+  int objectLength() {
+    int skipWhitespace(int index) {
+      while (index < buffer.length) {
+        String char = buffer[index];
+        if (char != " " && char != "\n" && char != "\r" && char != "\t") break;
+        index++;
+      }
+      return index;
+    }
+    int skipString(int index) {
+      assert(buffer[index - 1] == '"');
+      while (index < buffer.length) {
+        String char = buffer[index];
+        if (char == '"') return index + 1;
+        if (char == r'\') index++;
+        if (index == buffer.length) return index;
+        index++;
+      }
+      return index;
+    }
+    int index = 0;
+    index = skipWhitespace(index);
+    // Bail out if the first non-whitespace character isn't '{'.
+    if (index == buffer.length || buffer[index] != '{') return 0;
+    int nesting = 0;
+    while (index < buffer.length) {
+      String char = buffer[index++];
+      if (char == '{') {
+        nesting++;
+      } else if (char == '}') {
+        nesting--;
+        if (nesting == 0) return index;
+      } else if (char == '"') {
+        // Strings can contain braces. Skip their content.
+        index = skipString(index);
+      }
+    }
+    return 0;
+  }
+}
+
+
+void main() {
+  var options = new Options();
+  var targetOpts = [ "--debug:0" ];
+  for (String str in options.arguments) {
+    switch (str) {
+      case "--verbose":
+        showDebuggeeOutput = true;
+        break;
+      case "--wire":
+        verboseWire = true;
+        break;
+      default:
+        targetOpts.add(str);
+        break;
+    }
+  }
+
+  Process.start(options.executable, targetOpts).then((Process process) {
+    process.stdin.close();
+    var debugger = new Debugger(process);
+  });
+}