API BREAK: Diff a/b logic fix for insert & delete

Fixed a ksconf.conf.delta glitch where a/b were backwards for DIFF_OP_INSERT
and DIFF_OP_DELETE.  This correction could impact any 3rd party code that
relies on the old behavior.  All built-in commands have been updated.

I'm confident this fixes #50.  Most likely this root issue of diff weirdness
and so it likely fixes #18.  Keep an eye open for regressions.

docs/source/changelog.rst

@@ -24,6 +24,12 @@ Release v0.7.3 (DRAFT)
 -   Improved some resource allocation in corner cases.
 
 
+..  attention:: **API BREAKAGE**
+
+    The ``DiffOp`` output values for ``DIFF_OP_INSERT`` and ``DIFF_OP_DELETE`` have been changed in a backwards-compatible breaking way.
+    The values of ``a`` and ``b`` were previously reversed for these two operations, leading to some code confusion.
+
+
 Release v0.7.2 (2019-03-22)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

ksconf/commands/promote.py

@@ -340,13 +340,13 @@ def prompt_yes_no(prompt):
                     # Move entire stanza
                     show_diff(self.stdout, [op])
                     if prompt_yes_no("Apply [{0}]".format(op.location.stanza)):
-                        out_cfg[op.location.stanza] = op.a
+                        out_cfg[op.location.stanza] = op.b
                         del out_src[op.location.stanza]
                 else:
                     show_diff(self.stdout, [op])
                     if prompt_yes_no("Apply [{0}] {1}".format(op.location.stanza, op.location.key)):
                         # Move key
-                        out_cfg[op.location.stanza][op.location.key] = op.a
+                        out_cfg[op.location.stanza][op.location.key] = op.b
                         del out_src[op.location.stanza][op.location.key]
                         # If last remaining key in the src stanza?  Then delete the entire stanza
                         if not out_src[op.location.stanza]:

ksconf/conf/delta.py

@@ -54,10 +54,10 @@ def compare_stanzas(a, b, stanza_name):
         return [DiffOp(DIFF_OP_EQUAL, DiffStanza("stanza", stanza_name), a, b) ]
     elif not b:
         # A only
-        return [ DiffOp(DIFF_OP_DELETE, DiffStanza("stanza", stanza_name), None, a) ]
+        return [ DiffOp(DIFF_OP_DELETE, DiffStanza("stanza", stanza_name), a, None) ]
     elif not a:
         # B only
-        return [ DiffOp(DIFF_OP_INSERT, DiffStanza("stanza", stanza_name), b, None) ]
+        return [ DiffOp(DIFF_OP_INSERT, DiffStanza("stanza", stanza_name), None, b) ]
     else:
         return list(_compare_stanzas(a, b, stanza_name))
 
@@ -72,9 +72,9 @@ def _compare_stanzas(a, b, stanza_name):
 
     # Level 2 - Key comparisons
     for key in kv_a:
-        yield DiffOp(DIFF_OP_DELETE, DiffStzKey("key", stanza_name, key), None, a[key])
+        yield DiffOp(DIFF_OP_DELETE, DiffStzKey("key", stanza_name, key), a[key], None)
     for key in kv_b:
-        yield DiffOp(DIFF_OP_INSERT, DiffStzKey("key", stanza_name, key), b[key], None)
+        yield DiffOp(DIFF_OP_INSERT, DiffStzKey("key", stanza_name, key), None, b[key])
     for key in kv_common:
         a_ = a[key]
         b_ = b[key]
@@ -155,10 +155,10 @@ def compare_cfgs(a, b, allow_level0=True):
                 delta.extend(_compare_stanzas(a[stanza], b[stanza], stanza))
         elif stanza in a:
             # A only
-            delta.append(DiffOp(DIFF_OP_DELETE, DiffStanza("stanza", stanza), None, a[stanza]))
+            delta.append(DiffOp(DIFF_OP_DELETE, DiffStanza("stanza", stanza), a[stanza], None))
         else:
             # B only
-            delta.append(DiffOp(DIFF_OP_INSERT, DiffStanza("stanza", stanza), b[stanza], None))
+            delta.append(DiffOp(DIFF_OP_INSERT, DiffStanza("stanza", stanza), None, b[stanza]))
     return delta
 
 
@@ -303,9 +303,9 @@ def f(v):
     for op in diffs:
         if isinstance(op.location, DiffStanza):
             if op.tag in (DIFF_OP_DELETE, DIFF_OP_REPLACE):
-                show_value(op.b, op.location.stanza, None, "-")
+                show_value(op.a, op.location.stanza, None, "-")
             if op.tag in (DIFF_OP_INSERT, DIFF_OP_REPLACE):
-                show_value(op.a, op.location.stanza, None, "+")
+                show_value(op.b, op.location.stanza, None, "+")
             continue  # pragma: no cover  (peephole optimization)
 
         if op.location.stanza != last_stanza:
@@ -318,9 +318,9 @@ def f(v):
             last_stanza = op.location.stanza
 
         if op.tag == DIFF_OP_INSERT:
-            show_value(op.a, op.location.stanza, op.location.key, "+")
+            show_value(op.b, op.location.stanza, op.location.key, "+")
         elif op.tag == DIFF_OP_DELETE:
-            show_value(op.b, op.location.stanza, op.location.key, "-")
+            show_value(op.a, op.location.stanza, op.location.key, "-")
         elif op.tag == DIFF_OP_REPLACE:
             if is_multiline(op.a) or is_multiline(op.b):
                 show_multiline_diff(op.a, op.b, op.location.key)

tests/test_parser.py

@@ -410,13 +410,14 @@ def test_compare_keys_props(self):
 
         op = self.find_op_by_location(diffs, "key", stanza="imapsync", key="DATETIME_CONFIG")
         self.assertEqual(op.tag, DIFF_OP_DELETE)
-        self.assertIsNone(op.a)
-        self.assertIsNotNone(op.b)
+        self.assertIsNotNone(op.a)
+        self.assertIsNone(op.b)
 
         op = self.find_op_by_location(diffs, "key", stanza="imapsync", key="description")
         self.assertEqual(op.tag, DIFF_OP_INSERT)
-        self.assertIsNotNone(op.a)
-        self.assertIsNone(op.b)
+        self.assertIsNone(op.a)
+        self.assertIsNotNone(op.b)
+
 
     def test_imballanced_stanas(self):
         """ Imbalanced stanzas """
@@ -487,11 +488,11 @@ def test_empty_stanzas(self):
 
         op = delta_search("stanza", stanza="in_b1")
         self.assertEqual(op.tag, DIFF_OP_INSERT)
-        self.assertEqual(op.a["live_in"], "b")
+        self.assertEqual(op.b["live_in"], "b")
 
         op = delta_search("stanza", stanza="in_a1")
         self.assertEqual(op.tag, DIFF_OP_DELETE)
-        self.assertEqual(op.b["live_in"], "a")
+        self.assertEqual(op.a["live_in"], "a")
 
     def test_summarize_compare_results(self):
         c1 = parse_string(self.cfg_props_imapsync_1)