From f70ad71f9c707f6038b67075f7fee33f3611295f Mon Sep 17 00:00:00 2001
From: Florian Bruhin <git@the-compiler.org>
Date: Wed, 19 Feb 2014 11:10:26 +0100
Subject: [PATCH] Add error strings to exceptions

---
 qutebrowser/app.py               | 2 +-
 qutebrowser/commands/template.py | 3 ++-
 qutebrowser/commands/utils.py    | 4 ++--
 qutebrowser/models/completion.py | 4 ++--
 qutebrowser/utils/about.py       | 2 +-
 qutebrowser/utils/url.py         | 6 ++++--
 6 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/qutebrowser/app.py b/qutebrowser/app.py
index e29e7f9f4..dbac5af7a 100644
--- a/qutebrowser/app.py
+++ b/qutebrowser/app.py
@@ -409,7 +409,7 @@ class QuteBrowser(QApplication):
             Always raises Exception.
 
         """
-        raise Exception
+        raise Exception("Forced crash")
 
     @pyqtSlot()
     def shutdown(self, do_quit=True):
diff --git a/qutebrowser/commands/template.py b/qutebrowser/commands/template.py
index 857e6ffe8..087589bb3 100644
--- a/qutebrowser/commands/template.py
+++ b/qutebrowser/commands/template.py
@@ -74,7 +74,8 @@ class Command(QObject):
                 (self.nargs == '?' and len(args) > 1) or
                 (self.nargs == '+' and len(args) < 1)):
             # for nargs == '*', anything is okay
-            raise ArgumentCountError
+            raise ArgumentCountError("{} args expected, but got {}".format(
+                self.nargs, len(args)))
 
     def run(self, args=None, count=None):
         """Run the command.
diff --git a/qutebrowser/commands/utils.py b/qutebrowser/commands/utils.py
index 89a77f9a6..5f6225847 100644
--- a/qutebrowser/commands/utils.py
+++ b/qutebrowser/commands/utils.py
@@ -160,12 +160,12 @@ class CommandParser(QObject):
         """
         parts = text.strip().split(maxsplit=1)
         if not parts:
-            raise NoSuchCommandError
+            raise NoSuchCommandError("No command given")
         cmdstr = parts[0]
         try:
             cmd = cmd_dict[cmdstr]
         except KeyError:
-            raise NoSuchCommandError(cmdstr)
+            raise NoSuchCommandError("Command {} not found.".format(cmdstr))
 
         if len(parts) == 1:
             args = []
diff --git a/qutebrowser/models/completion.py b/qutebrowser/models/completion.py
index e738954e6..644a38593 100644
--- a/qutebrowser/models/completion.py
+++ b/qutebrowser/models/completion.py
@@ -362,7 +362,7 @@ class CompletionItem():
         elif role == Qt.UserRole:
             return self._marks
         else:
-            raise ValueError
+            raise ValueError("Invalid role {}".format(role))
 
     def setdata(self, column, value, role=Qt.DisplayRole):
         """Set the data for column/role to value.
@@ -381,7 +381,7 @@ class CompletionItem():
         elif role == Qt.UserRole:
             self._marks = value
         else:
-            raise ValueError
+            raise ValueError("Invalid role {}".format(role))
 
     def column_count(self):
         """Get the column count in the item.
diff --git a/qutebrowser/utils/about.py b/qutebrowser/utils/about.py
index 27cbeb1c0..6e3496a94 100644
--- a/qutebrowser/utils/about.py
+++ b/qutebrowser/utils/about.py
@@ -52,7 +52,7 @@ def handle(url):
 
     """
     if not is_about_url(url):
-        raise ValueError
+        raise ValueError("URL {} is not an about URL".format(url))
     handler = getattr(AboutHandlers, _transform_url(url))
     return handler()
 
diff --git a/qutebrowser/utils/url.py b/qutebrowser/utils/url.py
index 4691e66df..7e8a14bf8 100644
--- a/qutebrowser/utils/url.py
+++ b/qutebrowser/utils/url.py
@@ -54,8 +54,10 @@ def _get_search_url(txt):
                                      fallback=None)
         term = txt
         logging.debug('engine: default, term "{}"'.format(txt))
-    if template is None or not term:
-        raise ValueError
+    if template is None:
+        raise ValueError("Search template is None")
+    if not term:
+        raise ValueError("No search term given")
     return QUrl.fromUserInput(template.format(urllib.parse.quote(term)))