--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-absorb-filefixupstate.py	Mon Jul 30 14:05:56 2018 -0400
@@ -0,0 +1,207 @@
+from __future__ import absolute_import, print_function
+
+import itertools
+
+from hgext import absorb
+
+class simplefctx(object):
+    def __init__(self, content):
+        self.content = content
+
+    def data(self):
+        return self.content
+
+def insertreturns(x):
+    # insert "\n"s after each single char
+    if isinstance(x, str):
+        return ''.join(ch + '\n' for ch in x)
+    else:
+        return map(insertreturns, x)
+
+def removereturns(x):
+    # the revert of "insertreturns"
+    if isinstance(x, str):
+        return x.replace('\n', '')
+    else:
+        return map(removereturns, x)
+
+def assertlistequal(lhs, rhs, decorator=lambda x: x):
+    if lhs != rhs:
+        raise RuntimeError('mismatch:\n actual:   %r\n expected: %r'
+                           % tuple(map(decorator, [lhs, rhs])))
+
+def testfilefixup(oldcontents, workingcopy, expectedcontents, fixups=None):
+    """([str], str, [str], [(rev, a1, a2, b1, b2)]?) -> None
+
+    workingcopy is a string, of which every character denotes a single line.
+
+    oldcontents, expectedcontents are lists of strings, every character of
+    every string denots a single line.
+
+    if fixups is not None, it's the expected fixups list and will be checked.
+    """
+    expectedcontents = insertreturns(expectedcontents)
+    oldcontents = insertreturns(oldcontents)
+    workingcopy = insertreturns(workingcopy)
+    state = absorb.filefixupstate(map(simplefctx, oldcontents))
+    state.diffwith(simplefctx(workingcopy))
+    if fixups is not None:
+        assertlistequal(state.fixups, fixups)
+    state.apply()
+    assertlistequal(state.finalcontents, expectedcontents, removereturns)
+
+def buildcontents(linesrevs):
+    # linesrevs: [(linecontent : str, revs : [int])]
+    revs = set(itertools.chain(*[revs for line, revs in linesrevs]))
+    return [''] + [
+        ''.join([l for l, rs in linesrevs if r in rs])
+        for r in sorted(revs)
+    ]
+
+# input case 0: one single commit
+case0 = ['', '11']
+
+# replace a single chunk
+testfilefixup(case0, '', ['', ''])
+testfilefixup(case0, '2', ['', '2'])
+testfilefixup(case0, '22', ['', '22'])
+testfilefixup(case0, '222', ['', '222'])
+
+# input case 1: 3 lines, each commit adds one line
+case1 = buildcontents([
+    ('1', [1, 2, 3]),
+    ('2', [   2, 3]),
+    ('3', [      3]),
+])
+
+# 1:1 line mapping
+testfilefixup(case1, '123', case1)
+testfilefixup(case1, '12c', ['', '1', '12', '12c'])
+testfilefixup(case1, '1b3', ['', '1', '1b', '1b3'])
+testfilefixup(case1, '1bc', ['', '1', '1b', '1bc'])
+testfilefixup(case1, 'a23', ['', 'a', 'a2', 'a23'])
+testfilefixup(case1, 'a2c', ['', 'a', 'a2', 'a2c'])
+testfilefixup(case1, 'ab3', ['', 'a', 'ab', 'ab3'])
+testfilefixup(case1, 'abc', ['', 'a', 'ab', 'abc'])
+
+# non 1:1 edits
+testfilefixup(case1, 'abcd', case1)
+testfilefixup(case1, 'ab', case1)
+
+# deletion
+testfilefixup(case1, '',   ['', '', '', ''])
+testfilefixup(case1, '1',  ['', '1', '1', '1'])
+testfilefixup(case1, '2',  ['', '', '2', '2'])
+testfilefixup(case1, '3',  ['', '', '', '3'])
+testfilefixup(case1, '13', ['', '1', '1', '13'])
+
+# replaces
+testfilefixup(case1, '1bb3', ['', '1', '1bb', '1bb3'])
+
+# (confusing) replaces
+testfilefixup(case1, '1bbb', case1)
+testfilefixup(case1, 'bbbb', case1)
+testfilefixup(case1, 'bbb3', case1)
+testfilefixup(case1, '1b', case1)
+testfilefixup(case1, 'bb', case1)
+testfilefixup(case1, 'b3', case1)
+
+# insertions at the beginning and the end
+testfilefixup(case1, '123c', ['', '1', '12', '123c'])
+testfilefixup(case1, 'a123', ['', 'a1', 'a12', 'a123'])
+
+# (confusing) insertions
+testfilefixup(case1, '1a23', case1)
+testfilefixup(case1, '12b3', case1)
+
+# input case 2: delete in the middle
+case2 = buildcontents([
+    ('11', [1, 2]),
+    ('22', [1   ]),
+    ('33', [1, 2]),
+])
+
+# deletion (optimize code should make it 2 chunks)
+testfilefixup(case2, '', ['', '22', ''],
+              fixups=[(4, 0, 2, 0, 0), (4, 2, 4, 0, 0)])
+
+# 1:1 line mapping
+testfilefixup(case2, 'aaaa', ['', 'aa22aa', 'aaaa'])
+
+# non 1:1 edits
+# note: unlike case0, the chunk is not "continuous" and no edit allowed
+testfilefixup(case2, 'aaa', case2)
+
+# input case 3: rev 3 reverts rev 2
+case3 = buildcontents([
+    ('1', [1, 2, 3]),
+    ('2', [   2   ]),
+    ('3', [1, 2, 3]),
+])
+
+# 1:1 line mapping
+testfilefixup(case3, '13', case3)
+testfilefixup(case3, '1b', ['', '1b', '12b', '1b'])
+testfilefixup(case3, 'a3', ['', 'a3', 'a23', 'a3'])
+testfilefixup(case3, 'ab', ['', 'ab', 'a2b', 'ab'])
+
+# non 1:1 edits
+testfilefixup(case3, 'a', case3)
+testfilefixup(case3, 'abc', case3)
+
+# deletion
+testfilefixup(case3, '', ['', '', '2', ''])
+
+# insertion
+testfilefixup(case3, 'a13c', ['', 'a13c', 'a123c', 'a13c'])
+
+# input case 4: a slightly complex case
+case4 = buildcontents([
+    ('1', [1, 2, 3]),
+    ('2', [   2, 3]),
+    ('3', [1, 2,  ]),
+    ('4', [1,    3]),
+    ('5', [      3]),
+    ('6', [   2, 3]),
+    ('7', [   2   ]),
+    ('8', [   2, 3]),
+    ('9', [      3]),
+])
+
+testfilefixup(case4, '1245689', case4)
+testfilefixup(case4, '1a2456bbb', case4)
+testfilefixup(case4, '1abc5689', case4)
+testfilefixup(case4, '1ab5689', ['', '134', '1a3678', '1ab5689'])
+testfilefixup(case4, 'aa2bcd8ee', ['', 'aa34', 'aa23d78', 'aa2bcd8ee'])
+testfilefixup(case4, 'aa2bcdd8ee',['', 'aa34', 'aa23678', 'aa24568ee'])
+testfilefixup(case4, 'aaaaaa', case4)
+testfilefixup(case4, 'aa258b', ['', 'aa34', 'aa2378', 'aa258b'])
+testfilefixup(case4, '25bb', ['', '34', '23678', '25689'])
+testfilefixup(case4, '27', ['', '34', '23678', '245689'])
+testfilefixup(case4, '28', ['', '34', '2378', '28'])
+testfilefixup(case4, '', ['', '34', '37', ''])
+
+# input case 5: replace a small chunk which is near a deleted line
+case5 = buildcontents([
+    ('12', [1, 2]),
+    ('3',  [1]),
+    ('4',  [1, 2]),
+])
+
+testfilefixup(case5, '1cd4', ['', '1cd34', '1cd4'])
+
+# input case 6: base "changeset" is immutable
+case6 = ['1357', '0125678']
+
+testfilefixup(case6, '0125678', case6)
+testfilefixup(case6, '0a25678', case6)
+testfilefixup(case6, '0a256b8', case6)
+testfilefixup(case6, 'abcdefg', ['1357', 'a1c5e7g'])
+testfilefixup(case6, 'abcdef', case6)
+testfilefixup(case6, '', ['1357', '157'])
+testfilefixup(case6, '0123456789', ['1357', '0123456789'])
+
+# input case 7: change an empty file
+case7 = ['']
+
+testfilefixup(case7, '1', case7)