tests: explore some bdiff cases

tests/test-bdiff.py

@@ -1,80 +1,94 b''
 from __future__ import absolute_import, print_function
 import struct
 from mercurial import (
     bdiff,
     mpatch,
 )
 
 def test1(a, b):
     d = bdiff.bdiff(a, b)
     c = a
     if d:
         c = mpatch.patches(a, [d])
     if c != b:
         print("bad diff+patch result from\n  %r to\n  %r:" % (a, b))
         print("bdiff: %r" % d)
         print("patched: %r" % c[:200])
 
 def test(a, b):
     print("test", repr(a), repr(b))
     test1(a, b)
     test1(b, a)
 
 test("a\nc\n\n\n\n", "a\nb\n\n\n")
 test("a\nb\nc\n", "a\nc\n")
 test("", "")
 test("a\nb\nc", "a\nb\nc")
 test("a\nb\nc\nd\n", "a\nd\n")
 test("a\nb\nc\nd\n", "a\nc\ne\n")
 test("a\nb\nc\n", "a\nc\n")
 test("a\n", "c\na\nb\n")
 test("a\n", "")
 test("a\n", "b\nc\n")
 test("a\n", "c\na\n")
 test("", "adjfkjdjksdhfksj")
 test("", "ab")
 test("", "abc")
 test("a", "a")
 test("ab", "ab")
 test("abc", "abc")
 test("a\n", "a\n")
 test("a\nb", "a\nb")
 
 #issue1295
 def showdiff(a, b):
     print('showdiff(\n  %r,\n  %r):' % (a, b))
     bin = bdiff.bdiff(a, b)
     pos = 0
     q = 0
     while pos < len(bin):
         p1, p2, l = struct.unpack(">lll", bin[pos:pos + 12])
         pos += 12
         if p1:
             print('', repr(a[q:p1]))
         print('', p1, p2, repr(a[p1:p2]), '->', repr(bin[pos:pos + l]))
         pos += l
         q = p2
     if q < len(a):
         print('', repr(a[q:]))
 
 showdiff("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\nx\n\nz\n")
 showdiff("x\n\nx\n\nx\n\nx\n\nz\n", "x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n")
 # we should pick up abbbc. rather than bc.de as the longest match
 showdiff("a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n",
          "a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n")
 
 print("done")
 
 def testfixws(a, b, allws):
     c = bdiff.fixws(a, allws)
     if c != b:
         print("*** fixws", repr(a), repr(b), allws)
         print("got:")
         print(repr(c))
 
 testfixws(" \ta\r b\t\n", "ab\n", 1)
 testfixws(" \ta\r b\t\n", " a b\n", 0)
 testfixws("", "", 1)
 testfixws("", "", 0)
 
 print("done")
+
+print("Odd diff for a trivial change:")
+showdiff(
+    ''.join('<%s\n-\n' % i for i in range(5)),
+    ''.join('>%s\n-\n' % i for i in range(5)))
+
+print("Diff 1 to 3 lines - preference for adding / removing at the end of sequences:")
+showdiff('a\n', 'a\n' * 3)
+print("Diff 1 to 5 lines - preference for adding / removing at the end of sequences:")
+showdiff('a\n', 'a\n' * 5)
+print("Diff 3 to 1 lines - preference for adding / removing at the end of sequences:")
+showdiff('a\n' * 3, 'a\n')
+print("Diff 5 to 1 lines - this diff seems weird:")
+showdiff('a\n' * 5, 'a\n')

tests/test-bdiff.py.out

@@ -1,44 +1,82 b''
 test 'a\nc\n\n\n\n' 'a\nb\n\n\n'
 test 'a\nb\nc\n' 'a\nc\n'
 test '' ''
 test 'a\nb\nc' 'a\nb\nc'
 test 'a\nb\nc\nd\n' 'a\nd\n'
 test 'a\nb\nc\nd\n' 'a\nc\ne\n'
 test 'a\nb\nc\n' 'a\nc\n'
 test 'a\n' 'c\na\nb\n'
 test 'a\n' ''
 test 'a\n' 'b\nc\n'
 test 'a\n' 'c\na\n'
 test '' 'adjfkjdjksdhfksj'
 test '' 'ab'
 test '' 'abc'
 test 'a' 'a'
 test 'ab' 'ab'
 test 'abc' 'abc'
 test 'a\n' 'a\n'
 test 'a\nb' 'a\nb'
 showdiff(
   'x\n\nx\n\nx\n\nx\n\nz\n',
   'x\n\nx\n\ny\n\nx\n\nx\n\nz\n'):
  'x\n\nx\n\n'
  6 6 '' -> 'y\n\n'
  'x\n\nx\n\nz\n'
 showdiff(
   'x\n\nx\n\nx\n\nx\n\nz\n',
   'x\n\nx\n\ny\n\nx\n\ny\n\nx\n\nz\n'):
  'x\n\nx\n\n'
  6 6 '' -> 'y\n\n'
  'x\n\n'
  9 9 '' -> 'y\n\n'
  'x\n\nz\n'
 showdiff(
   'a\nb\nb\nb\nc\n.\nd\ne\n.\nf\n',
   'a\nb\nb\na\nb\nb\nb\nc\n.\nb\nc\n.\nd\ne\nf\n'):
  0 0 '' -> 'a\nb\nb\n'
  'a\nb\nb\nb\nc\n.\n'
  12 12 '' -> 'b\nc\n.\n'
  'd\ne\n'
  16 18 '.\n' -> ''
  'f\n'
 done
 done
+Odd diff for a trivial change:
+showdiff(
+  '<0\n-\n<1\n-\n<2\n-\n<3\n-\n<4\n-\n',
+  '>0\n-\n>1\n-\n>2\n-\n>3\n-\n>4\n-\n'):
+ 0 8 '<0\n-\n<1\n' -> '>0\n'
+ '-\n'
+ 10 13 '<2\n' -> '>1\n'
+ '-\n'
+ 15 18 '<3\n' -> '>2\n'
+ '-\n'
+ 20 23 '<4\n' -> '>3\n'
+ '-\n'
+ 25 25 '' -> '>4\n-\n'
+Diff 1 to 3 lines - preference for adding / removing at the end of sequences:
+showdiff(
+  'a\n',
+  'a\na\na\n'):
+ 'a\n'
+ 2 2 '' -> 'a\na\n'
+Diff 1 to 5 lines - preference for adding / removing at the end of sequences:
+showdiff(
+  'a\n',
+  'a\na\na\na\na\n'):
+ 'a\n'
+ 2 2 '' -> 'a\na\na\na\n'
+Diff 3 to 1 lines - preference for adding / removing at the end of sequences:
+showdiff(
+  'a\na\na\n',
+  'a\n'):
+ 'a\n'
+ 2 6 'a\na\n' -> ''
+Diff 5 to 1 lines - this diff seems weird:
+showdiff(
+  'a\na\na\na\na\n',
+  'a\n'):
+ 0 2 'a\n' -> ''
+ 'a\n'
+ 4 10 'a\na\na\n' -> ''