Merge pull request #378 from buildout/annotate_verbose

verbose mode and select sections for annotate command

.gitignore

 .installed.cfg
 bin/
 build/
+include/
 develop-eggs/
 eggs/
 parts/

CHANGES.rst

@@ -4,7 +4,9 @@ Change History
 2.9.3 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Add more verbosity to ``annotate`` results with ``-v``
+
+- Select one or more sections with arguments after ``buildout annotate``.
 
 
 2.9.2 (2017-03-06)

doc/reference.rst

@@ -117,6 +117,19 @@ where they came from. Try it!
 
 .. _bootstrap-command:
 
+
+.. code-block:: console
+
+   buildout -v annotate
+
+  Increase the verbosity of the output to display all steps that compute the final values used by buildout.
+
+.. code-block:: console
+
+   buildout annotate versions
+  
+  You can pass one or more section names as arguments to display annotation only for the given sections.
+
 bootstrap
 _________
 

src/zc/buildout/buildout.py

@@ -75,49 +75,172 @@ class MissingSection(zc.buildout.UserError, KeyError):
         return "The referenced section, %r, was not defined." % self.args[0]
 
 
-def _annotate_section(section, note):
+def _annotate_section(section, source):
     for key in section:
-        section[key] = (section[key], note)
+        section[key] = SectionKey(section[key], source)
     return section
 
+
+class SectionKey(object):
+    def __init__(self, value, source):
+        self.history = []
+        self.value = value
+        self.addToHistory("SET", value, source)
+
+    @property
+    def source(self):
+        return self.history[-1].source
+
+    def overrideValue(self, sectionkey):
+        self.value = sectionkey.value
+        if sectionkey.history[-1].operation not in ['ADD', 'REMOVE']:
+            self.addToHistory("OVERRIDE", sectionkey.value, sectionkey.source)
+
+    def setDirectory(self, value):
+        self.value = value
+        self.addToHistory("DIRECTORY", value, self.source)
+
+    def addToValue(self, added, source):
+        subvalues = self.value.split('\n') + added.split('\n')
+        self.value = "\n".join(subvalues)
+        self.addToHistory("ADD", added, source)
+
+    def removeFromValue(self, removed, source):
+        subvalues = [
+            v
+            for v in self.value.split('\n')
+            if v not in removed.split('\n')
+        ]
+        self.value = "\n".join(subvalues)
+        self.addToHistory("REMOVE", removed, source)
+
+    def addToHistory(self, operation, value, source):
+        item = HistoryItem(operation, value, source)
+        self.history.append(item)
+
+    def printAll(self, key, basedir, verbose):
+        self.printKeyAndValue(key)
+        if verbose:
+            self.printVerbose(basedir)
+        else:
+            self.printTerse(basedir)
+
+    def printKeyAndValue(self, key):
+        lines = self.value.splitlines()
+        if len(lines) <= 1:
+            args = [key, "="]
+            if self.value:
+                args.append(" ")
+                args.append(self.value)
+            print_(*args, sep='')
+        else:
+            print_(key, "= ", lines[0], sep='')
+            for line in lines[1:]:
+                print_(line)
+
+    def printVerbose(self, basedir):
+        print_()
+        for item in reversed(self.history):
+            item.printAll(basedir)
+        print_()
+
+    def printTerse(self, basedir):
+        toprint = []
+        history = copy.deepcopy(self.history)
+        while history:
+            next = history.pop()
+            if next.operation in ["ADD", "REMOVE"]:
+                next.printShort(toprint, basedir)
+            else:
+                next.printShort(toprint, basedir)
+                break
+
+        for line in reversed(toprint):
+            if line.strip():
+                print_(line)
+
+    def __repr__(self):
+        return "<SectionKey value=%s source=%s>" % (
+            " ".join(self.value.split('\n')), self.source)
+
+
+class HistoryItem(object):
+    def __init__(self, operation, value, source):
+        self.operation = operation
+        self.value = value
+        self.source = source
+
+    def printShort(self, toprint, basedir):
+        source = self.source_for_human(basedir)
+        if self.operation in ["OVERRIDE", "SET", "DIRECTORY"]:
+            toprint.append("    " + source)
+        elif self.operation == "ADD":
+            toprint.append("+=  " + source)
+        elif self.operation == "REMOVE":
+            toprint.append("-=  " + source)
+
+    def printOperation(self):
+        lines = self.value.splitlines()
+        if len(lines) <= 1:
+            print_("  ", self.operation, "VALUE =", self.value)
+        else:
+            print_("  ", self.operation, "VALUE =")
+            for line in lines:
+                print_("  ", "  ", line)
+
+    def printSource(self, basedir):
+        if self.source in (
+            'DEFAULT_VALUE', 'COMPUTED_VALUE', 'COMMAND_LINE_VALUE'
+        ):
+            prefix = "AS"
+        else:
+            prefix = "IN"
+        print_("  ", prefix, self.source_for_human(basedir))
+
+    def source_for_human(self, basedir):
+        if self.source.startswith(basedir):
+            return os.path.relpath(self.source, basedir)
+        else:
+            return self.source
+
+    def printAll(self, basedir):
+        self.printSource(basedir)
+        self.printOperation()
+
+    def __repr__(self):
+        return "<HistoryItem operation=%s value=%s source=%s>" % (
+            self.operation, " ".join(self.value.split('\n')), self.source)
+
+
 def _annotate(data, note):
     for key in data:
         data[key] = _annotate_section(data[key], note)
     return data
 
-def _print_annotate(data):
+
+def _print_annotate(data, verbose, chosen_sections, basedir):
     sections = list(data.keys())
     sections.sort()
     print_()
     print_("Annotated sections")
     print_("="*len("Annotated sections"))
     for section in sections:
-        print_()
-        print_('[%s]' % section)
-        keys = list(data[section].keys())
-        keys.sort()
-        for key in keys:
-            value, notes = data[section][key]
-            keyvalue = "%s= %s" % (key, value)
-            print_(keyvalue)
-            line = '   '
-            for note in notes.split():
-                if note == '[+]':
-                    line = '+= '
-                elif note == '[-]':
-                    line = '-= '
-                else:
-                    print_(line, note)
-                    line = '   '
-    print_()
+        if (not chosen_sections) or (section in chosen_sections):
+            print_()
+            print_('[%s]' % section)
+            keys = list(data[section].keys())
+            keys.sort()
+            for key in keys:
+                sectionkey = data[section][key]
+                sectionkey.printAll(key, basedir, verbose)
 
 
 def _unannotate_section(section):
     for key in section:
-        value, note = section[key]
-        section[key] = value
+        section[key] = section[key].value
     return section
 
+
 def _unannotate(data):
     for key in data:
         data[key] = _unannotate_section(data[key])
@@ -164,6 +287,7 @@ _buildout_default_options = _annotate_section({
     'use-dependency-links': 'true',
     }, 'DEFAULT_VALUE')
 
+
 class Buildout(DictMixin):
 
     def __init__(self, config_file, cloptions,
@@ -173,12 +297,13 @@ class Buildout(DictMixin):
         __doing__ = 'Initializing.'
 
         # default options
-        data = dict(buildout=_buildout_default_options.copy())
+        _buildout_default_options_copy = copy.deepcopy(
+            _buildout_default_options)
+        data = dict(buildout=_buildout_default_options_copy)
         self._buildout_dir = os.getcwd()
 
         if config_file and not _isurl(config_file):
             config_file = os.path.abspath(config_file)
-            base = os.path.dirname(config_file)
             if not os.path.exists(config_file):
                 if command == 'init':
                     self._init_config(config_file, args)
@@ -186,7 +311,8 @@ class Buildout(DictMixin):
                     # Sigh. This model of a buildout instance
                     # with methods is breaking down. :(
                     config_file = None
-                    data['buildout']['directory'] = ('.', 'COMPUTED_VALUE')
+                    data['buildout']['directory'] = SectionKey(
+                        '.', 'COMPUTED_VALUE')
                 else:
                     raise zc.buildout.UserError(
                         "Couldn't open %s" % config_file)
@@ -195,19 +321,16 @@ class Buildout(DictMixin):
                     "%r already exists." % config_file)
 
             if config_file:
-                data['buildout']['directory'] = (os.path.dirname(config_file),
-                    'COMPUTED_VALUE')
-        else:
-            base = None
-
+                data['buildout']['directory'] = SectionKey(
+                    os.path.dirname(config_file), 'COMPUTED_VALUE')
 
         cloptions = dict(
-            (section, dict((option, (value, 'COMMAND_LINE_VALUE'))
+            (section, dict((option, SectionKey(value, 'COMMAND_LINE_VALUE'))
                            for (_, option, value) in v))
             for (section, v) in itertools.groupby(sorted(cloptions),
                                                   lambda v: v[0])
             )
-        override = cloptions.get('buildout', {}).copy()
+        override = copy.deepcopy(cloptions.get('buildout', {}))
 
         # load user defaults, which override defaults
         if user_defaults:
@@ -218,32 +341,35 @@ class Buildout(DictMixin):
                     os.path.expanduser('~'), '.buildout')
             user_config = os.path.join(buildout_home, 'default.cfg')
             if os.path.exists(user_config):
+                data_buildout_copy = copy.deepcopy(data['buildout'])
                 _update(data, _open(os.path.dirname(user_config), user_config,
-                                    [], data['buildout'].copy(), override,
+                                    [], data_buildout_copy, override,
                                     set()))
 
         # load configuration files
         if config_file:
+            data_buildout_copy = copy.deepcopy(data['buildout'])
             _update(data, _open(os.path.dirname(config_file), config_file, [],
-                                data['buildout'].copy(), override, set()))
+                                data_buildout_copy, override, set()))
 
         # apply command-line options
         _update(data, cloptions)
 
         # Set up versions section, if necessary
         if 'versions' not in data['buildout']:
-            data['buildout']['versions'] = ('versions', 'DEFAULT_VALUE')
+            data['buildout']['versions'] = SectionKey(
+                'versions', 'DEFAULT_VALUE')
             if 'versions' not in data:
                 data['versions'] = {}
 
         # Default versions:
-        versions_section_name = data['buildout']['versions'][0]
+        versions_section_name = data['buildout']['versions'].value
         if versions_section_name:
             versions = data[versions_section_name]
         else:
             versions = {}
         versions.update(
-            dict((k, (v, 'DEFAULT_VALUE'))
+            dict((k, SectionKey(v, 'DEFAULT_VALUE'))
                  for (k, v) in (
                      # Prevent downgrading due to prefer-final:
                      ('zc.buildout',
@@ -262,7 +388,9 @@ class Buildout(DictMixin):
         # file location
         for name in ('download-cache', 'eggs-directory', 'extends-cache'):
             if name in data['buildout']:
-                origdir, src = data['buildout'][name]
+                sectionkey = data['buildout'][name]
+                origdir = sectionkey.value
+                src = sectionkey.source
                 if '${' in origdir:
                     continue
                 if not os.path.isabs(origdir):
@@ -270,7 +398,7 @@ class Buildout(DictMixin):
                                'COMPUTED_VALUE',
                                'COMMAND_LINE_VALUE'):
                         if 'directory' in data['buildout']:
-                            basedir = data['buildout']['directory'][0]
+                            basedir = data['buildout']['directory'].value
                         else:
                             basedir = self._buildout_dir
                     else:
@@ -285,7 +413,7 @@ class Buildout(DictMixin):
                     if not os.path.isabs(absdir):
                         absdir = os.path.join(basedir, absdir)
                     absdir = os.path.abspath(absdir)
-                    data['buildout'][name] = (absdir, src)
+                    sectionkey.setDirectory(absdir)
 
         self._annotated = copy.deepcopy(data)
         self._raw = _unannotate(data)
@@ -365,7 +493,7 @@ class Buildout(DictMixin):
             versions = self[versions_section_name]
         else:
             # remove annotations
-            versions = dict((k, v[0]) for (k, v) in versions.items())
+            versions = dict((k, v.value) for (k, v) in versions.items())
         options['versions'] # refetching section name just to avoid a warning
         self.versions = versions
         zc.buildout.easy_install.default_versions(versions)
@@ -1106,7 +1234,13 @@ class Buildout(DictMixin):
     runsetup = setup # backward compat.
 
     def annotate(self, args=None):
-        _print_annotate(self._annotated)
+        verbose = self['buildout'].get('verbosity', 0) != 0
+        section = None
+        if args is None:
+            sections = []
+        else:
+            sections = args
+        _print_annotate(self._annotated, verbose, sections, self._buildout_dir)
 
     def print_options(self, base_path=None):
         for section in sorted(self._data):
@@ -1279,7 +1413,7 @@ class Options(DictMixin):
                 result.update(self._do_extend_raw(iname, raw, doing))
 
             result = _annotate_section(result, "")
-            data = _annotate_section(data.copy(), "")
+            data = _annotate_section(copy.deepcopy(data), "")
             _update_section(result, data)
             result = _unannotate_section(result)
             result.pop('<', None)
@@ -1405,7 +1539,7 @@ class Options(DictMixin):
         return len(self.keys())
 
     def copy(self):
-        result = self._raw.copy()
+        result = copy.deepcopy(self._raw)
         result.update(self._cooked)
         result.update(self._data)
         return result
@@ -1573,7 +1707,8 @@ def _open(base, filename, seen, dl_options, override, downloaded):
     Recursively open other files based on buildout options found.
     """
     _update_section(dl_options, override)
-    _dl_options = _unannotate_section(dl_options.copy())
+    dl_options_copy = copy.deepcopy(dl_options)
+    _dl_options = _unannotate_section(dl_options_copy)
     newest = bool_option(_dl_options, 'newest', 'false')
     fallback = newest and not (filename in downloaded)
     download = zc.buildout.download.Download(
@@ -1702,31 +1837,37 @@ def _update_section(s1, s2):
     # in section 2 overriding those in section 1. If there are += or -=
     # operators in section 2, process these to add or substract items (delimited
     # by newlines) from the preexisting values.
-    s2 = s2.copy() # avoid mutating the second argument, which is unexpected
+    s2 = copy.deepcopy(s2) # avoid mutating the second argument, which is unexpected
     # Sort on key, then on the addition or substraction operator (+ comes first)
     for k, v in sorted(s2.items(), key=lambda x: (x[0].rstrip(' +'), x[0][-1])):
-        v2, note2 = v
         if k.endswith('+'):
             key = k.rstrip(' +')
+            implicit_value = SectionKey("", "IMPLICIT_VALUE")
             # Find v1 in s2 first; it may have been defined locally too.
-            v1, note1 = s2.get(key, s1.get(key, ("", "")))
-            newnote = ' [+] '.join((note1, note2)).strip()
-            s2[key] = "\n".join((v1).split('\n') +
-                v2.split('\n')), newnote
+            section_key = s2.get(key, s1.get(key, implicit_value))
+            section_key.addToValue(v.value, v.source)
+            s2[key] = section_key
             del s2[k]
         elif k.endswith('-'):
             key = k.rstrip(' -')
+            implicit_value = SectionKey("", "IMPLICIT_VALUE")
             # Find v1 in s2 first; it may have been set by a += operation first
-            v1, note1 = s2.get(key, s1.get(key, ("", "")))
-            newnote = ' [-] '.join((note1, note2)).strip()
-            s2[key] = ("\n".join(
-                [v for v in v1.split('\n')
-                   if v not in v2.split('\n')]), newnote)
+            section_key = s2.get(key, s1.get(key, implicit_value))
+            section_key.removeFromValue(v.value, v.source)
+            s2[key] = section_key
             del s2[k]
 
-    s1.update(s2)
+    _update_verbose(s1, s2)
     return s1
 
+def _update_verbose(s1, s2):
+    for key, v2 in s2.items():
+        if key in s1:
+            v1 = s1[key]
+            v1.overrideValue(v2)
+        else:
+            s1[key] = v2
+
 def _update(d1, d2):
     for section in d2:
         if section in d1:

src/zc/buildout/buildout.txt

@@ -809,7 +809,7 @@ the origin of the value (file name or ``COMPUTED_VALUE``, ``DEFAULT_VALUE``,
     bin-directory= bin
         DEFAULT_VALUE
     develop= recipes
-        /sample-buildout/buildout.cfg
+        buildout.cfg
     develop-eggs-directory= develop-eggs
         DEFAULT_VALUE
     directory= /sample-buildout
@@ -833,7 +833,7 @@ the origin of the value (file name or ``COMPUTED_VALUE``, ``DEFAULT_VALUE``,
     offline= false
         DEFAULT_VALUE
     parts= data-dir
-        /sample-buildout/buildout.cfg
+        buildout.cfg
     parts-directory= parts
         DEFAULT_VALUE
     prefer-final= true
@@ -853,9 +853,178 @@ the origin of the value (file name or ``COMPUTED_VALUE``, ``DEFAULT_VALUE``,
     <BLANKLINE>
     [data-dir]
     path= foo bins
-        /sample-buildout/buildout.cfg
+        buildout.cfg
     recipe= recipes:mkdir
-        /sample-buildout/buildout.cfg
+        buildout.cfg
+    <BLANKLINE>
+    [versions]
+    zc.buildout = >=1.99
+        DEFAULT_VALUE
+    zc.recipe.egg = >=1.99
+        DEFAULT_VALUE
+    <BLANKLINE>
+
+The ``annotate`` command is sensitive to the verbosity flag. 
+You get more information about the way values are computed::
+
+    >>> print_(system(buildout+ ' -v annotate'), end='')
+    ... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
+    <BLANKLINE>
+    Annotated sections
+    ==================
+    <BLANKLINE>
+    [buildout]
+    allow-hosts= *
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = *
+    <BLANKLINE>
+    allow-picked-versions= true
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = true
+    <BLANKLINE>
+    bin-directory= bin
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = bin
+    <BLANKLINE>
+    develop= recipes
+    <BLANKLINE>
+       IN buildout.cfg
+       SET VALUE = recipes
+    <BLANKLINE>
+    develop-eggs-directory= develop-eggs
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = develop-eggs
+    <BLANKLINE>
+    directory= /sample-buildout
+    <BLANKLINE>
+       AS COMPUTED_VALUE
+       SET VALUE = /sample-buildout
+    <BLANKLINE>
+    eggs-directory= /sample-buildout/eggs
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       DIRECTORY VALUE = /sample-buildout/eggs
+       AS DEFAULT_VALUE
+       SET VALUE = eggs
+    <BLANKLINE>
+    executable= ...
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = ...
+    <BLANKLINE>
+    find-links=
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE =
+    <BLANKLINE>
+    install-from-cache= false
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = false
+    <BLANKLINE>
+    installed= .installed.cfg
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = .installed.cfg
+    <BLANKLINE>
+    log-format=
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE =
+    <BLANKLINE>
+    log-level= INFO
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = INFO
+    <BLANKLINE>
+    newest= true
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = true
+    <BLANKLINE>
+    offline= false
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = false
+    <BLANKLINE>
+    parts= data-dir
+    <BLANKLINE>
+       IN buildout.cfg
+       SET VALUE = data-dir
+    <BLANKLINE>
+    parts-directory= parts
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = parts
+    <BLANKLINE>
+    prefer-final= true
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = true
+    <BLANKLINE>
+    python= buildout
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = buildout
+    <BLANKLINE>
+    show-picked-versions= false
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = false
+    <BLANKLINE>
+    socket-timeout=
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE =
+    <BLANKLINE>
+    update-versions-file=
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE =
+    <BLANKLINE>
+    use-dependency-links= true
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = true
+    <BLANKLINE>
+    verbosity= 10
+    <BLANKLINE>
+       AS COMMAND_LINE_VALUE
+       SET VALUE = 10
+    <BLANKLINE>
+    versions= versions
+    <BLANKLINE>
+       AS DEFAULT_VALUE
+       SET VALUE = versions
+    <BLANKLINE>
+    <BLANKLINE>
+    [data-dir]
+    path= foo bins
+    <BLANKLINE>
+       IN buildout.cfg
+       SET VALUE = foo bins
+    <BLANKLINE>
+    recipe= recipes:mkdir
+    <BLANKLINE>
+       IN buildout.cfg
+       SET VALUE = recipes:mkdir
+    <BLANKLINE>
+    <BLANKLINE>
+    [versions]
+    ...
+
+The output of the ``annotate`` command can be very long.
+You can restrict the output to some sections by passing section names as arguments::
+
+    >>> print_(system(buildout+ ' annotate versions'), end='')
+    ... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
+    <BLANKLINE>
+    Annotated sections
+    ==================
     <BLANKLINE>
     [versions]
     zc.buildout= >=1.99
@@ -1384,42 +1553,42 @@ operations::
     option= a1 a2
     a3 a4
     a5
-        /sample-buildout/base.cfg
-    +=  /sample-buildout/extension1.cfg
-    +=  /sample-buildout/extension2.cfg
+        base.cfg
+    +=  extension1.cfg
+    +=  extension2.cfg
     recipe=
-        /sample-buildout/base.cfg
+        base.cfg
     <BLANKLINE>
     [part2]
     option= b1 b2 b3 b4
-        /sample-buildout/base.cfg
-    -=  /sample-buildout/extension1.cfg
-    -=  /sample-buildout/extension2.cfg
+        base.cfg
+    -=  extension1.cfg
+    -=  extension2.cfg
     recipe=
-        /sample-buildout/base.cfg
+        base.cfg
     <BLANKLINE>
     [part3]
     option= c1 c2
     c3 c4 c5
-        /sample-buildout/base.cfg
-    +=  /sample-buildout/extension1.cfg
+        base.cfg
+    +=  extension1.cfg
     recipe=
-        /sample-buildout/base.cfg
+        base.cfg
     <BLANKLINE>
     [part4]
     option= d2
     d3
     d1
     d4
-        /sample-buildout/base.cfg
-    +=  /sample-buildout/extension1.cfg
-    -=  /sample-buildout/extension1.cfg
+        base.cfg
+    +=  extension1.cfg
+    -=  extension1.cfg
     recipe=
-        /sample-buildout/base.cfg
+        base.cfg
     <BLANKLINE>
     [part5]
     option= h1 h2
-        /sample-buildout/extension1.cfg
+        extension1.cfg
     [versions]
     zc.buildout= >=1.99
         DEFAULT_VALUE
@@ -1427,6 +1596,77 @@ operations::
         DEFAULT_VALUE
     <BLANKLINE>
 
+With more verbosity::
+
+    >>> print_(system(os.path.join('bin', 'buildout') + ' -v annotate'), end='')
+    ... # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
+    <BLANKLINE>
+    Annotated sections
+    ==================
+    ...
+    [part1]
+    option= a1 a2
+    a3 a4
+    a5
+    <BLANKLINE>
+       IN extension2.cfg
+       ADD VALUE = a5
+       IN extension1.cfg
+       ADD VALUE = a3 a4
+       IN base.cfg
+       SET VALUE = a1 a2
+    <BLANKLINE>
+    ...
+    [part2]
+    option= b1 b2 b3 b4
+    <BLANKLINE>
+       IN extension2.cfg
+       REMOVE VALUE = b1 b2 b3
+       IN extension1.cfg
+       REMOVE VALUE = b1 b2
+       IN base.cfg
+       SET VALUE = b1 b2 b3 b4
+    <BLANKLINE>
+    ...
+    [part3]
+    option=
+       c1 c2
+       c3 c4 c5
+    <BLANKLINE>
+       IN extension1.cfg
+       ADD VALUE = c3 c4 c5
+       IN base.cfg
+       SET VALUE = c1 c2
+    <BLANKLINE>
+    ...
+    [part4]
+    option=
+       d2
+       d3
+       d1
+       d4
+    <BLANKLINE>
+       IN extension1.cfg
+       REMOVE VALUE = d5
+       IN extension1.cfg
+       ADD VALUE =
+          d1
+          d4
+       IN base.cfg
+       SET VALUE =
+          d2
+          d3
+          d5
+    <BLANKLINE>
+    ...
+    [part5]
+    option= h1 h2
+    <BLANKLINE>
+       IN extension1.cfg
+       SET VALUE = h1 h2
+    <BLANKLINE>
+    ...
+
 Cleanup::
 
     >>> os.remove(os.path.join(sample_buildout, 'base.cfg'))

src/zc/buildout/tests.py

@@ -3539,7 +3539,7 @@ def test_suite():
                     (re.compile('setuptools'), 'setuptools'),
                     (re.compile('Got zc.recipe.egg \S+'), 'Got zc.recipe.egg'),
                     (re.compile(r'zc\.(buildout|recipe\.egg)\s*= >=\S+'),
-                     'zc.\1 = >=1.99'),
+                     'zc.\\1 = >=1.99'),
                     ])
                 ) + manuel.capture.Manuel(),
             'buildout.txt',