Explicitly error when length of a searched term is larger than max

* bdx/index.py (DatabaseField.make_query): Raise an error when term is
too long.
* tests/test_index.py (test_searching_long_name): New test.

Author: mkcms

bdx/index.py

@@ -98,6 +98,13 @@ def make_query(self, value: str, wildcard: bool = False) -> xapian.Query:
         """
         value = self.preprocess_value(value).decode()
         term = f"{self.prefix}{value}"
+        if len(term) > MAX_TERM_SIZE:
+            msg = (
+                f"Term for '{self.name}' field is too long, max size "
+                f"is {MAX_TERM_SIZE-len(self.prefix)}: '{value[:30]}'..."
+            )
+            raise ValueError(msg)
+
         if wildcard:
             return xapian.Query(
                 xapian.Query.OP_WILDCARD,

tests/test_index.py

@@ -12,6 +12,7 @@
     SymbolNameField,
     index_binary_directory,
 )
+from bdx.query_parser import QueryParser
 
 # isort: on
 
@@ -415,6 +416,11 @@ def test_searching_by_basename(fixture_path, readonly_index):
         assert sym.path != fixture_path / "subdir" / "bar.cpp.o"
 
 
+def test_searching_long_name(fixture_path, readonly_index):
+    with pytest.raises(QueryParser.Error, match="'name'.*too long"):
+        readonly_index.search("a" * 300)
+
+
 def test_searching_cxx(readonly_index):
     symbols = readonly_index.search("cxx func")
     by_name = {x.name: x for x in symbols}