1 files changed, 39 insertions, 0 deletions
diff --git a/tests/test_using_api.py b/tests/test_using_api.py
new file mode 100644
index 0000000..7b0b030
--- /dev/null
+++ b/tests/test_using_api.py
@@ -0,0 +1,39 @@
+"""
+    Pygments tests for using()
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    :copyright: Copyright 2006-2022 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from pytest import raises
+
+from pygments.lexer import using, bygroups, this, RegexLexer
+from pygments.token import String, Text, Keyword
+
+
+class MyLexer(RegexLexer):
+    tokens = {
+        'root': [
+            (r'#.*',
+             using(this, state='invalid')),
+            (r'(")(.+?)(")',
+             bygroups(String, using(this, state='string'), String)),
+            (r'[^"]+', Text),
+        ],
+        'string': [
+            (r'.+', Keyword),
+        ],
+    }
+
+
+def test_basic():
+    expected = [(Text, 'a'), (String, '"'), (Keyword, 'bcd'),
+                (String, '"'), (Text, 'e\n')]
+    assert list(MyLexer().get_tokens('a"bcd"e')) == expected
+
+
+def test_error():
+    def gen():
+        return list(MyLexer().get_tokens('#a'))
+    assert raises(KeyError, gen)