Handle inspect.getsourcelines failures in FixtureLookupError

Fixes #553

--HG--
branch : getsourcelines-error-issue-553-pytest2.7

CHANGELOG

@@ -1,6 +1,11 @@
 2.7.1.dev (compared to 2.7.0)
 -----------------------------
 
+- fix issue553: properly handling inspect.getsourcelines failures in
+  FixtureLookupError which would lead to to an internal error,
+  obfuscating the original problem. Thanks talljosh for initial
+  diagnose/patch and Bruno Oliveira for final patch.
+
 - fix issue660: properly report scope-mismatch-access errors
   independently from ordering of fixture arguments.  Also
   avoid the pytest internal traceback which does not provide

_pytest/python.py

@@ -1537,7 +1537,12 @@ class FixtureLookupError(LookupError):
                                # it at the requesting side
         for function in stack:
             fspath, lineno = getfslineno(function)
+            try:
                 lines, _ = inspect.getsourcelines(function)
+            except IOError:
+                error_msg = "file %s, line %s: source code not available"
+                addline(error_msg % (fspath, lineno+1))
+            else:
                 addline("file %s, line %s" % (fspath, lineno+1))
                 for i, line in enumerate(lines):
                     line = line.rstrip()

testing/acceptance_test.py

@@ -353,6 +353,23 @@ class TestGeneralUsage:
             *unrecognized*
         """)
 
+    def test_getsourcelines_error_issue553(self, testdir):
+        p = testdir.makepyfile("""
+            def raise_error(obj):
+                raise IOError('source code not available')
+
+            import inspect
+            inspect.getsourcelines = raise_error
+
+            def test_foo(invalid_fixture):
+                pass
+        """)
+        res = testdir.runpytest(p)
+        res.stdout.fnmatch_lines([
+            "*source code not available*",
+            "*fixture 'invalid_fixture' not found",
+        ])
+
 
 class TestInvocationVariants:
     def test_earlyinit(self, testdir):