Bug 749258: Have toolkit/devtools/debugger xpcshell tests register a listener for Components.utils.reportError, so tests fail when they throw an exception. r=past

toolkit/devtools/debugger/dbg-client.jsm

@@ -375,10 +375,10 @@ DebuggerClient.prototype = {
    */
   request: function DC_request(aRequest, aOnResponse) {
     if (!this._connected) {
-      throw "Have not yet received a hello packet from the server.";
+      throw Error("Have not yet received a hello packet from the server.");
     }
     if (!aRequest.to) {
-      throw "Request packet has no destination.";
+      throw Error("Request packet has no destination.");
     }
 
     this._pendingRequests.push({ to: aRequest.to,
@@ -449,7 +449,7 @@ DebuggerClient.prototype = {
         onResponse(aPacket);
       }
     } catch(ex) {
-      dumpn("Error handling response: " + ex + " - " + ex.stack);
+      dumpn("Error handling response: " + ex + " - stack:\n" + ex.stack);
       Cu.reportError(ex);
     }
 
@@ -536,7 +536,7 @@ ThreadClient.prototype = {
 
   _assertPaused: function TC_assertPaused(aCommand) {
     if (!this.paused) {
-      throw aCommand + " command sent while not paused.";
+      throw Error(aCommand + " command sent while not paused.");
     }
   },
 

toolkit/devtools/debugger/server/dbg-server.js

@@ -63,6 +63,17 @@ function dbg_assert(cond, e) {
   }
 }
 
+/* Turn the error e into a string, without fail. */
+function safeErrorString(aError) {
+  try {
+    var s = aError.toString();
+    if (typeof s === "string")
+      return s;
+  } catch (ee) { }
+
+  return "<failed trying to find error description>";
+}
+
 loadSubScript.call(this, "chrome://global/content/devtools/dbg-transport.js");
 
 // XPCOM constructors
@@ -445,11 +456,14 @@ DebuggerServerConnection.prototype = {
       } catch(e) {
         Cu.reportError(e);
         ret = { error: "unknownError",
-                message: "An unknown error has occurred while processing request." };
+                message: ("error occurred while processing '" + aPacket.type +
+                          "' request: " + safeErrorString(e)) };
       }
     } else {
       ret = { error: "unrecognizedPacketType",
-              message: 'Actor "' + actor.actorID + '" does not recognize the packet type "' + aPacket.type + '"' };
+              message: ('Actor "' + actor.actorID +
+                        '" does not recognize the packet type "' +
+                        aPacket.type + '"') };
     }
 
     if (!ret) {

toolkit/devtools/debugger/tests/unit/head_dbg.js

@@ -16,6 +16,52 @@ Services.prefs.setBoolPref("devtools.debugger.log", true);
 Cu.import("resource:///modules/devtools/dbg-server.jsm");
 Cu.import("resource:///modules/devtools/dbg-client.jsm");
 
+// Convert an nsIScriptError 'aFlags' value into an appropriate string.
+function scriptErrorFlagsToKind(aFlags) {
+  var kind;
+  if (aFlags & Ci.nsIScriptError.warningFlag)
+    kind = "warning";
+  if (aFlags & Ci.nsIScriptError.exceptionFlag)
+    kind = "exception";
+  else
+    kind = "error";
+
+  if (aFlags & Ci.nsIScriptError.strictFlag)
+    kind = "strict " + kind;
+
+  return kind;
+}
+
+// Register a console listener, so console messages don't just disappear
+// into the ether.
+let errorCount = 0;
+let listener = {
+  observe: function (aMessage) {
+    errorCount++;
+    try {
+      // If we've been given an nsIScriptError, then we can print out
+      // something nicely formatted, for tools like Emacs to pick up.
+      var scriptError = aMessage.QueryInterface(Ci.nsIScriptError);
+      dump(aMessage.sourceName + ":" + aMessage.lineNumber + ": " +
+           scriptErrorFlagsToKind(aMessage.flags) + ": " +
+           aMessage.errorMessage + "\n");
+      var string = aMessage.errorMessage;
+    } catch (x) {
+      // Be a little paranoid with message, as the whole goal here is to lose
+      // no information.
+      try {
+        var string = "" + aMessage.message;
+      } catch (x) {
+        var string = "<error converting error message to string>";
+      }
+    }
+
+    do_throw("head_dbg.js got console message: " + string + "\n");
+  }
+};
+
+let consoleService = Cc["@mozilla.org/consoleservice;1"].getService(Ci.nsIConsoleService);
+consoleService.registerListener(listener);
 
 function check_except(func)
 {