fix Issue 274 - dont fail when doctest does not know the example location

instead only the last test is shown, this could use some further enhancement

CHANGELOG

@@ -1,6 +1,9 @@
 Changes between 2.3.4 and 2.3.5dev
 -----------------------------------
 
+- Issue 274 - dont try to show full doctest example
+  when doctest does not know the example location
+
 - issue 280 - disable assertion rewriting on buggy CPython 2.6.0
 
 - inject "getfixture()" helper to retrieve fixtures from doctests,

_pytest/doctest.py

@@ -42,17 +42,27 @@ class DoctestItem(pytest.Item):
             example = doctestfailure.example
             test = doctestfailure.test
             filename = test.filename
+            if test.lineno is None:
+                lineno = None
+            else:
                 lineno = test.lineno + example.lineno + 1
             message = excinfo.type.__name__
             reprlocation = ReprFileLocation(filename, lineno, message)
             checker = py.std.doctest.OutputChecker()
             REPORT_UDIFF = py.std.doctest.REPORT_UDIFF
             filelines = py.path.local(filename).readlines(cr=0)
-            i = max(test.lineno, max(0, lineno - 10)) # XXX?
             lines = []
+            if lineno is not None:
+                i = max(test.lineno, max(0, lineno - 10)) # XXX?
                 for line in filelines[i:lineno]:
                     lines.append("%03d %s" % (i+1, line))
                     i += 1
+            else:
+                lines.append('EXAMPLE LOCATION UNKNOWN, not showing all tests of that example')
+                indent = '>>>'
+                for line in example.source.splitlines():
+                    lines.append('??? %s %s' % (indent, line))
+                    indent = '...'
             if excinfo.errisinstance(doctest.DocTestFailure):
                 lines += checker.output_difference(example,
                         doctestfailure.got, REPORT_UDIFF).split("\n")

testing/test_doctest.py

@@ -59,6 +59,26 @@ class TestDoctests:
             "*UNEXPECTED*ZeroDivision*",
         ])
 
+    def test_doctest_linedata_missing(self, testdir):
+        testdir.tmpdir.join('hello.py').write(py.code.Source("""
+            class Fun(object):
+                @property
+                def test(self):
+                    '''
+                    >>> a = 1
+                    >>> 1/0
+                    '''
+            """))
+        result = testdir.runpytest("--doctest-modules")
+        result.stdout.fnmatch_lines([
+            "*hello*",
+            "*EXAMPLE LOCATION UNKNOWN, not showing all tests of that example*",
+            "*1/0*",
+            "*UNEXPECTED*ZeroDivision*",
+            "*1 failed*",
+        ])
+
+
     def test_doctest_unex_importerror(self, testdir):
         testdir.tmpdir.join("hello.py").write(py.code.Source("""
             import asdalsdkjaslkdjasd