fix: document library language facet undercounts text documents (#1758)

tests/test_document_library_language_facet.py

@@ -0,0 +1,28 @@
+"""Library language facet must SUM NULL-language and "text" docs.
+
+documents_library built the facet with {lang or "text": cnt ...}, so a
+NULL-language row and an explicit "text" row both keyed "text" and one
+silently overwrote the other. The language FILTER treats NULL and "text"
+as a single bucket ((language == None) | (language == "text")), so the
+facet count must add them, otherwise clicking the facet returns more docs
+than the count promised.
+"""
+from routes.document_routes import _aggregate_language_facets
+
+
+def test_null_and_text_are_summed():
+    rows = [(None, 3), ("text", 2), ("python", 5)]
+    assert _aggregate_language_facets(rows) == {"text": 5, "python": 5}
+
+
+def test_only_null():
+    assert _aggregate_language_facets([(None, 4)]) == {"text": 4}
+
+
+def test_distinct_languages_preserved():
+    rows = [("python", 2), ("javascript", 7), ("text", 1)]
+    assert _aggregate_language_facets(rows) == {"python": 2, "javascript": 7, "text": 1}
+
+
+def test_empty():
+    assert _aggregate_language_facets([]) == {}