diff --git a/runtime/syntax/testdir/input/vim_expr.vim b/runtime/syntax/testdir/input/vim_expr.vim
new file mode 100644
index 0000000..0547e9b
--- /dev/null
+++ b/runtime/syntax/testdir/input/vim_expr.vim
@@ -0,0 +1,14 @@
+" String
+
+echo 'It''s a string'
+echo 'tab: \t, new line: \n, backslash: \\'
+echo "tab: \t, new line: \n, backslash: \\"
+
+" String interpolation
+
+echo 'Don''t highlight interpolation: {{ {1 + 2} }}'
+echo "Don't highlight interpolation: {{ {1 + 2} }}"
+echo $'Highlight interpolation:\t{{ { string({'foo': 'bar'}) } }}'
+echo $'Highlight interpolation:\t{{ { $'nested: {{ {1 + 2} }}' } }}'
+echo $"Highlight interpolation:\t{{ { string({"foo": "bar"}) } }}"
+echo $"Highlight interpolation:\t{{ { $"nested: {{ {1 + 2} }}" } }}"