This patch adds the test for the commit
430d9f8f7ebb779948dbd43944b876b1a3f58551 ("Fix string.format("%c",
0)."). Although, the issue affects 2.0 branch only, there is no need to
fix it. Nevertheless, the test is required to avoid regressions in the
future.

Part of tarantool/tarantool#8069
---

PR: https://github.com/tarantool/tarantool/pull/8189
Branch: https://github.com/tarantool/luajit/tree/skaplun/lj-378-string-format-c-null-char-full-ci
Issues:
* https://github.com/tarantool/tarantool/issues/8069
* https://github.com/LuaJIT/LuaJIT/issues/378

 .../lj-378-string-format-c-null-char.test.lua | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 test/tarantool-tests/lj-378-string-format-c-null-char.test.lua

diff --git a/test/tarantool-tests/lj-378-string-format-c-null-char.test.lua b/test/tarantool-tests/lj-378-string-format-c-null-char.test.lua
new file mode 100644
index 00000000..15cefadf
--- /dev/null
+++ b/test/tarantool-tests/lj-378-string-format-c-null-char.test.lua
@@ -0,0 +1,11 @@
+local tap = require('tap')
+
+local test = tap.test('lj-378-string-format-c-null-char')
+test:plan(1)
+
+-- Test file to check that there is no regression in
+-- `string.format('%c', 0)` behaviour.
+-- See also https://github.com/LuaJIT/LuaJIT/issues/378.
+
+test:is(string.format('%c', 0), '\0', 'string.format %c on null char')
+os.exit(test:check() and 0 or 1)
--
2.34.1