Fix test schema inference.

Author: claudevdm

sdks/python/apache_beam/io/external/xlang_jdbcio_it_test.py

@@ -399,9 +399,9 @@ def test_xlang_jdbc_custom_statements(self, database):
               classpath=config['classpath'],
               statement=write_statement))
 
-    read_query = f"SELECT id, name, value FROM {table_name} WHERE value > \
-        25.0 ORDER BY id"
-
+    # Schema inference fails when there is a WHERE clause, so we pass explicit
+    # schema.
+    read_query = f"SELECT id, name, value FROM {table_name} WHERE value > 25.0"
     expected_filtered_rows = [row for row in test_rows if row.value > 25.0]
 
     with TestPipeline() as p:
@@ -415,23 +415,26 @@ def test_xlang_jdbc_custom_statements(self, database):
               username=config['username'],
               password=config['password'],
               classpath=config['classpath'],
-              query=read_query))
+              query=read_query,
+              schema=SimpleRow))
 
       assert_that(result, equal_to(expected_filtered_rows))
 
+    # JdbcIO#readWithPartitions requires custom queries to be passed as a
+    # wrapped subquery to table_name.
     with TestPipeline() as p:
       p.not_use_test_runner_api = True
       result = (
           p
           | 'Read with custom query' >> ReadFromJdbc(
-              table_name="",
+              table_name=f"{read_query} as subq",
               driver_class_name=config['driver_class_name'],
               jdbc_url=config['jdbc_url'],
               username=config['username'],
               password=config['password'],
               classpath=config['classpath'],
-              query=read_query,
-              partition_column="id"))
+              partition_column="id",
+              schema=SimpleRow))
 
       assert_that(result, equal_to(expected_filtered_rows))