From 8c3e7b2179e922d8eefa6fdcd12bd4c5e6c41d0c Mon Sep 17 00:00:00 2001
From: Peter Grayson <pete@jpgrayson.net>
Date: Mon, 25 Oct 2021 11:29:36 -0400
Subject: [PATCH] Disallow committing empty patches by default

`stg commit` now refuses to commit empty patches by default, but also
learns the --allow-empty flag, which mirrors `git commit --allow-empty`,
to override this behavior.

Addresses #158

Signed-off-by: Peter Grayson <pete@jpgrayson.net>
---
 stgit/commands/commit.py | 25 ++++++++++++++++++++++++-
 t/t1009-gpg.sh           |  2 +-
 t/t1303-commit.sh        | 22 +++++++++++++---------
 3 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/stgit/commands/commit.py b/stgit/commands/commit.py
index 5ed995e..eacd560 100644
--- a/stgit/commands/commit.py
+++ b/stgit/commands/commit.py
@@ -21,7 +21,12 @@ along with this program; if not, see http://www.gnu.org/licenses/.
 
 help = 'Permanently store the applied patches into the stack base'
 kind = 'stack'
-usage = ['', '[--] <patchnames>', '-n NUM', '--all']
+usage = [
+    '[options]',
+    '[options] [--] <patchnames>',
+    '[options] -n NUM',
+    '[options] --all',
+]
 description = """
 Merge one or more patches into the base of the current stack and
 remove them from the series while advancing the base. This is the
@@ -45,6 +50,11 @@ options = [
         short='Commit the specified number of patches',
     ),
     opt('-a', '--all', action='store_true', short='Commit all applied patches'),
+    opt(
+        '--allow-empty',
+        action='store_true',
+        short='Allow empty patches to be committed',
+    ),
 ]
 
 directory = DirectoryHasRepository()
@@ -76,6 +86,19 @@ def func(parser, options, args):
     if not patches:
         raise CmdException('No patches to commit')
 
+    if not options.allow_empty:
+        empty_patches = [
+            pn for pn in patches
+            if stack.patches[pn].data.tree == stack.patches[pn].data.parent.data.tree
+        ]
+        if empty_patches:
+            raise CmdException(
+                'Empty patch%s (override with --allow-empty): %s' % (
+                    '' if len(empty_patches) == 1 else 'es',
+                    ', ' .join(empty_patches)
+                )
+            )
+
     iw = stack.repository.default_iw
 
     def allow_conflicts(trans):
diff --git a/t/t1009-gpg.sh b/t/t1009-gpg.sh
index 1606bc8..cd83994 100755
--- a/t/t1009-gpg.sh
+++ b/t/t1009-gpg.sh
@@ -48,7 +48,7 @@ test_expect_success GPG \
 
 test_expect_success GPG \
     'Patch remains signed after stg commit' '
-    stg commit -n 1 &&
+    stg commit --allow-empty -n 1 &&
     stg pop -a &&
     git verify-commit HEAD
 '
diff --git a/t/t1303-commit.sh b/t/t1303-commit.sh
index cc3574f..a9637ea 100755
--- a/t/t1303-commit.sh
+++ b/t/t1303-commit.sh
@@ -3,27 +3,31 @@ test_description='Test stg commit'
 . ./test-lib.sh
 
 test_expect_success 'Initialize the StGit repository' '
-    stg init
-'
-
-test_expect_success 'Commit middle patch' '
+    stg init &&
     stg new -m p1 &&
     stg new -m p2 &&
     stg new -m p3 &&
     stg new -m p4 &&
-    stg pop &&
-    stg commit p2 &&
+    stg pop
+'
+
+test_expect_success 'Attempt to commit an empty patch' '
+    command_error stg commit p2 2>&1 | grep "Empty patch"
+'
+
+test_expect_success 'Commit middle patch' '
+    stg commit --allow-empty p2 &&
     test "$(echo $(stg series))" = "+ p1 > p3 - p4"
 '
 
 test_expect_success 'Commit first patch' '
-    stg commit &&
+    stg commit --allow-empty &&
     test "$(echo $(stg series))" = "> p3 - p4"
 '
 
 test_expect_success 'Commit all patches' '
     stg push &&
-    stg commit -a &&
+    stg commit -a --allow-empty &&
     test "$(echo $(stg series))" = ""
 '
 
@@ -33,7 +37,7 @@ test_expect_success 'Commit when top != head (should fail)' '
     stg new -m foo &&
     git reset --hard HEAD^ &&
     h=$(git rev-parse HEAD)
-    command_error stg commit &&
+    command_error stg commit --allow-empty &&
     test "$(git rev-parse HEAD)" = "$h" &&
     test "$(echo $(stg series))" = "> foo"
 '
-- 
2.11.4.GIT