test_rerere: Use an example that reorders to the same state

Change the example so that leftover_index becomes empty.

To make leftover_index empty, i.e. keep the final state unchanged
as a sum of both changes, it makes more conceptual sense
when one commit does not effectively revert the other.

That should also be more representative of real commits that can
sensibly be reordered.

Prework for #132

Author: anordal

tests/test_rerere.py

@@ -15,8 +15,8 @@ def history_with_two_conflicting_commits(auto_update: bool = False) -> None:
         git config rerere.enabled true
         git config rerere.autoUpdate {"true" if auto_update else "false"}
         echo > file; git add file; git commit -m 'initial commit'
-        echo one > file; git commit -am 'commit one'
-        echo two > file; git commit -am 'commit two'
+        echo eggs > file; git commit -am 'add eggs'
+        echo eggs spam > file; git commit -am 'add spam'
         """
     )
 
@@ -26,7 +26,7 @@ def history_with_two_conflicting_commits(auto_update: bool = False) -> None:
     [
         (True, None),
         (False, None),
-        (False, "custom resolution"),
+        (False, "only spam"),
     ],
 )
 def test_reuse_recorded_resolution(
@@ -40,16 +40,16 @@ def test_reuse_recorded_resolution(
     with editor_main(("-i", "HEAD~~"), input=b"y\n" * 4) as ed:
         flip_last_two_commits(repo, ed)
         with ed.next_file() as f:
-            f.replace_dedent("resolved two\n")
+            f.replace_dedent("spam\n")
         with ed.next_file() as f:
-            f.replace_dedent("resolved one\n")
+            f.replace_dedent("eggs spam\n")
 
     tree_after_resolving_conflicts = repo.get_commit("HEAD").tree()
     bash("git reset --hard HEAD@{1}")
 
     # Cached case: Test auto-using, accepting or declining the recorded resolution.
     acceptance_input = None
-    intermediate_state = "resolved two"
+    intermediate_state = "spam"
     if not auto_update:
         acceptance_input = b"y\n" * 2
         if custom_resolution is not None:
@@ -62,7 +62,7 @@ def test_reuse_recorded_resolution(
             with ed.next_file() as f:
                 f.replace_dedent(custom_resolution + "\n")
             with ed.next_file() as f:
-                f.replace_dedent("resolved one\n")
+                f.replace_dedent("eggs spam\n")
 
     assert tree_after_resolving_conflicts == repo.get_commit("HEAD").tree()
 
@@ -76,15 +76,9 @@ def test_reuse_recorded_resolution(
         f"""\
             @@ -1 +1 @@
             -{intermediate_state}
-            +resolved one"""
-    )
-    leftover_index = hunks(repo.git("diff", "-U0", "HEAD"))
-    assert leftover_index == dedent(
-        """\
-        @@ -1 +1 @@
-        -resolved one
-        +two"""
+            +eggs spam"""
     )
+    assert uncommitted_changes(repo) == ""
 
 
 def test_rerere_merge(repo: Repository) -> None:
@@ -151,9 +145,11 @@ def test_replay_resolution_recorded_by_git(repo: Repository) -> None:
         two=$(git rev-parse HEAD)
         git reset --hard HEAD~~
         git cherry-pick "$two" 2>&1 | grep 'could not apply'
-        echo resolved two > file; git add file; GIT_EDITOR=: git cherry-pick --continue
+        echo intermediate state > file
+        git add file; GIT_EDITOR=: git cherry-pick --continue
         git cherry-pick "$one" 2>&1 | grep 'could not apply'
-        echo resolved one > file; git add file; GIT_EDITOR=: git cherry-pick --continue --no-edit
+        echo something completely different > file
+        git add file; GIT_EDITOR=: git cherry-pick --continue --no-edit
         git reset --hard "$two"
         """
     )
@@ -164,33 +160,33 @@ def test_replay_resolution_recorded_by_git(repo: Repository) -> None:
 
     assert repo.git("log", "-p", trim_newline=False).decode() == dedent(
         """\
-        commit dc50430ecbd2d0697ee9266ba6057e0e0b511d7f
+        commit 44fdce0cf7ae75ed5edac5f3defed83cddf3ec4a
         Author: Bash Author <[email protected]>
         Date:   Thu Jul 13 21:40:00 2017 -0500
 
-            commit one
+            add eggs
 
         diff --git a/file b/file
-        index 474b904..936bcfd 100644
+        index 5d0f8a8..cb90548 100644
         --- a/file
         +++ b/file
         @@ -1 +1 @@
-        -resolved two
-        +resolved one
+        -intermediate state
+        +something completely different
 
-        commit e51ab202e87f0557df78e5273dcedf51f408a468
+        commit 1fa5135a6cce1f63dc2f5584ee68e15a4de3a99c
         Author: Bash Author <[email protected]>
         Date:   Thu Jul 13 21:40:00 2017 -0500
 
-            commit two
+            add spam
 
         diff --git a/file b/file
-        index 8b13789..474b904 100644
+        index 8b13789..5d0f8a8 100644
         --- a/file
         +++ b/file
         @@ -1 +1 @@
         -
-        +resolved two
+        +intermediate state
 
         commit d72132e74176624d6c3e5b6b4f5ef774ff23a1b3
         Author: Bash Author <[email protected]>
@@ -356,3 +352,7 @@ def normalize_conflict_dedent(indented_conflict: str) -> Tuple[str, str]:
 
 def hunks(diff: bytes) -> str:
     return diff[diff.index(b"@@") :].decode()
+
+
+def uncommitted_changes(repo: Repository) -> str:
+    return repo.git("diff", "-U0", "HEAD").decode()