diff --git a/src/documents/tests/search/test_stem_pattern_text.py b/src/documents/tests/search/test_stem_pattern_text.py
new file mode 100644
index 000000000..6dbb62c80
--- /dev/null
+++ b/src/documents/tests/search/test_stem_pattern_text.py
@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import pytest
+
+from documents.search._tokenizer import stem_pattern_text
+
+pytestmark = pytest.mark.search
+
+
+class TestStemPatternText:
+    def test_unsupported_language_returns_text_unchanged(self) -> None:
+        """
+        GIVEN:
+            - A language code with no Snowball stemmer mapping
+        WHEN:
+            - A pattern run is stemmed for that language
+        THEN:
+            - The run is returned unchanged, since the stemming gate that
+              disables stemming for an unsupported language also disables
+              the pattern-side stemmer
+        """
+        assert stem_pattern_text("running", "klingon") == "running"
+
+    def test_run_past_remove_long_limit_returns_text_unchanged(self) -> None:
+        """
+        GIVEN:
+            - A supported language and a run longer than the remove_long
+              filter's limit (129 characters, matching Document.title's
+              max_length)
+        WHEN:
+            - The over-long run is stemmed
+        THEN:
+            - The remove_long filter drops the token entirely, leaving no
+              stem to substitute, so the run is returned unchanged
+        """
+        long_run = "a" * 130
+        assert stem_pattern_text(long_run, "en") == long_run