Merge "Make an attempt at having taskflow exceptions print causes better"

taskflow/exceptions.py

@@ -18,6 +18,7 @@ import os
 import sys
 import traceback
 
+from oslo_utils import reflection
 import six
 
 
@@ -76,35 +77,51 @@ class TaskFlowException(Exception):
     def cause(self):
         return self._cause
 
-    def pformat(self, indent=2, indent_text=" "):
+    def __str__(self):
+        return self.pformat()
+
+    def _get_message(self):
+        # We must *not* call into the __str__ method as that will reactivate
+        # the pformat method, which will end up badly (and doesn't look
+        # pretty at all); so be careful...
+        return self.args[0]
+
+    def pformat(self, indent=2, indent_text=" ", show_root_class=False):
         """Pretty formats a taskflow exception + any connected causes."""
         if indent < 0:
-            raise ValueError("indent must be greater than or equal to zero")
-        return os.linesep.join(self._pformat(self, [], 0,
-                                             indent=indent,
-                                             indent_text=indent_text))
-
-    @classmethod
-    def _pformat(cls, excp, lines, current_indent, indent=2, indent_text=" "):
-        line_prefix = indent_text * current_indent
-        for line in traceback.format_exception_only(type(excp), excp):
-            # We'll add our own newlines on at the end of formatting.
-            #
-            # NOTE(harlowja): the reason we don't search for os.linesep is
-            # that the traceback module seems to only use '\n' (for some
-            # reason).
-            if line.endswith("\n"):
-                line = line[0:-1]
-            lines.append(line_prefix + line)
-        try:
-            cause = excp.cause
-        except AttributeError:
-            pass
-        else:
-            if cause is not None:
-                cls._pformat(cause, lines, current_indent + indent,
-                             indent=indent, indent_text=indent_text)
-        return lines
+            raise ValueError("Provided 'indent' must be greater than"
+                             " or equal to zero instead of %s" % indent)
+        buf = six.StringIO()
+        if show_root_class:
+            buf.write(reflection.get_class_name(self, fully_qualified=False))
+            buf.write(": ")
+        buf.write(self._get_message())
+        active_indent = indent
+        next_up = self.cause
+        while next_up is not None:
+            buf.write(os.linesep)
+            if isinstance(next_up, TaskFlowException):
+                buf.write(indent_text * active_indent)
+                buf.write(reflection.get_class_name(next_up,
+                                                    fully_qualified=False))
+                buf.write(": ")
+                buf.write(next_up._get_message())
+            else:
+                lines = traceback.format_exception_only(type(next_up), next_up)
+                for i, line in enumerate(lines):
+                    buf.write(indent_text * active_indent)
+                    if line.endswith("\n"):
+                        # We'll add our own newlines on...
+                        line = line[0:-1]
+                    buf.write(line)
+                    if i + 1 != len(lines):
+                        buf.write(os.linesep)
+            active_indent += indent
+            try:
+                next_up = next_up.cause
+            except AttributeError:
+                next_up = None
+        return buf.getvalue()
 
 
 # Errors related to storage or operations on storage units.

taskflow/tests/unit/test_exceptions.py

@@ -56,6 +56,44 @@ class TestExceptions(test.TestCase):
         self.assertIsNotNone(capture.cause)
         self.assertIsInstance(capture.cause, IOError)
 
+    def test_pformat_str(self):
+        ex = None
+        try:
+            try:
+                try:
+                    raise IOError("Didn't work")
+                except IOError:
+                    exc.raise_with_cause(exc.TaskFlowException,
+                                         "It didn't go so well")
+            except exc.TaskFlowException:
+                exc.raise_with_cause(exc.TaskFlowException, "I Failed")
+        except exc.TaskFlowException as e:
+            ex = e
+
+        self.assertIsNotNone(ex)
+        self.assertIsInstance(ex, exc.TaskFlowException)
+        self.assertIsInstance(ex.cause, exc.TaskFlowException)
+        self.assertIsInstance(ex.cause.cause, IOError)
+
+        p_msg = ex.pformat()
+        p_str_msg = str(ex)
+        for msg in ["I Failed", "It didn't go so well", "Didn't work"]:
+            self.assertIn(msg, p_msg)
+            self.assertIn(msg, p_str_msg)
+
+    def test_pformat_root_class(self):
+        ex = exc.TaskFlowException("Broken")
+        self.assertIn("TaskFlowException",
+                      ex.pformat(show_root_class=True))
+        self.assertNotIn("TaskFlowException",
+                         ex.pformat(show_root_class=False))
+        self.assertIn("Broken",
+                      ex.pformat(show_root_class=True))
+
+    def test_invalid_pformat_indent(self):
+        ex = exc.TaskFlowException("Broken")
+        self.assertRaises(ValueError, ex.pformat, indent=-100)
+
     @testtools.skipIf(not six.PY3, 'py3.x is not available')
     def test_raise_with_cause(self):
         capture = None