Edit all messages of consecutive squashed commits in one go

Closes #77

gitrevise/todo.py

@@ -1,6 +1,6 @@
 import re
 from enum import Enum
-from typing import List, Optional
+from typing import List, Optional, Tuple
 
 from .odb import Commit, Repository, MissingObject
 from .utils import run_editor, run_sequence_editor, edit_commit_message, cut_commit
@@ -240,19 +240,58 @@ def edit_todos(
     return result
 
 
+def is_fixup(todo: Step) -> bool:
+    return todo.kind in (StepKind.FIXUP, StepKind.SQUASH)
+
+
+def squash_message_template(
+    target_message: bytes, fixups: List[Tuple[StepKind, bytes]]
+) -> bytes:
+    fused = (
+        b"# This is a combination of %d commits.\n" % (len(fixups) + 1)
+        + b"# This is the 1st commit message:\n"
+        + b"\n"
+        + target_message
+    )
+
+    for i, (kind, message) in enumerate(fixups):
+        fused += b"\n"
+        if kind == StepKind.FIXUP:
+            fused += (
+                b"# The commit message #%d will be skipped:\n" % (i + 2)
+                + b"\n"
+                + b"".join(b"# " + line for line in message.splitlines(keepends=True))
+            )
+        else:
+            assert kind == StepKind.SQUASH
+            fused += b"# This is the commit message #%d:\n\n%s" % (i + 2, message)
+
+    return fused
+
+
 def apply_todos(current: Commit, todos: List[Step], reauthor: bool = False) -> Commit:
-    for step in todos:
+    fixups: List[Tuple[StepKind, bytes]] = []
+
+    for i, step in enumerate(todos):
         rebased = step.commit.rebase(current).update(message=step.message)
         if step.kind == StepKind.PICK:
             current = rebased
-        elif step.kind == StepKind.FIXUP:
+        elif is_fixup(step):
+            if not fixups:
+                fixup_target_message = current.message
+            fixups.append((step.kind, rebased.message))
             current = current.update(tree=rebased.tree())
+            is_last_fixup = i + 1 == len(todos) or not is_fixup(todos[i + 1])
+            if is_last_fixup and any(
+                kind == StepKind.SQUASH for kind, message in fixups
+            ):
+                current = current.update(
+                    message=squash_message_template(fixup_target_message, fixups)
+                )
+                current = edit_commit_message(current)
+                fixups.clear()
         elif step.kind == StepKind.REWORD:
             current = edit_commit_message(rebased)
-        elif step.kind == StepKind.SQUASH:
-            fused = current.message + b"\n\n" + rebased.message
-            current = current.update(tree=rebased.tree(), message=fused)
-            current = edit_commit_message(current)
         elif step.kind == StepKind.CUT:
             current = cut_commit(rebased)
         elif step.kind == StepKind.INDEX:

tests/test_fixup.py

@@ -375,3 +375,90 @@ def test_autosquash_multiline_summary(repo):
     new = repo.get_commit("HEAD")
     assert old != new, "commit was modified"
     assert old.parents() == new.parents(), "parents are unchanged"
+
+
+def test_autosquash_multiple_squashes(repo):
+    bash(
+        """
+        git commit --allow-empty -m 'initial commit'
+        git commit --allow-empty -m 'target'
+        git commit --allow-empty --squash :/^target --no-edit
+        git commit --allow-empty --squash :/^target --no-edit
+        """
+    )
+
+    with editor_main([":/^init", "--autosquash"], input=b"") as ed:
+        with ed.next_file() as f:
+            assert f.startswith_dedent(
+                """\
+                # This is a combination of 3 commits.
+                # This is the 1st commit message:
+
+                target
+
+                # This is the commit message #2:
+
+                squash! target
+
+                # This is the commit message #3:
+
+                squash! target
+                """
+            )
+            f.replace_dedent("two squashes")
+
+
+def test_autosquash_multiple_squashes_with_fixup(repo):
+    bash(
+        """
+        git commit --allow-empty -m 'initial commit'
+        git commit --allow-empty -m 'target'
+        git commit --allow-empty --squash :/^target --no-edit
+        git commit --allow-empty --fixup :/^target --no-edit
+        git commit --allow-empty --squash :/^target --no-edit
+        git commit --allow-empty -m 'unrelated'
+        """
+    )
+    with editor_main([":/^init", "--autosquash"], input=b"") as ed:
+        with ed.next_file() as f:
+            assert f.startswith_dedent(
+                """\
+                # This is a combination of 4 commits.
+                # This is the 1st commit message:
+
+                target
+
+                # This is the commit message #2:
+
+                squash! target
+
+                # The commit message #3 will be skipped:
+
+                # fixup! target
+
+                # This is the commit message #4:
+
+                squash! target
+                """
+            )
+            f.replace_dedent("squashes + fixup")
+
+
+def test_autosquash_multiple_independent_squashes(repo):
+    bash(
+        """
+        git commit --allow-empty -m 'initial commit'
+        git commit --allow-empty -m 'target1'
+        git commit --allow-empty -m 'target2'
+        git commit --allow-empty --squash :/^target1 --no-edit
+        git commit --allow-empty --squash :/^target2 --no-edit
+        """
+    )
+
+    with editor_main([":/^init", "--autosquash"], input=b"") as ed:
+        with ed.next_file() as f:
+            assert f.startswith_dedent("# This is a combination of 2 commits.")
+            f.replace_dedent("squash 1")
+        with ed.next_file() as f:
+            assert f.startswith_dedent("# This is a combination of 2 commits.")
+            f.replace_dedent("squash 2")