t3406: rework rebase reflog tests

Refactor the tests in preparation for adding more tests in the next
few commits. The reworked tests use the same function for testing both
the "merge" and "apply" backends. The test coverage for the "apply"
backend now includes setting GIT_REFLOG_ACTION.

Note that rebasing the "conflicts" branch does not create any
conflicts yet. A commit to do that will be added in the next commit
and the diff ends up smaller if we have don't rename the branch when
it is added.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3406-rebase-message.sh

@@ -10,10 +10,15 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 test_expect_success 'setup' '
 	test_commit O fileO &&
 	test_commit X fileX &&
+	git branch fast-forward &&
 	test_commit A fileA &&
 	test_commit B fileB &&
 	test_commit Y fileY &&
 
+	git checkout -b conflicts O &&
+	test_commit P &&
+	test_commit Q &&
+
 	git checkout -b topic O &&
 	git cherry-pick A B &&
 	test_commit Z fileZ &&
@@ -79,54 +84,86 @@ test_expect_success 'error out early upon -C<n> or --whitespace=<bad>' '
 	test_i18ngrep "Invalid whitespace option" err
 '
 
-test_expect_success 'GIT_REFLOG_ACTION' '
+write_reflog_expect () {
-	git checkout start &&
+	if test $mode = --apply
-	test_commit reflog-onto &&
+	then
-	git checkout -b reflog-topic start &&
+		sed 's/.*(finish)/rebase finished/; s/ ([^)]*)//'
-	test_commit reflog-to-rebase &&
+	else
+		cat
+	fi >expect
+}
 
-	git rebase reflog-onto &&
+test_reflog () {
-	git log -g --format=%gs -3 >actual &&
+	mode=$1
-	cat >expect <<-\EOF &&
+	reflog_action="$2"
-	rebase (finish): returning to refs/heads/reflog-topic
+
-	rebase (pick): reflog-to-rebase
+	test_expect_success "rebase $mode reflog${reflog_action:+ GIT_REFLOG_ACTION=$reflog_action}" '
-	rebase (start): checkout reflog-onto
+	git checkout conflicts &&
+	test_when_finished "git reset --hard Q" &&
+
+	(
+		if test -n "$reflog_action"
+		then
+			GIT_REFLOG_ACTION="$reflog_action" &&
+			export GIT_REFLOG_ACTION
+		fi &&
+		git rebase $mode main
+	) &&
+
+	git log -g --format=%gs -4 >actual &&
+	write_reflog_expect <<-EOF &&
+	${reflog_action:-rebase} (finish): returning to refs/heads/conflicts
+	${reflog_action:-rebase} (pick): Q
+	${reflog_action:-rebase} (pick): P
+	${reflog_action:-rebase} (start): checkout main
 	EOF
 	test_cmp expect actual &&
 
-	git checkout -b reflog-prefix reflog-to-rebase &&
+	git log -g --format=%gs -1 conflicts >actual &&
-	GIT_REFLOG_ACTION=change-the-reflog git rebase reflog-onto &&
+	write_reflog_expect <<-EOF &&
-	git log -g --format=%gs -3 >actual &&
+	${reflog_action:-rebase} (finish): refs/heads/conflicts onto $(git rev-parse main)
-	cat >expect <<-\EOF &&
-	change-the-reflog (finish): returning to refs/heads/reflog-prefix
-	change-the-reflog (pick): reflog-to-rebase
-	change-the-reflog (start): checkout reflog-onto
-	EOF
-	test_cmp expect actual
-'
-
-test_expect_success 'rebase --apply reflog' '
-	git checkout -b reflog-apply start &&
-	old_head_reflog="$(git log -g --format=%gs -1 HEAD)" &&
-
-	git rebase --apply Y &&
-
-	git log -g --format=%gs -4 HEAD >actual &&
-	cat >expect <<-EOF &&
-	rebase finished: returning to refs/heads/reflog-apply
-	rebase: Z
-	rebase: checkout Y
-	$old_head_reflog
 	EOF
 	test_cmp expect actual &&
 
-	git log -g --format=%gs -2 reflog-apply >actual &&
+	# check there is only one new entry in the branch reflog
-	cat >expect <<-EOF &&
+	test_cmp_rev conflicts@{1} Q
-	rebase finished: refs/heads/reflog-apply onto $(git rev-parse Y)
+	'
-	branch: Created from start
+
+	test_expect_success "rebase $mode fast-forward reflog${reflog_action:+ GIT_REFLOG_ACTION=$reflog_action}" '
+	git checkout fast-forward &&
+	test_when_finished "git reset --hard X" &&
+
+	(
+		if test -n "$reflog_action"
+		then
+			GIT_REFLOG_ACTION="$reflog_action" &&
+			export GIT_REFLOG_ACTION
+		fi &&
+		git rebase $mode main
+	) &&
+
+	git log -g --format=%gs -2 >actual &&
+	write_reflog_expect <<-EOF &&
+	${reflog_action:-rebase} (finish): returning to refs/heads/fast-forward
+	${reflog_action:-rebase} (start): checkout main
 	EOF
-	test_cmp expect actual
+	test_cmp expect actual &&
-'
+
+	git log -g --format=%gs -1 fast-forward >actual &&
+	write_reflog_expect <<-EOF &&
+	${reflog_action:-rebase} (finish): refs/heads/fast-forward onto $(git rev-parse main)
+	EOF
+	test_cmp expect actual &&
+
+	# check there is only one new entry in the branch reflog
+	test_cmp_rev fast-forward@{1} X
+	'
+}
+
+test_reflog --merge
+test_reflog --merge my-reflog-action
+test_reflog --apply
+test_reflog --apply my-reflog-action
 
 test_expect_success 'rebase -i onto unrelated history' '
 	git init unrelated &&