diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index 6d19ece05d..05e43a31d3 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -9,6 +9,8 @@ Tests for template, signoff, squash and -F functions.'
 
 . ./test-lib.sh
 
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
 commit_msg_is () {
 	expect=commit_msg_is.expect
 	actual=commit_msg_is.actual
@@ -279,6 +281,163 @@ test_expect_success 'commit --fixup -m"something" -m"extra"' '
 
 extra"
 '
+get_commit_msg () {
+	rev="$1" &&
+	git log -1 --pretty=format:"%B" "$rev"
+}
+
+test_expect_success 'commit --fixup=amend: creates amend! commit' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=amend:HEAD~
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '--fixup=amend: --only ignores staged changes' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=amend:HEAD~ --only
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual &&
+	test_cmp_rev HEAD@{1}^{tree} HEAD^{tree} &&
+	test_cmp_rev HEAD@{1} HEAD^ &&
+	test_expect_code 1 git diff --cached --exit-code &&
+	git cat-file blob :foo >actual &&
+	test_cmp foo actual
+'
+
+test_expect_success '--fixup=reword: ignores staged changes' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited" \
+			git commit --fixup=reword:HEAD~
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual &&
+	test_cmp_rev HEAD@{1}^{tree} HEAD^{tree} &&
+	test_cmp_rev HEAD@{1} HEAD^ &&
+	test_expect_code 1 git diff --cached --exit-code &&
+	git cat-file blob :foo >actual &&
+	test_cmp foo actual
+'
+
+test_expect_success '--fixup=reword: error out with -m option' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine -m with --fixup:reword" >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -m "reword commit message" 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--fixup=amend: error out with -m option' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine -m with --fixup:amend" >expect &&
+	test_must_fail git commit --fixup=amend:HEAD~ -m "amend commit message" 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'consecutive amend! commits remove amend! line from commit msg body' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! amend! $(git log -1 --format=%s HEAD~)
+
+	$(get_commit_msg HEAD~)
+
+	edited 1
+
+	edited 2
+	EOF
+	echo "reword new commit message" >actual &&
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_AMEND="edited 1" \
+			git commit --fixup=reword:HEAD~ &&
+		FAKE_COMMIT_AMEND="edited 2" \
+			git commit --fixup=reword:HEAD
+	) &&
+	get_commit_msg HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'deny to create amend! commit if its commit msg body is empty' '
+	commit_for_rebase_autosquash_setup &&
+	echo "Aborting commit due to empty commit message body." >expected &&
+	(
+		set_fake_editor &&
+		test_must_fail env FAKE_COMMIT_MESSAGE="amend! target message subject line" \
+			git commit --fixup=amend:HEAD~ 2>actual
+	) &&
+	test_cmp expected actual
+'
+
+test_expect_success 'amend! commit allows empty commit msg body with --allow-empty-message' '
+	commit_for_rebase_autosquash_setup &&
+	cat >expected <<-EOF &&
+	amend! $(git log -1 --format=%s HEAD~)
+	EOF
+	(
+		set_fake_editor &&
+		FAKE_COMMIT_MESSAGE="amend! target message subject line" \
+			git commit --fixup=amend:HEAD~ --allow-empty-message &&
+		get_commit_msg HEAD >actual
+	) &&
+	test_cmp expected actual
+'
+
+test_fixup_reword_opt () {
+	test_expect_success C_LOCALE_OUTPUT "--fixup=reword: incompatible with $1" "
+		echo 'fatal: reword option of --fixup is mutually exclusive with'\
+			'--patch/--interactive/--all/--include/--only' >expect &&
+		test_must_fail git commit --fixup=reword:HEAD~ $1 2>actual &&
+		test_cmp expect actual
+	"
+}
+
+for opt in --all --include --only --interactive --patch
+do
+	test_fixup_reword_opt $opt
+done
+
+test_expect_success '--fixup=reword: give error with pathsec' '
+	commit_for_rebase_autosquash_setup &&
+	echo "fatal: cannot combine reword option of --fixup with path '\''foo'\''" >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -- foo 2>actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--fixup=reword: -F give error message' '
+	echo "fatal: Only one of -c/-C/-F/--fixup can be used." >expect &&
+	test_must_fail git commit --fixup=reword:HEAD~ -F msg  2>actual &&
+	test_cmp expect actual
+'
 
 test_expect_success 'commit --squash works with -F' '
 	commit_for_rebase_autosquash_setup &&