test: add failing test for EXCLUDE constraint WHERE clause being dropped

The deparser drops the WHERE clause from EXCLUDE USING ... WHERE (...) constraints.
The parser correctly preserves where_clause in the AST, but the CONSTR_EXCLUSION
handler in the deparser never outputs it.

This causes partial exclusion constraints to lose their predicate during
parse -> deparse cycles, which silently changes the constraint semantics.

Author: pyramation

__fixtures__/generated/generated.json

@@ -21327,6 +21327,7 @@
   "misc/issues-15.sql": "select \"A\" from \"table_name\"",
   "misc/issues-16.sql": "select \"AA\" from \"table_name\"",
   "misc/issues-17.sql": "SELECT CAST(t.date AT TIME ZONE $$America/New_York$$ AS text)::date FROM tbl t",
+  "misc/issues-18.sql": "CREATE TABLE test_exclude_where (\n  id uuid PRIMARY KEY,\n  database_id uuid NOT NULL,\n  status text NOT NULL DEFAULT 'pending',\n  EXCLUDE USING btree (database_id WITH =)\n    WHERE (status = 'pending')\n)",
   "misc/inflection-1.sql": "CREATE SCHEMA inflection",
   "misc/inflection-2.sql": "GRANT USAGE ON SCHEMA inflection TO PUBLIC",
   "misc/inflection-3.sql": "ALTER DEFAULT PRIVILEGES IN SCHEMA inflection \n GRANT EXECUTE ON FUNCTIONS  TO PUBLIC",

__fixtures__/kitchen-sink/misc/issues.sql

@@ -74,4 +74,14 @@ select "A" from "table_name";
 select "AA" from "table_name";
 
 -- https://github.com/constructive-io/pgsql-parser/issues/217
-SELECT CAST(t.date AT TIME ZONE $$America/New_York$$ AS text)::date FROM tbl t;
+SELECT CAST(t.date AT TIME ZONE $$America/New_York$$ AS text)::date FROM tbl t;
+
+-- EXCLUDE constraint with WHERE clause (partial exclusion constraint)
+-- The deparser drops the WHERE clause from EXCLUDE USING ... WHERE (...)
+CREATE TABLE test_exclude_where (
+  id uuid PRIMARY KEY,
+  database_id uuid NOT NULL,
+  status text NOT NULL DEFAULT 'pending',
+  EXCLUDE USING btree (database_id WITH =)
+    WHERE (status = 'pending')
+);

packages/deparser/__tests__/kitchen-sink/misc-issues.test.ts

@@ -20,6 +20,7 @@ it('misc-issues', async () => {
   "misc/issues-14.sql",
   "misc/issues-15.sql",
   "misc/issues-16.sql",
-  "misc/issues-17.sql"
+  "misc/issues-17.sql",
+  "misc/issues-18.sql"
 ]);
 });