refactor: specialize exceptions

CoverageException is fine as a base class, but not good to use for
raising (and catching sometimes).  Introduce specialized exceptions that
allow third-party tools to integrate better.

1 files changed, 21 insertions, 2 deletions

diff --git a/coverage/exceptions.py b/coverage/exceptions.py
index de2257a1..c6a7f3da 100644
--- a/coverage/exceptions.py
+++ b/coverage/exceptions.py
@@ -5,12 +5,26 @@
 
 
 class _BaseCoverageException(Exception):
-    """The base of all Coverage exceptions."""
+    """The base-base of all Coverage exceptions."""
     pass
 
 
 class CoverageException(_BaseCoverageException):
-    """An exception raised by a coverage.py function."""
+    """The base class of all exceptions raised by Coverage.py."""
+    pass
+
+
+class ConfigError(_BaseCoverageException):
+    """A problem with a config file, or a value in one."""
+    pass
+
+
+class DataError(CoverageException):
+    """An error in using a data file."""
+    pass
+
+class NoDataError(CoverageException):
+    """We didn't have data to work with."""
     pass
 
 
@@ -29,6 +43,11 @@ class NotPython(CoverageException):
     pass
 
 
+class PluginError(CoverageException):
+    """A plugin misbehaved."""
+    pass
+
+
 class _ExceptionDuringRun(CoverageException):
     """An exception happened while running customer code.