2 files changed, 74 insertions, 3 deletions
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 3b32004..5111a73 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -1277,9 +1277,9 @@ class DocTestRunner:
 
                 # Another chance if they didn't care about the detail.
                 elif self.optionflags & IGNORE_EXCEPTION_DETAIL:
-                    m1 = re.match(r'[^:]*:', example.exc_msg)
-                    m2 = re.match(r'[^:]*:', exc_msg)
-                    if m1 and m2 and check(m1.group(0), m2.group(0),
+                    m1 = re.match(r'(?:[^:]*\.)?([^:]*:)', example.exc_msg)
+                    m2 = re.match(r'(?:[^:]*\.)?([^:]*:)', exc_msg)
+                    if m1 and m2 and check(m1.group(1), m2.group(1),
                                            self.optionflags):
                         outcome = SUCCESS
 
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index fc5153f..873e495 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -864,6 +864,77 @@ detail:
     >>> doctest.DocTestRunner(verbose=False).run(test)
     TestResults(failed=0, attempted=1)
 
+IGNORE_EXCEPTION_DETAIL also ignores difference in exception formatting
+between Python versions. For example, in Python 2.x, the module path of
+the exception is not in the output, but this will fail under Python 3:
+
+    >>> def f(x):
+    ...     r'''
+    ...     >>> from http.client import HTTPException
+    ...     >>> raise HTTPException('message')
+    ...     Traceback (most recent call last):
+    ...     HTTPException: message
+    ...     '''
+    >>> test = doctest.DocTestFinder().find(f)[0]
+    >>> doctest.DocTestRunner(verbose=False).run(test)
+    ... # doctest: +ELLIPSIS
+    **********************************************************************
+    File ..., line 4, in f
+    Failed example:
+        raise HTTPException('message')
+    Expected:
+        Traceback (most recent call last):
+        HTTPException: message
+    Got:
+        Traceback (most recent call last):
+        ...
+        http.client.HTTPException: message
+    TestResults(failed=1, attempted=2)
+
+But in Python 3 the module path is included, and therefore a test must look
+like the following test to succeed in Python 3. But that test will fail under
+Python 2.
+
+    >>> def f(x):
+    ...     r'''
+    ...     >>> from http.client import HTTPException
+    ...     >>> raise HTTPException('message')
+    ...     Traceback (most recent call last):
+    ...     http.client.HTTPException: message
+    ...     '''
+    >>> test = doctest.DocTestFinder().find(f)[0]
+    >>> doctest.DocTestRunner(verbose=False).run(test)
+    TestResults(failed=0, attempted=2)
+
+However, with IGNORE_EXCEPTION_DETAIL, the module name of the exception
+(or its unexpected absence) will be ignored:
+
+    >>> def f(x):
+    ...     r'''
+    ...     >>> from http.client import HTTPException
+    ...     >>> raise HTTPException('message') #doctest: +IGNORE_EXCEPTION_DETAIL
+    ...     Traceback (most recent call last):
+    ...     HTTPException: message
+    ...     '''
+    >>> test = doctest.DocTestFinder().find(f)[0]
+    >>> doctest.DocTestRunner(verbose=False).run(test)
+    TestResults(failed=0, attempted=2)
+
+The module path will be completely ignored, so two different module paths will
+still pass if IGNORE_EXCEPTION_DETAIL is given. This is intentional, so it can
+be used when exceptions have changed module.
+
+    >>> def f(x):
+    ...     r'''
+    ...     >>> from http.client import HTTPException
+    ...     >>> raise HTTPException('message') #doctest: +IGNORE_EXCEPTION_DETAIL
+    ...     Traceback (most recent call last):
+    ...     foo.bar.HTTPException: message
+    ...     '''
+    >>> test = doctest.DocTestFinder().find(f)[0]
+    >>> doctest.DocTestRunner(verbose=False).run(test)
+    TestResults(failed=0, attempted=2)
+
 But IGNORE_EXCEPTION_DETAIL does not allow a mismatch in the exception type:
 
     >>> def f(x):