1 files changed, 65 insertions, 0 deletions
diff --git a/tests/test_regexlexer.py b/tests/test_regexlexer.py
new file mode 100644
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+++ b/tests/test_regexlexer.py
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+"""
+    Pygments regex lexer tests
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    :copyright: Copyright 2006-2022 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+import pytest
+
+from pygments.token import Text, Whitespace
+from pygments.lexer import RegexLexer, default
+
+
+@pytest.fixture(scope='module')
+def lexer():
+    yield MyLexer()
+
+
+class MyLexer(RegexLexer):
+    """Test tuple state transitions including #pop."""
+    tokens = {
+        'root': [
+            ('a', Text.Root, 'rag'),
+            ('e', Text.Root),
+            ('#', Text.Root, '#pop'),
+            ('@', Text.Root, ('#pop', '#pop')),
+            default(('beer', 'beer'))
+        ],
+        'beer': [
+            ('d', Text.Beer, ('#pop', '#pop')),
+        ],
+        'rag': [
+            ('b', Text.Rag, '#push'),
+            ('c', Text.Rag, ('#pop', 'beer')),
+        ],
+    }
+
+
+def test_tuple(lexer):
+    toks = list(lexer.get_tokens_unprocessed('abcde'))
+    assert toks == [
+        (0, Text.Root, 'a'), (1, Text.Rag, 'b'), (2, Text.Rag, 'c'),
+        (3, Text.Beer, 'd'), (4, Text.Root, 'e')]
+
+
+def test_multiline(lexer):
+    toks = list(lexer.get_tokens_unprocessed('a\ne'))
+    assert toks == [
+        (0, Text.Root, 'a'), (1, Whitespace, '\n'), (2, Text.Root, 'e')]
+
+
+def test_default(lexer):
+    toks = list(lexer.get_tokens_unprocessed('d'))
+    assert toks == [(0, Text.Beer, 'd')]
+
+
+def test_pop_empty_regular(lexer):
+    toks = list(lexer.get_tokens_unprocessed('#e'))
+    assert toks == [(0, Text.Root, '#'), (1, Text.Root, 'e')]
+
+
+def test_pop_empty_tuple(lexer):
+    toks = list(lexer.get_tokens_unprocessed('@e'))
+    assert toks == [(0, Text.Root, '@'), (1, Text.Root, 'e')]