generate-working-copy-states: generalize for depth

The script can currently generate filenames and contents for exactly
two changesets plus the working copy. For some tests (e.g. of plain
dirstate status), only one changeset is needed, while for others
(e.g. merge), three changesets are needed. Let's prepare for such
tests by generalizing the code for any number of changesets.

tests/generate-working-copy-states.py

@@ -2,29 +2,34 b''
 import sys
 import os
 
-# build the combination of possible states
-combination = []
-for base in [None, 'content1']:
-    for parent in set([None, 'content2']) | set([base]):
-        for wcc in set([None, 'content3']) | set([base, parent]):
+# Generates pairs of (filename, contents), where 'contents' is a list
+# describing the file's content at each revision (or in the working copy).
+# At each revision, it is either None or the file's actual content. When not
+# None, it may be either new content or the same content as an earlier
+# revisions, so all of (modified,clean,added,removed) can be tested.
+def generatestates(maxchangesets, parentcontents):
+    depth = len(parentcontents)
+    if depth == maxchangesets + 1:
             for tracked in ('untracked', 'tracked'):
-                def statestring(content):
-                    return content is None and 'missing' or content
-                filename = "%s_%s_%s-%s" % (statestring(base),
-                                            statestring(parent),
-                                            statestring(wcc),
-                                            tracked)
-                combination.append((filename, base, parent, wcc))
+            filename = "_".join([(content is None and 'missing' or content) for
+                                 content in parentcontents]) + "-" + tracked
+            yield (filename, parentcontents)
+    else:
+        for content in (set([None, 'content' + str(depth + 1)]) |
+                      set(parentcontents)):
+            for combination in generatestates(maxchangesets,
+                                              parentcontents + [content]):
+                yield combination
 
-# make sure we have stable output
-combination.sort()
+# sort to make sure we have stable output
+combinations = sorted(generatestates(2, []))
 
 # retrieve the state we must generate
 target = sys.argv[1]
 
 # compute file content
 content = []
-for filename, base, parent, wcc in combination:
+for filename, [base, parent, wcc] in combinations:
     if target == 'filelist':
         print filename
     elif target == 'base':